ch 22 22.1 The value of biodiversity arises from social, economic, and ecological considerations

The decline in the world's biodiversity is at a critical stage because human activities threaten populations of many species. However, by appreciating the importance of the world's species and understanding their ecolog

we can take the steps necessary to slow population declines and species extinctions, and to find ways to coexist.

The task of protecting a suitable habitat becomes more complicated when a population's habitat requirements change with the seasons or when it undertakes large-scale seasonal migrations. migratory populations use the entire area of the Serengeti ecosystem annually buffalo can never be fully restored to North American prairies because their seasonal migration routes are now blocked by miles of fencing and agricultural fields Bison survive in a few small reserves in the American West

Because migratory populations use the entire area of the Serengeti ecosystem over the course of a year, the preservation of only one section would not meet their needs. Huge populations of wildebeests, zebras, and gazelles migrate seasonally also known as buffalo) can never be fully restored to North American prairies because their seasonal migration routes are now blocked by miles of fencing and agricultural fields. Bison survive in a few small reserves in the American West—most notably in the Greater Yellowstone Ecosystem This Greater Yellowstone Ecosystem, an 80 , 000 -km 2 area that is centered on Yellowstone National Park in Wyoming, is one of the best-known examples of preserving a large collection of habitat and includes federal, state, and private lands from three states

pangea Laurasia 150 mya= both americas continene separation-spp similar but evolve differently w splitting? 6 distinct biogeography regions w dif organisms groups oceans extended from tropics to polar, currents distributed heat more evenly, w dif land masses temperate climates nearer poles, heat disrib more evenly before North America and Eurasia went to northern polar temp 2 mya gradual cooling little ice age, alternating period/cooling warming retreating ice sheets 18 K ya, much area glaciated started seeing tress

250 MYs, lauraisa and other land mass Laurasia 150 mya split into both americas, south America fit into Africa , looking at Sameri and Africa fault lines continene separation-spp similar by evolve differently 6 distinct biogeography regions w dif organisms groups 215 million years big climate change, arctic can see remnants of tropic spp oceans extended from tropics to polar, currents distributed heat more evenly, temperate climates nearer poles, why Europe warmer than us antarctic land collection bw South America adn Australia supporting temperate veg and lots of animal life as arctic drifted to south , North America and Eurasia went to northern polar temp , now cooler temp higher latitude 2 mya gradual cooling little ice age, alternating period/cooling warming retreating ice sheets over time, plant spp change spruce migrate back adn forth , 18 K ya, much area glaciated started seeing tress spp accu curve , curve plateau, no new spp eventually that you'll find , don't continue sampling if finding no new spp graph num spp observed relation to num indivs sampled

Some extinctions are natural; some are caused by humans. Over the past 500 million years, the world has experienced five mass extinction events. Mass extinction events: events in which at least 75% of the existing species go extinct within a 2-million-year period.

75% extinct in 2 mil period, detemrinatined by fossil record

However, some pesticides do kill nonpests, either directly, by being toxic, or indirectly, by altering food webs, , va very small amount of an insecticide, while not directly toxic to tadpoles, was toxic to zooplankton.The death of zooplankton set off a chain of events in the food web that prevented the tadpoles from obtaining enough food to metamorphose before the pond dried By indirect effect, the insecticide caused the death of approximately half of the tadpoles. pesticides do kill nonpests(harm), toxic to zooplankton->starved out tadpoles populations of many predatory birds declined drastically. traced to pollution of aquatic habitats by DDT, used to control crop pests and mosquito vectors of malaria after World War II. DDT=insecticide

A classic study on pesticides examined the role of the insecticide DDT on birds of prey. During the 1950s and 1960s in the United States, populations of many predatory birds, particularly the peregrine falcon (Falco peregrinus), bald eagle, osprey (Pandion haliaetus), and brown pelican (Pelecanus occidentalis), declined drastically. Several of these species disappeared from large areas and the peregrine falcon disappeared from the entire eastern United States. The causes of these population declines were traced to pollution of aquatic habitats by DDT, an insecticide that was widely used to control crop pests and mosquito vectors of malaria after World War II. This insecticide was favored both because it was effective at killing insect pests and because it persisted in the environment, allowing it to continue killing pest insects for a long time.

For instance, compare the bars in the stacked bar graphs versus the sections in the pie charts for birds and mammals. The bar graph shows that mammals have approximately half the number of species when compared to birds. However, similar numbers of species in each group are in the threatened category. In the pie charts, comparing the percentages of species in each conservation category is easier. The relative proportion of threatened species in the mammals is larger than that in the birds stacked bar graph that has absolute numbers on the 𝑦-axis allows for the comparison of values within a bar and between bars. In the pie charts, comparing the percentages of species in each conservation category is easier.

A stacked bar graph makes it easier to compare the total number of species in each conservation category within and among taxonomic groups. A stacked bar graph that has absolute numbers on the 𝑦-axis allows for the comparison of values within a bar and between bars. In contrast, a pie chart allows for the comparison of percentages or relative frequencies within and among charts.

Some of these introductions are intentional, such as when tropical plants are sold for houseplants in temperate parts of the world. pathogens that have moved between continents and have caused emerging infectious diseases. A important benefits, such as the common honeybee

Another cause of declines in biodiversity is the increasing number of species that are introduced from one region to another. accident, as we saw in Chapter 14 with the many pathogens that have moved between continents and have caused emerging infectious diseases. Although only about 5 percent of introduced species become established in a new region, those that do can have a variety of effects. important benefits, such as the common honeybee that was introduced to North America from Europe in the 1600s. Other introduced species, though, can have substantial negative effects on native species, like the brown tree snake introduced to the island of Guam,'

However, harvesting regulations must balance not only the good of the harvested population but also the human employment that the harvest supports For example, modern fishing techniques have made it much easier to harvest enormous numbers of fish and shellfish.\ ability to fish more efficiently and to cover larger areas->decline of many fish populations around

As a result, some regulations set harvest levels that do not stop populations from declining. For example, modern fishing techniques have made it much easier to harvest enormous numbers of fish and shellfish.\ The ability to fish more efficiently and to cover larger areas has caused a decline of many fish populations around the world.

Reducing the harvest of a declining species often increases its abundance, although some species can take a long time to recover.

Example: By the late 1800s, it was thought that humans had hunted northern elephant seals to extinction. Small populations were discovered in the 1890s and were given protection by the United States and Mexico. The number of seals quickly rose from just 100 individuals to more than 150,000 today, and they are distributed throughout much of their former range.

For instance, the northern elephant seal (Mirounga angustirostris) was hunted so much that by the late 1800s it was thought to be extinct (Figure 22.24). Small populations were subsequently discovered in the 1890s and the total population was estimated to be about 100 individuals. Once protected, the elephant seal population started to rebound rapidl in US nad Mexico

In the early 1900s, the seal was given protection status by the United States and Mexico. Once protected, the elephant seal population started to rebound rapidl

Biodiverse habitats offer several types of economic benefits that motivate conservation efforts. each other to cycle nutrients through the environment.c cycling sustain enviro

Biodiverse habitats offer several types of economic benefits that motivate conservation efforts. Provisioning services provide useful products for human consumption. Regulating services control the climate and environmental conditions. Cultural services promote tourism through recreational attractions. Provisioning, regulating, and cultural services describe three types of economic benefits provided by natural environments. Provisioning services include the useful products that humans take from the habitat and consume. For example, forests provide humans with botanical products that have medicinal value as well as with lumber for building. Regulating services include the ways in which species control the climate and environmental conditions surrounding them. Photosynthetic organisms regulate Earth's climate by utilizing CO2 they remove from the atmosphere. Species affect their local environments by shaping the landscape. For example, some species of grass help prevent soil erosion. Cultural services include the aesthetic, spiritual, or recreational value of a natural environment. Cultural services can promote tourism through recreational attractions. Some communities rely on the economic activity of tourists who travel to see different environments or to interact with wildlife. A fourth category of economic benefit includes supporting services. Supporting services allow ecosystems to exist. For example, species interact with each other to cycle nutrients through the environment. These activities may not directly benefit human economies. Supporting services allow natural environments to exist. These instrumental uses of biodiversity directly affect human economies. In addition to being economically useful to humans, biodiversity also has intrinsic value. Many humans feel that preserving biodiversity is the ethically responsible thing to do, not because biodiversity benefits us, but because we would be wrong to destroy it. The intrinsic value of biodiversity does not take into account any economically valuable goods or services provided by an ecosystem.

New England cod An assessment in 2011 found that the cod population had been very slow to respond, and so limits were reduced even further for 2013 through 2016. , U.S. cod fishermen lobbied for higher cod quotas so that they could continue to make a living steady increase in the percent of collapsed fisheries, In contrast, collapsed fisheries occur in more than 25 percent of species assessed off the coast of the northeastern United States and more than 60 percent of species assessed off the coast of eastern Canada. Alaska few collapsed fisheries

By 2010, the U.S. government greatly reduced the amount of cod that could be caught by commercial anglers, in the hope that the population would rebound An assessment in 2011 found that the cod population had been very slow to respond, and so limits were reduced even further for 2013 through 2016. U.S. cod fishermen lobbied for higher cod quotas so that they could continue to make a living. However, the government biologists argued that if the cod limits were not lowered substantially, there would soon be no cod left to catch reducing the harvest of overharvested species has real economic impacts on those employed in the industry, failure to restrict the harvest hastens the decline of the species to levels at which there are no individuals left to harvest. There has been a steady increase in the percent of collapsed fisheries, and estimates are that approximately 14 percent of fisheries are now collapsed, eastern Bering Sea off the shores of Alaska, have very few collapsed fisheries. In contrast, collapsed fisheries occur in more than 25 percent of species assessed off the coast of the northeastern United States and more than 60 percent of species assessed off the coast of eastern Canada. Over the past 60 years, there has been a steady increase in the percent of fish and other seafood that are categorized as collapsed. (a) Around the world, 14 percent of assessed species are considered collapsed. including (b) a low percentage of collapsed fisheries in the eastern Bering Sea, (c) a modest percentage in the water off the coast of the northeastern United States, and (d) a high percentage off the coast of eastern Canada

Dioxin contamination led to whole town being evacuated and destroyed

Caused by waste oil contaminated with dioxin being spread on the roads to keep dust down Half life is 7-11 years Check it out online!

When a commercially important fish species no longer has a population that can be fished, it is called a collapsed fishery. Atlantic cod, a species of fish caught by commercial trawlers coast of Newfoundland in Canada, amount of cod caught from 1850 to 1960 slowly increased from 100,000 to 300,000 metric tons technologies—including advanced sonar, GPS, and larger trawlers—allowed a rapid increase in the number of cod caught, crashed to very low levels in the early 1990s, leading the Canadian government to close the fishery in 1992. government was under pressure from cod fishermen to allow continued fishing. agreed, but soon the number of fish fell so much that cod fishing had to be completely stopped and 35,000 New technologies in the 1970s and 1980s allowed much larger catches of cod, but this led to an overharvest of the fish and a collapse of the population in 1992 that persists today. 1850s to 60s , then collapsed again

Consider the case of the Atlantic cod, a species of fish caught by commercial trawlers. On the Grand Banks fishery off the coast of Newfoundland in Canada, the amount of cod caught from 1850 to 1960 slowly increased from 100,000 to 300,000 metric tons, as shown in Figure 22.14. During the 1970s and 1980s, new technologies—including advanced sonar, GPS, and larger trawlers—allowed a rapid increase in the number of cod caught, However, the population crashed to very low levels in the early 1990s, leading the Canadian government to close the fishery in 1992. Despite low cod numbers, the Canadian government was under pressure from cod fishermen to allow continued fishing. The government agreed, but soon the number of fish fell so much that cod fishing had to be completely stopped and 35,000 Canadian fishermen lost their livelihood. prediction is that the population may be able to be sustainably fished again by 2030 From 1850 to 1960, there was a slow increase in the catch of Atlantic cod by commercial fishermen off the coast of Newfoundland in eastern Canada. New technologies in the 1970s and 1980s allowed much larger catches of cod, but this led to an overharvest of the fish and a collapse of the population in 1992 that persists today.

Why is it difficult to identify all the species that will be driven extinct by global climate change? Current data do not allow for precise predictions of how temperature and precipitation patterns scientists do not know exactly what conditions species will face.

Current data do not allow for precise predictions of how temperature and precipitation patterns will change, so scientists do not know exactly what conditions species will face. not precise current data on temp and rain Climate models can provide information about general climate trends and predict large‑scale changes of the planet's warming. However, there are too many interrelated variables to accurately predict the weather patterns in specific locations. Furthermore, scientists cannot always predict species' movements or the consequences of weather. For instance, scientists can predict that sea levels will rise and hurricane frequency and intensity will increase. Scientists cannot predict that a hurricane will destroy the last remaining ghost orchid habitat before the rising sea inundates the area. Therefore, it is impossible to predict which species will become extinct due to climate change‑induced weather events. Species with populations small enough to be at risk of extinction often live in a small geographic area. A series of difficult local weather events could push such a species to extinction. The number of extinctions also depends on the amount of carbon dioxide humans continue to release into the atmosphere. Precise carbon dioxide records spanning thousands of years make it clear that the climate changes when the amount of carbon dioxide in the atmosphere fluctuates. The warmer the planet gets, the more difficult it will be for species to survive. Scientists can determine the temperature and precipitation requirements of different species fairly precisely. Global climate models give a general idea of how plant ranges will change as the planet warms. The models predict which areas near a species' current range will be suitable for the species in the future. As the climate changes, conditions will exceed some species' tolerances, and they will get pushed to extinction. Scientific evidence suggests that few present‑day extinctions happen by chance. The majority are human‑induced.

Global declines in genetic diversity declining population sizes, inbreeding, and bottleneck all animals that humans consume or use for labor, 7 mammals, 4 birds, 150 species of plants; just 12 species make up the vast majority of people's diet

Declines in genetic diversity can be caused by declining population sizes, inbreeding depression, and the bottleneck effect. Declines can reduce the probability that a population is able to survive changing conditions (e.g., climate, emerging infectious diseases). Humans need genetic diversity; all animals that humans consume or use for labor include just seven mammal species and four bird species. Likewise, humans consume only about 150 species of plants; just 12 species make up the vast majority of people's diets (e.g., wheat, rice, and corn).

spp intervention intervening condor hunting Scientists found that females produce more if eggs are removed from the nest and offspring are reared away from the mother.

Example: California condors declined in abundance during the twentieth century due to human-related causes (e.g., illegal shooting). In the 1980s, researchers brought all remaining birds into captivity. Scientists found that females produce more if eggs are removed from the nest and offspring are reared away from the mother. Birds were reintroduced and populations have begun to rebound. Reintroductions are costly, but efforts to save one species can have positive effects on many other species.

Government regulates harvests; regulations must balance the benefit of conserving species with the economic benefits to humans. new technologies allowed a large increase in the number of Atlantic cod in Newfoundland cod crashed to very low levels in 1990s Canadian government attempted to ban, cod fisherman lobbied the government quick collapse, 35,000 fishermen lost their livelihood. 20 yr after closing rebound

Example: During the 1970s and 1980s, new technologies allowed a large increase in the number of Atlantic cod caught off the coast of Newfoundland in Canada. The population crashed to very low levels in 1990s, and the Canadian government attempted to ban cod fishing to allow populations to rebound. However, cod fisherman lobbied the government to allow fishing; the cod population quickly crashed and 35,000 fishermen lost their livelihood. The government closed the fishery in 1992; populations began to rebound in 2012.

Reduced crop genetic diversity reduces options to respond to environmental conditions and challenges (e.g., plant pathogens).

Example: In the 1970s, a fungus killed half the corn in the southern United States because all plants came from a single variety. Fortunately, a fungus-resistant corn variety was available. To protect seed diversity from natural disasters, the Svalbard Global Seed Vault was constructed in the Arctic region north of Norway.

Introductions of species can be both intentional and accidental. Only about 5% of introduced species become established in a new region, but those that do have a variety of effects. Some species provide important benefits (e.g., the common honeybee); others can have negative effects on native species.

Example: The silver carp was brought to the United States in 1970s to control algae in water treatment and aquaculture facilities; it escaped captivity in the 1980s and is spreading to many water bodies. Because it is a voracious algal consumer, it may compete with native species. The carp also tend to jump out of the water, which poses a risk to boaters.

Human technology has allowed us to harvest species at more rapid rates and drive some species to extinction. archaeological sites in the Mediterranean , changed their diets as different foods were depleted humans on Madagascar , extinction of 14 lemur species and 6 to 12 species of large, flightless birds.

Extinction by hunting and fishing is not a recent phenomenon. Examples: Skeletal remains of animals in archaeological sites in the Mediterranean region suggest that early humans changed their diets as different foods were depleted over time. Fifteen hundred years ago, the arrival of humans on Madagascar caused the extinction of 14 lemur species and 6 to 12 species of large, flightless birds.

Why is it important to preserve genetic diversity within a species?

High levels of genetic diversity help species adapt to changing environmental conditions. Individuals in a genetically diverse species have many different genotypes. Each genotype produces different traits and qualities. These differences between individuals allow a species to adapt to changing environmental conditions. The individuals that are genetically equipped to survive the change in conditions will reproduce and keep the species alive. n environmental stress that harms one member of the species will likely affect each member of the species in the same way. Individuals within a species with high genetic diversity are not all naturally resistant to every infection. In a genetically diverse population, some individuals may have genotypes that can resist the current infection. Other individuals may be more susceptible.

To gain insight into the global scale of habitat change, researchers have assessed how forests have been changing in more modern times. For the period 2001-2018, continued loss of forests has occurred in many regions, including the Amazon and Southeast Asia The species composition that currently exists in regions that have experienced an increase in forest cover, is often quite different from what existed originally,

However, there has been an increase in several forests in the United States, Europe, and northern Asia. You can view a map of these changes in Figure 22.12. The species composition that currently exists in regions that have experienced an increase in forest cover, is often quite different from what existed originally, particularly in cases where a single species of tree is planted due to its high commercial value.

mammal fossils from 30 Mya to 500 years ago to create species-area curves curve after human arrival were significantly lower humans coincided with a 15% to 42% decline in mammal diversity. in North America animals extinct, climate change, hunting and disease

Human impacts on diversity can be seen far back in time, starting with the arrival of humans 10,000 years ago. Example: Researchers used mammal fossils from 30 Mya to 500 years ago to create species-area curves for different regions in North America before and after human arrival. Species-area curves for the period after human arrival were significantly lower than curves for the period before human arrival. north America mammal decline Arrival of humans coincided with a 15% to 42% decline in mammal diversity. Explanations for extinctions include climate change following glacial retreat, human hunting pressure, and epidemic diseases carried by domesticated animals.

modern livestock operations favor relatively few breeds. for many traits, big if need to breed new varieties that can live in novel environments.

Humans have bred livestock species for a wide variety of different traits (e.g., size, strength, quality of meat). Many livestock varieties have not been maintained; modern livestock operations favor relatively few breeds. Ten percent of all domestic bird breeds have gone extinct and another 21% are at risk. Reduced livestock genetic diversity provides less diversity to us if we need to breed new varieties that can live in novel environments.

Which of the following is true of global declines in genetic diversity?

Humans once consumed 7000 species of plants, today humans consume only 150 species.

For example, the instrumental value of biodiversity focuses on economic values that species can provide, such as lumber for building or crops for eating. DONT

In contrast, the intrinsic value of biodiversity recognizes that species have inherent value that is not tied to any economic benefit. can have both

Identify each statement as an example of the instrumental or intrinsic value of biodiversity in species and ecosystems. Provisioning=products

Instrumental value Penicillium fungi produce several families of penicillin antibiotics. Millions of people visit the Grand Canyon each year. The oceans absorb tons of the carbon dioxidegiven off from human activity. Intrinsic value Maryland's citizens are concerned that their state bird, the oriole, is disappearing. Moral responsibility has led the U.S. to establishhundreds of wildlife refuges. Humans place value on Earth's species and ecosystems for various reasons and to different degrees. The biodiversity of species and ecosystems can have instrumental value, intrinsic value, or both. Humans assign instrumental value to four types of services that provide economic benefits. Provisioning services provide humans with products, such as ores, water, crops, and antibiotics including penicillin. Regulating services, such as climate modification, contribute to the wellbeing and balance of the planet. Cultural services include recreational or aesthetic benefits, such visiting the Grand Canyon. Supporting services provide the conditions necessary to maintain life, such as when oceans absorb excess carbon dioxide. Humans place intrinsic value on benefits that are not tied to economics. Rather, the value is based on a feeling of moral or ethical conviction that every species and ecosystem has an inherent value. The oriole and wildlife refuge scenarios are examples of items of intrinsic value.

Values of biodiversity

Intrinsic value of biodiversity: a focus on the inherent value of a species, not tied to any economic benefit. People who place intrinsic value on biodiversity feel religious, moral, or ethical obligations to preserve the world's species. It is difficult to prioritize conservation efforts based on intrinsic values. Instrumental value of biodiversity: a focus on the economic value a species can provide (e.g., the value of lumber and crops). Many species remain undiscovered, so the value of species and ecosystems can be difficult to estimate. Benefits of diversity are estimated at $319 billion per year in the United States, and globally at $3 trillion to $54 trillion per year.

What makes the sixth mass extinction unique?

It is being caused by an organism.

Recreation does not have to be banned from condor habitats as long as human access to nesting sites is restricted allowed recreation in preservation of large tracts of habitat and steel Legal hunting bullets and ranching

Legal hunting doesn't harm condors as long as steel rather than lead bullets are used Finally, ranching does not threaten condor populations so long as coyote and rodent control programs are condor-safe.

Why is the area allocated for protecting marine ecosystems worldwide less than the area allocated for protecting terrestrial ecosystems?

Marine ecosystems began receiving protection much later.

Overharvesting of species continues into modern times. Illegal species trade is valued at $5 billion to $20 billion annually. Collapsed fisheries occur in more than 25% of species assessed off the coast of the northeastern United States.

Modern fishing techniques (long fishing lines, large nets, trawlers) have increased the number of fish and shellfish caught. Overfishing has led to an increase in the number of collapsed fisheries, or fishing areas that no longer have populations that can be fished. Collapsed fisheries occur in more than 25% of species assessed off the coast of the northeastern United States.

Humans historically consumed more than 7,000 species of plants, but today consume only about 150 species. 12 species of plants make up the vast majority of people's diets; among these are wheat, rice, and corn In earlier times, humans bred varieties that grew well and small farms gave way to much larger operations that greater competitor on farms? less harsh enviro in modern agriculture U.S. farmers grew about 8,000 varieties of apples in 1900, 95 percent of these varieties are extinct. in the 1970s, a fungus attacked cornfields in the southern United States and killed half the corn crop because the plants all came from a single variety. The loss of the corn crop was estimated to be $1 billion 70s lost half corn crop another variety of corn possessed a fungus-resistant gene,

Moreover, just 12 species of plants make up the vast majority of people's diets; among these are wheat, rice, and corn. In some cases—for example, corn—modern varieties look very different from their ancestors (Figure 22.8). In earlier times, humans bred varieties that grew well under particular local environmental conditions. However, as agricultural practices changed, irrigation and fertilizer made it possible to reduce the harshness of the growing environment, and small farms gave way to much larger operations that favored only the top-producing crop varieties greater competitor on farms? less harsh enviro In addition new varieties have been bred that have improved disease resistance or improved flavor many of the older, local varieties of crops are no longer available. For example, U.S. farmers grew about 8,000 varieties of apples in 1900, but today, 95 percent of these varieties are extinct. (a) Corn originated from a wild plant in Mexico, known as teosinte, shown on the left. Modern cultivated corn is shown on the right. An ear of the F 1 hybrid is shown in the center. (b) From the teosinte ancestor, humans have bred a wide range of genetic varieties to perform well under different conditions,m Mexican corn from teosinte less diversity reduces our options when we need to respond to challenges such as new pathogens that attack a crop. For example, in the 1970s, a fungus attacked cornfields in the southern United States and killed half the corn crop because the plants all came from a single variety. The loss of the corn crop was estimated to be $1 billion. Fortunately, another variety of corn possessed a fungus-resistant gene, and breeders were able to produce a new variety that is resistant to the fungus. To protect the genetic diversity of plant varieties, many countries have been archiving seed varieties of different crop species in storage facilities around the world Concern that such facilities could be destroyed by natural disasters or war led to the construction of the Svalbard Global Seed Vault. Located on an island in the Arctic region north of the Norwegian mainland, the facility is a 125-m tunnel built into a mountain with rooms for seeds on each side of the tunnel, This facility protects seeds from virtually all catastrophes. The vault has a total capacity of 1.5 million samples; as of 2019, the facility contained more than 950,000 samples of crop seeds from nearly every country. preserve the ability to call upon the genetic diversity of plant species far into the future.

Half-life: the time required for a chemical to break down to half of its original concentration; helps to determine if contaminants persist in the environment and affect organisms.

Most chemicals have a breakdown rate that follows a negative exponential curve. When we do not have a graph to calculate a half-life, we can use the equation:

group the instrumental values of biodiversity into four categories of services: provisioning, regulating, cultural, and supporting. provisioning, cultural, supporting, regulating Provisioning provide products humans use, plants and animals cultivated to ENHANCE their valuable qualities and pharmaceutical chemicals Taxol to fight cancer. now used from Pacific yew tree Regulating services, climate regulation, flood control, and water purification wetlands absorb large amounts of water and so prevent flooding also remove contaminants from the water and make it more suitable for drinking. The CO 2 that is taken out of the air by producers on land 4 gigatons are taken out of the air by producers, which reduces the effect humans have on global temperatures due to global warming., of 8 tons put in Cultural services are benefits of biodiversity that provide aesthetic, spiritual, or recreational value areas are preserved because income from tourists can exceed what would be received from clearing intrinsic values of biodiversity do not provide any economic benefits to humans moral obligation saving bald eagle

Provisioning services are benefits of biodiversity that provide products humans use, including lumber, fur, meat, crops, water, and fiber. plants and animals from the wild have been cultivated or domesticated and then selectively bred to ENHANCE their valuable qualities. Provisions also include pharmaceutical chemicals that come from plants and animals 70 percent of the top 150 pharmaceutical drugs originate in chemicals that nature produces which is used to fight cancer. Today, Taxol is synthesized in the laboratory, but it originally came from the Pacific yew tree This single chemical currently generates more than $1.5 billion in annual sales around the world Over the past 25 years, more than 800 natural chemicals have been identified in the search to provide treatments for everything from cancer to contraception, and there is no indication that the pace of these discoveries is slowing down. Regulating services are benefits of biodiversity that include climate regulation, flood control, and water purification not for mateiral provisions For example, wetlands absorb large amounts of water and so prevent flooding from water runoff during rainy periods. plants living in the wetlands also remove contaminants from the water and make it more suitable for drinking. The CO 2 that is taken out of the air by producers on land and in the ocean is another regulating service wetlands, plants, Of the 8 gigatons of carbon that are put into the air each year by human activities, about 4 gigatons are taken out of the air by producers, which reduces the effect humans have on global temperatures due to global warming. Cultural services are benefits of biodiversity that provide aesthetic, spiritual, or recreational value For example, cultural services include the benefits that people obtain when they go hiking, camping, boating, or birdwatching. People pay to visit beautiful natural areas, such as the Florida Everglades in the United States or Banff National Park in Canada. areas are preserved because income from tourists can exceed what would be received from clearing a forest or from using the land for housing and industry. tropic attraction captizlied by establishing parks and support services for tourists. In Palo Verde National Park in Costa Rica, for example, monkeys and beautiful tropical birds draw tourists to areas where the species are protected Diversity itself is often the attraction in tropical rainforests and coral reefs Supporting services are benefits of biodiversity that allow ecosystems to exist, such as primary production, soil formation, and nutrient cyclin There would be no ecosystems without producers that capture the energy of the Sun and then transfer it to all other trophic levels. actual production itself, supporting existence of system, thru diversity? In contrast to instrumental values, the intrinsic values of biodiversity do not provide any economic benefits to humans. Instead, people who place intrinsic value in biodiversity feel religious, moral, or ethical obligations to preserve the world's species. For example, a major motivation for efforts to bring back the bald eagle from the brink of extinction in the 1970s was that it was the national symbol of the United States and we had a moral obligation to prevent its extinction very difficult to prioritize conservation efforts only by arguing that all species are intrinsically valuable. In reality, we can consider both instrumental and intrinsic values when deciding how to focus our conservation efforts.

services: provisioning(humans use), supporting(allow ecosystems to exist), regulating(climate regulation, flood reg) cultural( aesthetic, spiritual, or recreational value),

Provisioning services: Benefits of biodiversity that humans use, including lumber, fur, meat, crops, water, and fiber. Example: The drug Taxol, which is used to fight cancer, was first derived from the Pacific yew tree and now has more than $1.5 billion in annual sales; more than 800 pharmaceutical chemicals have been derived from natural origins. Regulating services: Benefits of biodiversity that include climate regulation, flood control, and water pollution. Example: Wetlands absorb water and prevent flooding during rainy periods; wetland plants remove contaminants from water, which makes it more suitable for drinking. Cultural services: benefits of biodiversity that provide aesthetic, spiritual, or recreational value (e.g., hiking, camping). Example: Income from tourists can exceed what would be received from clearing a forest or from using land for housing or industry. In Palo Verde National Park in Costa Rica, beautiful tropical birds (e.g., the resplendent quetzal) and monkeys generate ecotourism. Supporting services: benefits of biodiversity that allow ecosystems to exist (e.g., primary production, soil formation, and nutrient cycling).

For a graduate school study, you record plant species richness in grassland biomes in five African countries: Kenya, Nigeria, Uganda, South Africa, and Egypt. You find that plant species richness in Kenya is 15, in Nigeria, 11; in Uganda, 17; in South Africa, 21; and in Egypt, 16. Based on the results of the similar study comparing plant aboveground biomass to species richness throughout Europe, in which of these African countries would you predict that plants' aboveground biomass would be highest?

South Africa

The amount of terrestrial habitat that is being protected has continually increased over the past 40 years, as shown in Figure 22.23a. In fact, 57 percent of the world's countries have protected at least one-tenth of their land. Though the need to protect marine habitats has been recognized much more recently, as you can see in Figure 22.23b, it has also increased over time. 57 percent of the world's countries have protected at least one-tenth of their land. Terrestrial protection has increased over the past 40 years, amount of protected marine habitats has also grown over time. but marine protection much later countries cannot afford to protect them from squatters and poachers local people in the design and management of protected areas has been particularly effective

Terrestrial ecosystems have a longer history of being protected, and this level of protection has increased over the past 40 years. (b) Marine ecosystems began receiving protection much later, but the amount of protected marine habitats has also grown over time. Even when lands are set aside, many countries cannot afford to protect them from squatters and poachers, and often governments allow mining and logging within protected lands. However, involving local people in the design and management of protected areas has been particularly effective since the benefits of conservation, which often include the income generated by ecotourism, become tangible and economically compelling

Habitat loss->fragmentation Tallgrass prairie, 69 to 4% left wetlands, draining for human use has reduced this area in half.

The destruction and degradation of habitat has been the largest cause of declining biodiversity. Example: Only a small fraction of the Atlantic forest along the Brazilian coast remains after decades of intense forest clearing. Deforestation has endangered endemic species (e.g., the golden lion tamarin). In modern times, there has been continued loss of forests in many regions, and an increase in forests in other regions. Many other habitats have changed as a result of human activities. Examples: Tallgrass prairie covered 69 million ha in North America; less than 4% remains. In the 1600s, wetlands covered more than 89 million ha in the lower 48 states; draining for human use has reduced this area in half. Habitat loss leads to fragmentation and smaller populations that are more likely to go extinct. Fragmented areas have more edge habitat that can alter abiotic conditions of the interior habitat and favor edge species. Example: The bronzed cowbird prefers edge habitat, but parasitizes on bird species in forest interior.

largest contributor to the loss of biodiversity is the loss of habitat, one of the major factors in conserving biodiversity has been habitat protection. LARGEST cause of loss of biodiversity is the LOSS of habitat enough area to support a minimum viable population (MVP),-smallest population that can persist with environmental variation population must also be distributed widely enough into sub pops population subdivision may help prevent the spread of disease MAYBE not best conservation plots, want one big one , but spreading out for many reasons

The goal in protecting a habitat is commonly the preservation of a large enough area to support a minimum viable population (MVP), which is the smallest population size of a species that can persist in the face of environmental variation The population must also be distributed widely enough to prevent local catastrophes, from threatening one species some degree of population subdivision may help prevent the spread of disease if in sub pops

introduced species has increased ->. Biotic homogenization:, species compositions originally found in different regions slowly become more similar us moving stuff and sleeved

The number of introduced species has increased over time. Example: Researchers compiled data on introduced species since 1900 for Nordic countries. More than 1,600 species have been introduced across terrestrial, freshwater, and marine ecosystems. Biotic homogenization: the process by which unique species compositions originally found in different regions slowly become more similar due to the movement of people, cargo, and species.

As a biocontaminant enters an ecosystem, biomagnification causes it to become more concentrated. Order the five components of the system from least concentrated to most concentrated. . The zooplankton accumulate the contaminant in their fatty structures as eating level below in food chain continue to build up/accumulate the contaminant found in each of the primary consumers, in fatty tissues Because the contaminant increases in concentration with each successive consumer in the food chain the concentration of the contaminant is biomagnified

The process of biomagnification occurs as fat‑soluble contaminants move up the food chain and become increasingly concentrated within each trophic level. Contaminants are incorporated into the fatty tissues of consumers that eat contaminated prey. Contaminants enter a water system and accumulate on tiny particles, including phytoplankton. on algae/plankton Primary consumers, such as zooplankton, eat many, many phytoplankton. The zooplankton accumulate the contaminant in their fatty structures. This results in higher concentration of the contaminant in the zooplankton than was in the phytoplankton. This biomagnification continues up the food chain as secondary consumers, such as fish, eat large quantities of the contaminated primary consumers. The secondary consumers accumulate the contaminant found in each of the primary consumers, resulting in a higher contaminant concentration in the secondary consumers than in the primary consumers. Finally, the tertiary consumers, such as great blue heron, consume many secondary consumers, such as fish. Once again, the contaminant accumulates at a higher concentration in the tertiary consumers than was found in the secondary consumers. Because the contaminant increases in concentration with each successive consumer in the food chain, the concentration of the contaminant is biomagnified by the food chain.

Over time, if species that are poorly adapted to coexist with humans die off and species that are well adapted to coexist with humans survive and increase in abundance, which of the following will occur?

The ratio of species of least concern to threatened species will increase.

provisioning services

benefits of diversity humans use like lumber, tree crops , fur water fiber, yew tree taxol 1 bil in national sales caffeine

Climatic differences between biomes will likely limit the extent to which _____ can ultimately influence global biodiversity.

biotic homogenization

Global declines in species diversity bird , conifer, fish , mammal, amphibians flowering plant species, reptiles, and insects have NOT been assessed 46% to 74% of assessed species are threatened., lots are threatened that we know of

The risk of a sixth mass extinction depends on how many species go extinct during the next few centuries. The International Union for Conservation of Nature (IUCN) defines categories that describe the extinction risk for a species: Extinct: the animal was known to exist in the year 1500, but no individuals remain alive today. Extinct in the wild: the only individuals remaining are in captivity. Threatened: species at high risk of extinction; endangered species. Threatened=endangered Near-threatened: species likely to become threatened in the future. Least-concern: species with abundant populations. Data are insufficient to make reliable determination for many species. not soil microbes we don't care

During the first mass extinction, about 440 Mya, most species lived in the oceans. An ice age caused sea levels to drop and the ocean chemistry to change, which resulted in 86 percent of species going extinct. The second mass extinction happened 360 Mya when much of the ocean lacked oxygen—for reasons that are unclear—and 75 percent of all species went extinct. multiple hypotheses to explain this third mass extinction, we are still uncertain about the cause., 96 percent of all species then present on Earth went extinct. fourth mass extinction, 80 percent of the world's species to go extinct. , volcanic activity, asteroid collisions with Earth, and climate change. olcanic eruptions and changes in climate caused long periods of cold weather, then asteroid explosion put so much dust into the atmosphere that it blocked the Sun's rays past 3.5 billion years, it is estimated that 4 billion species have existed on Earth and 99 percent of these species are now extinct overall, the number of species has increased with time, new species evolved after each mass extinction even

The second mass extinction happened 360 Mya when much of the ocean lacked oxygen—for reasons that are unclear—and 75 percent of all species went extinct. first 2 mass extinction-chem change and then oxygen change During the third mass extinction—250 Mya—an astounding 96 percent of all species then present on Earth went extinct. Although researchers have constructed multiple hypotheses to explain this third mass extinction, we are still uncertain about the cause. The fourth mass extinction, which occurred about 200 Mya, caused 80 percent of the world's species to go extinct. Hypotheses for the causes of this fourth extinction include increased volcanic activity, asteroid collisions with Earth, and climate change. First, volcanic eruptions and changes in climate caused long periods of cold weather. This was followed by a massive asteroid that struck the Yucatan Peninsula in Mexico The fifth mass extinction happened 65 Mya and is best known as the one that led to the extinction of dinosaurs. struck with a force more than 1 billion times that of the atom bomb dropped on Hiroshima during World War II Scientists hypothesize that the explosion put so much dust into the atmosphere that it blocked the Sun's rays, making Earth much less hospitable to dinosaurs along with many other groups, such as flowering plants. During this time, 76 percent of the species on Earth went extinct. n fact, over the past 3.5 billion years, it is estimated that 4 billion species have existed on Earth and 99 percent of these species are now extinct after each mass extinction event, new species evolved and, overall, the number of species has increased with time

instrumental value total economic benefit of biodiversity $319 billion per year. For perspective, this is about 10 percent of U.S. annual gross domestic product

The total economic benefit of biodiversity is difficult to estimate because many of the world's species remain undiscovered and the values of each species and ecosystem themselves can be difficult to estimate For example, the total economic benefit of biodiversity in the United States is estimated at $319 billion per year. For perspective, this is about 10 percent of U.S. annual gross domestic product

intro Lecture ConceptsLecture Concepts

The value of biodiversity arises from social, economic, and ecological considerations. Although extinction is a natural process, its current rate is unprecedented. Human activities are causing the loss of biodiversity. Conservation efforts can slow or reverse declines in biodiversity.

Habitat protection habitats must be large enough to support a minimum viable population Minimum viable population (MVP): the smallest that can persist in the face of environmental variation. changing climate persevering seasonal habitat Preservation of only one section of the Serengeti

To slow declines in biodiversity we must stabilize the size of the human population and reduce human-caused sources of mortality. Habitat protection is important; habitats must be large enough to support a minimum viable population and to prevent local catastrophes from threatening an entire species. Minimum viable population (MVP): the smallest population size of a species that can persist in the face of environmental variation. The habitat needs of a population change with seasons. Example: Wildebeests, zebras, and gazelles in the Serengeti migrate in search of grazing area as rainfall patterns change through the seasons. Preservation of only one section of the Serengeti would not meet their needs. For species that migrate, large tracts of land need to be set aside, managed, and protected (e.g., from squatters and poachers). Example: The Yellowstone Ecosystem is being managed to keep the area in a natural, self-sustaining condition. Fires are allowed to burn and top predators are being restored. Today, 57% of the world countries have protected at least one-tenth of their land.

The current rapid decline in biodiversity is caused by the rapid increase in human populations and the many activities of humans 35 percent of the land area is used for crops or permanent pastures temperate latitudes that are suitable for agriculture have been plowed or fenced, sub-Saharan Africa, have been turned into deserts by overgrazing most old-growth forests were cut down in the eighteenth century and only a fraction of the original forests remain today. younger=dif spp in forest deforestation has critically endangered many endemic birds and mammals, intense conservation efforts have focused on saving them from extinction by protecting what little habitat remains The island of Sumatra was once widely covered in forests. Even during the past few decades, much of the forest has been cleared. Today, only a small fraction of the island contains intact primary forest

Virtually all areas within temperate latitudes that are suitable for agriculture have been plowed or fenced, 35 percent of the land area is used for crops or permanent pastures, and countless additional hectares are grazed by livestock Semiarid subtropical regions, particularly in sub-Saharan Africa, have been turned into deserts by overgrazing and harvesting firewood. Rivers and lakes are badly contaminated in many parts of the world. Gases from chemical industries and the burning of fossil fuels pollute our atmosphere The destruction and degradation of habitat have been the largest cause of declining biodiversity. In the United States, for example, most old-growth forests were cut down in the eighteenth century and only a fraction of the original forests remain today. Of course, many of these forests have regrown. Logging of these new forests has typically continued using sustainable practices, although these younger forests do not provide habitat to all the same species as the original old-growth forests did. younger=dif spp in forest humans have cleared large forests on the island of Sumatra in Southeast Asia, s such that only a small fraction of the original forest remains, This deforestation has critically endangered many endemic birds and mammals, such as the Sumatran tiger (Panthera tigris sumatrae), the Sumatran ground cuckoo (Carpococcyx viridis), and the Sumatran orangutan (Pongo abelii; Figure 22.11). Because such endemic species live nowhere else in the world, intense conservation efforts have focused on saving them from extinction by protecting what little habitat remains The island of Sumatra was once widely covered in forests. Even during the past few decades, much of the forest has been cleared. Today, only a small fraction of the island contains intact primary forest (i.e., forests that have not been logged) and degraded primary forest (i.e., forests that have experienced some amount of logging).

Global climate change sea level has risen ~3 mm per year. over 2 dec, 0.2 m total

Warming has had a number of effects, such as a reduction in ice mass in Antarctica. Ice melting has led to a 0.2 m sea level increase in 140 years; in the past 20 years, sea level has risen ~3 mm per year. Warming has led to shifts in the timing of many ecological events (e.g., breeding, pollination), and shifts in the range of many species. It is difficult to predict future global climates; the outcome will partly depend on how much CO2 is added to the atmosphere.

Which of the taxonomic groups has the highest percentage of species considered to be of least concerned?

birds

22.2 The current rate of extinction is unprecedented 1.3 million species have received Latin names, 15,000 new species are described annually most scientists agree that there are about 10 million species declining in abundance and facing extinction need to understand the historic versus modern rates of extinctions. mass extinction events, which are defined as events in which at least 75 percent of the existing species go extinct within a 2-million-year period. a significant decline in the number of families, which also means there were major declines of genera and spp The fifth extinction is hypothesized to have been caused by volcanic eruptions, cooler climates, and a massive asteroid that struck the Yucatan

We do know that 1.3 million species have received Latin names and about 15,000 new species are described each year. depending on the assumptions used, most scientists agree that there are about 10 million species. Some species are declining in abundance and facing extinction as humans continue to alter terrestrial and aquatic ecosystems However, as we have seen throughout this book, some extinctions are natural. Therefore, we need to understand the historic versus modern rates of extinctions. human or natural extinctions In this section, we will explore the past and present rates of extinction and then examine how specific groups of organisms are faring Over the past 500 million years, the world has experienced five mass extinction events, which are defined as events in which at least 75 percent of the existing species go extinct within a 2-million-year period. many f species, genera, and families around the world went extinct During these periods, the world experienced a significant decline in the number of families, which also means there were major declines in the number of genera and species. s. Continued speciation during subsequent years has helped to offset these extinctions. (b) The fifth extinction is hypothesized to have been caused by volcanic eruptions, cooler climates, and a massive asteroid that struck the Yucatan Peninsula and put massive amounts of dust into the air that blocked the Sun's rays. volcano, cold, Yucatan asteroid

22.4 Conservation efforts can slow or reverse declines in biodiversity we need to stabilize the size of the human populatio reduce sources of mortality and low reproduction in species

We have seen that human activities have caused a decline in the world's biodiversity. We now look at what can be done to slow or even reverse these declines. . Over the long term, we need to stabilize the size of the human population because human activities have caused most species declines during the past several centuries. Over the short term, we need to reduce sources of mortality and low reproduction in species that have been caused by humans so that these species can persist

When this pesticide enters a water body, it binds to particles including algae and becomes about 10 times more concentrated than it is in the water. algae are consumed by zooplankton, DDT accumulates in fat tissues 800 times higher than in the water increase in concentration of a contaminant up the food chain=biomagnification when a fish-eating bird such as an osprey consumes a large fish, DDT becomes concentrated another 10-fold. top of the food chain, the insecticide is 276,000 times more concentrated in the body of the fish-eating bird than it was in the water causes the eggs they lay to have very thin shells. from high DDT insecticides have since been developed that do not persist and are not stored in the fat of animals

When the algae are consumed by zooplankton, DDT accumulates in fat tissues and the zooplankton accumulate a concentration that is about 800 times higher than in the wate The increase in concentration of a contaminant as it moves up the food chain is known as biomagnification When small fish eat the zooplankton and large fish eat the small fish, DDT is further concentrated, by about 30-fold plankton to large 30-fold magnif Finally, when a fish-eating bird such as an osprey consumes a large fish, DDT becomes concentrated another 10-fold. In short, at the top of the food chain, the insecticide is 276,000 times more concentrated in the body of the fish-eating bird than it was in the water Such a high concentration in predatory birds interferes with their physiology in a way that causes the eggs they lay to have very thin shells. When the parents sit on these thin-shelled eggs, the eggshells break, and the embryos die. T When DDT was widely used to control insects, it could be found in very low concentrations in the water. However, its concentration increases in particles with which it binds in the water, such as algae. e. At each higher trophic level, the insecticide becomes more concentrated. Fortunately, alternative insecticides have since been developed that do not persist and are not stored in the fat of animals and, therefore, do not biomagnify through a food web ith the help of many biologists who hand-reared hundreds of predatory birds, populations of species such as the peregrine falcon and bald eagle have rebounded. DDT is still used in many tropical countries, although now in a limited manner, such as in houses to control the mosquitoes that carry malaria.

Moreover, some of the animals the condor scavenged and consumed contained lead bullet fragments or, in the case of coyotes and rodents, had been poisoned. condor scavenged poisoned prey with bullets biologists made the difficult decision to bring the entire population into captivity 22 remaining wild birds were captured and brought to special breeding facilities in LA and SD

When the condor population in southern California sank to fewer than 30 individuals in the late 1970s, biologists made the difficult decision to bring the entire population into captivity . From 1982 to 1987, the 22 remaining wild birds were captured and brought to special breeding facilities located at zoos in Los Angeles and San Diego

global temperatures are already affecting species. In Chapter 7, we discussed how many species of plants now flower earlier in the spring than they did in past decades and how some species of birds and amphibians now breed earlier in the year than they once did. In Chapter 10, we saw that warming ocean temperatures have caused a major shift in the fish species that live in the North Sea. birds and amphibians now breed earlier warming sea, major shift in the fish species that live in the North Sea. the temperature of water in the Gulf of Alaska rose by cause young cod to survive poorly. ALASKS but best fisheries same oceanic heat wave lead to the largest amount of death in sea birds ever recorded the fish they normally prey on moved down into deeper and cooler waters. travel farther to find sufficient ice extreme weather events such as hurricanes and droughts to occur more frequently

While global climate change has not yet led to the widespread extinction of species, its impacts on the performance of species is pervasive. For example, starting in 2014, the temperature of water in the Gulf of Alaska rose by 2 - 3 ° C , which was enough to cause young cod to survive poorly. . The persistence of this warmer water caused the U.S. government to ban cod fishing in 2019.' This same oceanic heat wave lead to the largest amount of death in sea birds ever recorded during 2016-2017; nearly one million birds died, primarily from a lack of food because the fish they normally prey on moved down into deeper and cooler waters. Arctic animals that depend on having ice for hunting are having to travel farther to find sufficient ice plants are flowering earlier, birds are migrating earlier, and amphibians are breeding earlier than they did several decades ago. large increase in CO 2 will raise temperatures by an additional 7 ° C . Researchers predict that these changes will cause extreme weather events such as hurricanes and droughts to occur more frequently. In addition, some regions of the world will receive more annual precipitation than is currently typical while other regions will receive less. Although specific predictions vary with different models, the distributions of organisms in nature will probably shif

greenhouse effect and how gases such as water vapor, CO 2 , methane, and nitrous oxide allow our planet to be warmed naturally by absorbing infrared radiation emitted by Earth and then reradiating a portion back toward Earth gases used as refrigerants known as chlorofluorocarbons (CFCs). pattern of increasing temperatures is clearer when we examine the 5-year-running mean temperatures. Temperature anomaly is a comparison of each year's temperature to avg over 3ish decades examined water gauges for ocean tides since 1870 and, as expected, have observed a steady increase in sea level .3 m every 100 years, which is enough to dramatically affect habitats on islands and along coastlines.

as well as the gases used as refrigerants known as chlorofluorocarbons (CFCs). One result of the increase in greenhouse gases has been an increase in the average temperature on Earth. Because of year-to-year variation in temperatures, the pattern of increasing temperatures is clearer when we examine the 5-year-running mean temperatures. Temperature anomaly is a comparison of each year's temperature compared to the mean temperature observed from 1951 to 1980 we might expect warmer temperatures to cause more of the world's ice to melt. From 1979 to 2019, the polar ice cap that exists between the United States, Canada, Europe, and Russia has declined by 42 percent Similarly, the decline in ice from 2002 to 2017 has been more than 1,800 metric gigatons for Antarctica and more than 3,800 gigatons for Greenland. You can view these data in parts b and c of Figure 22.20. All of this melting ice, combined with an overall warming of the oceans that causes water to expand, should cause a rise in sea levels Researchers have examined water gauges for ocean tides since 1870 and, as expected, have observed a steady increase in sea level. From 1993 to 2019, the sea level has been rising more than 3 mm per year, .3 m every 100 years, which is enough to dramatically affect habitats on islands and along coastlines.

In 2013, researchers examined predation by free-ranging domestic cats in the United States and found that the cats killed 1.4 to 3.7 billion ? and 7 to 21 billion mammals each yea movement of people, cargo, and species continues among the regions of the world unique species compositions originally found in different regions are slowly becoming more similar, a process known as biotic homogenization.

birds and mammals As the movement of people, cargo, and species continues among the regions of the world, the unique species compositions originally found in different regions are slowly becoming more similar, a process known as biotic homogenization.

We have seen that a mass extinction is defined as the extinction of 75 percent of species within a 2-million-year period. It is a widely held view in the scientific community that the increase in the human population during the past 10,000 years may have initiated a sixth mass extinction event we see that the current extinction rate exceeds the historic extinction rate. for mammals during the most recent 500 years extinction rate for mammals during the most recent 500 years is compared current extinction rate exceeds the historic extinction rate. 1,000 times higher than the historic rate based on a rich fossil history of mammals, researchers have defined different geographic regions and determined the number of fossil species in each created species-area curves for different time periods in North America, species-area curve for the period after human arrival—11,500 to 500 years ago—is significantly lower declining S-A curve with human arrival from 11,500 to 500 years ago (i.e., after humans arrived), the number of mammals declined anywhere from 15 to 42 percent,

compare prior extinction rates mammals, for which there are very good fossil data on extinctions. When the extinction rate for mammals during the most recent 500 years is compared to the rate of mammal extinctions over 500-year intervals in the past, we see that the current extinction rate exceeds the historic extinction rate. In fact, the United Nations Convention on Biological Diversity estimates that the extinction rate during the last 50 years has been as much as 1,000 times higher than the historic rate from the Industrial Revolution to today—a time in which we have drastically altered our world. However, human impacts on biodiversity can be seen much farther back in time. For example, based on a rich fossil history of mammals, researchers have defined different geographic regions of North America and determined the number of fossil species in each region. With these data they created species-area curves for different time periods in North America, which we discussed in Chapter 21. Compared to the period before the arrival of humans—150,000 to 11,500 years ago—the species-area curve for the period after human arrival—11,500 to 500 years ago—is significantly lower The losses include 56 species and 27 genera of large mammals, including the giant ground sloth, the saber-toothed tiger, and several species of horses, camels, elephants, and lions. Simply put, the arrival of humans coincided with a 15 to 42 percent decline in mammal diversity, When researchers created species-area curves of North American mammals from different geographic regions before and after human arrival, they discovered that from 11,500 to 500 years ago (i.e., after humans arrived), the number of mammals declined anywhere from 15 to 42 percent, depending on the geographic region examined.

In that case, the snake caused the decline or extinction of nine species of birds, three species of bats, and several species of lizards. In general, introduced species that ? with native species rarely cause ? of native species, whereas introduced species that act as predators or pathogens on native species can cause large population declines and extinctions of native species. brown tree snake introduced to the island of Guam,' -decline or extinction of nine species of birds, three species of bats, and several species of lizards competettors rarely cause extinction

compete rarely cause extinction it is estimated that invasive insects alone cause $70 billion in damage each year around the world.

Explanations for these extinctions include rapid climate change following the retreat of the glaciers, hunting pressure from the human population, and epidemic diseases carried from Asia by domesticated animals READ diversity of mammal species had been substantially reduced during the period of human occupation of North America magnitude of a mass extinction depends on how many of the species currently on Earth go extinct during the next few centuries. Threatened species are those whose populations face a high risk of extinction , considered "endangered. Near-threatened species are those that will likely become threatened in the future large percentage of them have not been studied well enough to know if a species is abundant or declining. conifers, birds, mammals, amphibians, fish, and reptiles. best biodiversity data

disease, glacier, hunting Many scientists hypothesize that most of the large mammals were driven extinct by humans who hunted them. We know that the diversity of mammal species had been substantially reduced during the period of human occupation of North America prior to the Industrial Revolution, although we can't be sure of the reason. Whether the world's current extinction rate of species will approach the magnitude of a mass extinction depends on how many of the species currently on Earth go extinct during the next few centuries. To assess how different groups of organisms are currently faring, the International Union for Conservation of Nature (IUCN) has defined categories that describe whether a species is abundant, threatened, or extinct. Threatened species are those whose populations face a high risk of extinction in the future. This category includes species that are considered "endangered. Near-threatened species are those that will likely become threatened in the future. In contrast, least-concern species are those that have abundant populations and are not likely to become threatened in the future In some cases, the status of a species has not been determined or there are simply insufficient data to make a reliable determination. status of species from a large taxonomic group is not easy. Many groups contain thousands of species, and often a large percentage of them have not been studied well enough to know if a species is abundant or declining. our best data to assess the decline in biodiversity are for conifers, birds, mammals, amphibians, fish, and reptiles.

biodiversity crisis extinct spp at record rate, possible mass extinction

don't want keystone pred around threats from growing human population

Human advances in techniques for logging trees, plowing grasslands, and capturing animals more efficiently have allowed us to harvest species at rapid rates and drive some species to extinction. F commercial hunters in North America have hunted to extinction the Steller's sea cow, great auk (Pinguinus impennis), passenger pigeon (Ectopistes migratorius), and Labrador duck Wherever humans have colonized new regions, some elements of the fauna have suffered Mediterranean region to see how human diets changed over thousands of years. early human populations initially ate large quantities of tortoises and shellfish, which were easy to catch. supplies of those foods were depleted over time, people switched to hunting hares, partridges, and other small mammals and birds. fish to mammals and birds the harvesting is part of an illegal trade endangered species of orchids, are sold for their beauty. rare trees, such as big-leaf mahogany (Swietenia macrophylla), are sold for their lumber,

during the past 3 centuries, commercial hunters in North America have hunted to extinction the Steller's sea cow (Hydrodamalis gigas), great auk (Pinguinus impennis), passenger pigeon (Ectopistes migratorius), and Labrador duck (Camptorhynchus labradorius). Each of these once-abundant species was valued for food or feathers, easily killed Wherever humans have colonized new regions, some elements of the fauna have suffered. For example, researchers examined the skeletal remains of animals in archaeological sites around the Mediterranean region to see how human diets changed over thousands of years. . At a site in current-day Italy, they found that early human populations initially ate large quantities of tortoises and shellfish, which were easy to catch. As you can see in Figure 22.13, as supplies of those foods were depleted over time, people switched to hunting hares, partridges, and other small mammals and birds. . In some cases, the harvesting is part of an illegal trade in plants and animals, an endeavor that is valued at $5 billion to $20 billion annuall For example, many animal skins are sold for furs and some cultures believe that certain animal body parts have medicinal value. Some species of rare trees, such as big-leaf mahogany (Swietenia macrophylla), are sold for their lumber, while species of rare flowers, such as endangered species of orchids, are sold for their beauty.

Species known to be in the wild in the year 1500 but that have no individuals alive today are classified as _____ species.

extinct

complete introduced spp data there are currently more than 1,600 introduced species in the Nordic region highest-profile introduced species in the United States is the silver carp (Hypophthalmichthys molitrix), a species of fish that has been introduced around the world because it consumes excess algae in ponds used by water treatment plants and aquaculture operations The primary concern was that because the Illinois River connects the Mississippi River to Lake Michigan via a shipping canal, the carp had the potential to invade the entire Great Lakes ecosystem.

f Sweden, Finland, Norway, Denmark, and Iceland. As you can see in Figure 22.16, the number of introduced species in this area has rapidly increased since 1900. Across terrestrial, freshwater, and marine ecosystems, there are currently more than 1,600 introduced species in the Nordic region Similarly, during the past 200 years in North America, thousands of species have been introduced, many of which have spread rapidly and are considered invasive species North America currently has a large number of invasive species that include nearly 200 pathogens, 300 vertebrates, 500 insects, and 1,600 plants. One of the highest-profile introduced species in the United States is the silver carp (Hypophthalmichthys molitrix), a species of fish that has been introduced around the world because it consumes excess algae in ponds used by water treatment plants and aquaculture operations carp escaped captivity in the 1980s when floodwaters washed them out of their ponds and into the Mississippi River. The primary concern was that because the Illinois River connects the Mississippi River to Lake Michigan via a shipping canal, the carp had the potential to invade the entire Great Lakes ecosystem. washed into Mississ, connects the Mississippi River to Lake Michigan , potential to invade the entire Great Lakes voracious consumer of algae that scientists worry it will compete with native consumers of algae, which serve as a key link in the food chain for many species of commercially important fish. The carp also has the unusual behavior of jumping out of the water when a boat passes by.

regulating services

flood control and disease, mitigate effects harms from changing climates, cultural recreational spiritual aesthetic values tourist income may exceed what's received from clearing forest or using land for housing or industry 2

we saw that a reduction in habitat size can lead to reduced population sizes and make it more likely a population will go extinct habitat fragmentation , significant reason that many national parks have lost species of mammals over the past 50 years fragmented habitats have a high proportion of edge habitat that can alter the abiotic conditions bronzed cowbird, an edge specialist that parasitizes the nests of other songbirds, they thrive, others do not original tallgrass prairie once covered 69 million ha across the middle of North America.->Less than 4 percent remains today. drainage for agriculture and other uses has reduced the area of wetlands by more than half. harvest species at rapid rates and drive some species to extinction.

habitat loss also leads to smaller habitat sizes and increased habitat fragmentation. This process is thought to be a significant reason that many national parks have lost species of mammals over the past 50 years, despite being protected from most harmful human activities. In addition, fragmented habitats have a high proportion of edge habitat that can alter the abiotic conditions of the interior habitat and favor edge species when we discussed the nest parasite known as the bronzed cowbird, an edge specialist that parasitizes the nests of other songbirds and leads to their decline. Forests are not the only habitats that humans have changed. According to the National Park Service, the original tallgrass prairie once covered 69 million ha across the middle of North America. Less than 4 percent remains today. Because the remaining areas are small fragments, many local populations of prairie plants and animals have gone extinct A similar story exists for wetland habitats. Scientists estimate that in the 1600s, wetlands covered more than 89 million ha in the lower 48 states, but drainage for agriculture and other uses has reduced the area of wetlands by more than half. prairie and wetland loss Human advances in techniques for logging trees, plowing grasslands, and capturing animals more efficiently have allowed us to harvest species at rapid rates and drive some species to extinction. commercial hunters in North America have hunted to extinction the Steller's sea cow (Hydrodamalis gigas), great auk (Pinguinus impennis), passenger pigeon (Ectopistes migratorius), and Labrador duck (Camptorhynchus labradorius). Each of these once-abundant species was valued for food or feathers, and they were easily killed. For example, researchers examined the skeletal remains of animals in archaeological sites around the Mediterranean region to see how human diets changed over thousands of years. At a site in current-day Italy, they found that early human populations initially ate large quantities of tortoises and shellfish, which were easy to catch as supplies of those foods were depleted over time, people switched to hunting hares, partridges, and other small mammals and birds. By examining the bones of consumed animals found in archaeological excavations, researchers have determined that early humans in Italy initially consumed animals that were easy to catch, such as tortoises and shellfish. Once these animals became rare due to overharvesting

Of the 8 gigatons of carbon that are put into the air each year by human activities, about ? gigatons are taken out of the air by producers, which reduces the effect humans have on global temperatures due to global warming.

half 8 giga of carbon

kudzu fast growing stabilize enbamknets on roadways lots of world's terr spp located in small areas, biodiversity hotspots

invasive grwogin everywhere lots of world's terr spp located in small areas, biodiversity hotspots in Medit climate, warm humid climates, coastal Cali 34 hotspots, 2.3 percent land surface containing 50 perc world plants , adn 42% animals dont't exclude consveraiton from low diversity areas like Midwest

most conservation sucess LARGE geographic areas, LOW human densities, LOVELY a positive public attitude toward the preservation effort, and effective LAW enforcement

large geographic areas, low human densities, a positive public attitude toward the preservation effort, and effective law enforcement When overharvesting is identified as a cause of decline in a species, reducing the harvest is an obvious approach to protection. However, this is complicated when it involves people's livelihoods; we saw that the collapse of the Atlantic cod fishery had a major negative economic impact on the fishing industry reducing the harvest of a declining species often leads to a return to abundanc takes long time tho

Sometimes a species comes so close to extinction that it requires human intervention to bring it back from the brink. We saw an example of this when we discussed the recovery program for the black-footed ferret California condor, a large vulture that feeds on dead animals including illegal shooting and the illegal collection of eggs from condor nest

lots of time and money A classic example of a species reintroduction is the case of the California condor, a large vulture that feeds on dead animals (Figure 22.25). During the latter half of the twentieth century, condor numbers dwindled due to a variety of causes, including illegal shooting and the illegal collection of eggs from condor nest

Only a small percentage of all species that ever lived on Earth are present today. Over the past 3.5 billion years, it is estimated that 4 billion species have existed on Earth; 99% of these species are now extinct. Scientists have hypothesized increases in human population during the past 10,000 years has initiated a sixth mass extinction event. 10 k human years, 1,000 pace increase in spp lost The United Nations Convention on Biological Diversity estimates that the extinction rate over the past 50 years is 1,000 times historic rates. If this rate continues for hundreds of years, it could qualify as a mass extinction event. 4 billion across all time right now 3 to 100 mil like 10 mil, 1.3 mil new spp names

most 4 oil now extinct 50s under two bil people , 8 bill thanksgiving 1.3 million species have received Latin names; 15,000 new species are described each year. but wstimated that 4 billion across all time Estimates for the total number of species range from 3 to 100 million; most scientists agree that there are about 10 million species Some extinctions are natural; some are caused by humans. Over the past 500 million years, the world has experienced five mass extinction events. Mass extinction events: events in which at least 75% of the existing species go extinct within a 2-million-year period. most families now

Select the statement that describes why different groups of conservationists may favor different criteria when prioritizing biodiversity hotspots. For example, the western United States typically have lower species richness but are also home to iconic species such as bears, bison, and eagles. Likewise, wetlands can have low species richness but still serve vital ecological functions A region's biodiversity is only one criterion used by conservationists. Some regions are important to preserve even though they have relatively few species. Likewise, wetlands can have low species richness but still serve vital ecological functions such as flood control and water filtration

not Areas with large numbers of animal species usually have low human population densities. Many regions with high human population densities also have large numbers of species. A region's biodiversity is only one criterion used by conservationists. Some regions are important to preserve even though they have relatively few species. Areas with low species richness can still have high conservation value. Some conservationists prioritize protecting areas with higher measures of species richness. However, some areas of great conservation value can also have lower measures of species richness. For example, the western United States typically have lower species richness but are also home to iconic species such as bears, bison, and eagles. Likewise, wetlands can have low species richness but still serve vital ecological functions such as flood control and water filtration Species richness is one important factor that determines biodiversity. Regions with more plant species tend to have more animal species too. Thus, some conservationists take the number of plant species into account when deciding which regions to protect. Both terrestrial and marine ecosystems have ecologic value. Conservationists find it important to protect both of these types of ecosystems. Many locations with high species diversity also contain large human populations. Human activities cause species declines. Conservationists consider these threats when making management decisions

First mass extinction (443 Mya): most species lived in the oceans; an ice age caused sea levels to drop and ocean chemistry to change. Second mass extinction (359 Mya): much of the ocean lacked oxygen; reasons for this phenomenon are unclear. Third mass extinction (248 Mya): causes are uncertain; 96% of all species went extinct. Fourth mass extinction (200 Mya): hypotheses for this extinction include volcanic activity, asteroid collisions, and climate change. Fifth mass extinction (65 Mya): volcanic eruptions generated cold weather, followed by an asteroid impact in the Yucatan Peninsula. Dust from the asteroid impact blocked the sun's rays, making Earth much less hospitable to dinosaurs and many other groups.

ocean too saline during ice age ntense glacial and interglacial periods created large swings in sea levels and moved shorelines dramatically second dont know why ocean lacked oxygen fifth dinosaur 65mya volcano cold weather and yucca asteroid, kicked up more dust, so even less sun coming through

pollution Biomagnification : concentration of a contaminant increases as it moves up the food chain. DDT control crops pests and mosquitoes entered water, it bound to algae and became 10x more concentrated on algae eat algae, 276,000x more concentrated in fish-eating birds than it was in the water declines in many predatory birds

pollution Pollutants can take many forms. Biomagnification: the process by which the concentration of a contaminant increases as it moves up the food chain. Example: The pesticide DDT was used to control crops pests and mosquitoes; when DDT entered water, it bound to algae and became 10x more concentrated on algae than it was in water. Through predation, DDT ultimately became 276,000x more concentrated in fish-eating birds than it was in the water. This led to declines in many predatory birds; the United States banned the use of DDT in 1972.

Introduced species often prey upon native species or compete with them for resources. Introduced ? drive declines in native species more often than introduced ? do. However, ? predators and competitors can drive native species extinct. Introduced species often PREY upon native species or COMPETE competitors both drive native spp extinct MORE , than introduced competitors dbut both can reducing food for native=food options become limited, a species' niche narrows It is much less likely that an introduced predator could drive a large metapopulation to extinction. Those native species that live in small populations in isolated habitat patches are the most likely to be driven to extinction by an introduced predator

predators, competitors both drive native spp extinct An introduced competitor can drive a native species to extinction by limiting its food choices. When food options become limited, a species' niche narrows. If another event or species reduces the remaining food options, the native species may die for lack of food. Having fewer food choices would not increase the incidence of foodborne illness. Fewer food choices would also be unlikely to generate rapid population growth. Native species living in small, isolated populations are highly vulnerable to introduced predators. The isolated population often cannot emigrate away from predators, nor receive many immigrants. A new predator could potentially consume all individuals in a small population. It is much less likely that an introduced predator could drive a large population to extinction. In a metapopulation, smaller subpopulations might survive predation due to immigration from other patches. Introduced competitors usually only compete for some of the resources that native species use. Sometimes native species can survive if they are able to subsist on alternative food sources or adjust to living in less favorable habitats. When it comes to food, a reduction in primary food options can be dangerous for native species. Reducing the variety of food choices for the natives can cause their extinction by making the niche of the native species narrower. Some introduced predators may be a greater threat to the native species than competitors. Introduced predators may be more aggressive or have different hunting methods than native species. Native species may not have defenses against the new hunting techniques. Those native species that live in small populations in isolated habitat patches are the most likely to be driven to extinction by an introduced predator

What effects do regulations on harvesting at‑risk fish species have on marine fisheries? Harvesting resources at responsible levels can lead to long‑lasting ecological and economic productivity. overharvesting can cause extinctions and the collapse of important resources. To prevent fishery collapse, government policies regulate the amount of fish that fishers can remove from ocean habitats. regulate the amount of fish that fishers can remove from ocean habitats.

reduced job opportunities for fishers fewer collapses in ocean fisheries Throughout history, humans have harvested plant and animal species from their environments. Harvesting resources at responsible levels can lead to long‑lasting ecological and economic productivity. However, overharvesting can cause extinctions and the collapse of important resources. Ocean fisheries that contain commercially important species of fish and shellfish provide food for many communities. Healthy fisheries also provide jobs for people in the fishing industry. Modern fishing technologies allow fishers to efficiently remove a great number of fish from their ocean habitats. Whereas high rates of fishing provide food and economic opportunities, overharvesting also causes rapid declines in fish population sizes. When a commercially important fish species reaches critically low numbers, the fishery collapses. Fish become so scarce that fishers cannot find fish to harvest from the habitat. To prevent fishery collapse, government policies regulate the amount of fish that fishers can remove from ocean habitats. These policies aim to prevent collapse by ensuring that a healthy number of fish remain in the population. However, these policies also threaten the livelihoods of fishers who work in the industry. Limitations on the amount of fish that can be harvested reduce job opportunities for fishers. Thus, government agencies that regulate harvesting must consider both the ecological and economic impacts of their recommendations.

DONT READ increased richness at islands round equator and close to land Pacific island chains highest diversity including Great Barrier Reef num spp in area=equilb bw specitaion and extinction spp continullayi created over time bc tropical areas have no glaciation events, no disruption in species, theory for highest diversity? more energy at equator greater enviro heterogeneity PET=potental amt water could be evap from soil and evapotrans from plants given avg temp and humidity? gives index energy intro enviro index of energy given by PET and correlate w richness but plateau as temp increases temperate marine less stable temp nutrient conditions and lower producitvity tropical enviro stable temp nutrient regimes, 2010 only significant predictor of marine productivity is MEAN temperature of sea surface and being near land,

reptiles warmer areas SE for amphibians, see trees even when too cold, highest diversity closest to land masses in marine areas, increased richness at islands round equator and close to land Pacific island chains highest diversity including Great Barrier Reef spp continullayi created over time bc tropical areas have no glaciation events and more time to accumulate species, also not cold num spp in area=equilb bw specitaion and extinction variation in richness across latitude should reflect equilib as well more energy at equator more spp where greater enviro heterogeneity desert less productive than marsh, but Sahara just dust even lower richness num spp at location correlated to rain and solar energy PET=potental amt water could be evap from soil and evapotrans from plants given avg temp and humidity? gives index energy intro enviro correlate w richness but plateau as temp increase becomes a stressor, or humidity way high humid sights not breaking 100 degrees as much? energy support more richness and abundance, energy diversity hypo for sites temp driven by latitudes? not why more biodiversity at tropics not driven by productivity productivity driven by higher temperature at higher latitudes? tropical enviro stable temp nutrient regimes, temperate marine less stable temp nutrient conditions and lower producitvity 2010 only significant predictor marine productivity is mean temperature of sea surface and being near land, doesn't matter if warm ocean but not near land, not nutrient inputs regenerated near surface where prim prod takes place

Individuals take 6 to 8 years to reach maturity and in the wild typically lay only one egg per year. they removed the single egg, a female would lay another from 1 to 3 eggs/year resulted in the preservation of large tracts of habitat in mountainous regions of southern California restoring the condor population can be compatible with other land uses.

researchers discovered that if they removed the single egg, a female would lay another. In fact, a female condor could be tricked into laying up to three eggs per year. high-profile case heightened local residents' awareness of conservation issues and resulted in the preservation of large tracts of habitat in mountainous regions of southern California. People have also come to understand that restoring the condor population can be compatible with other land uses.

biodiversity concepts comes from us SEE constructs

social, economic, ecological construct extinction natural but higher rate than we've seen before conservation can reverse or slow biodiversity declines done correctly

Select the strategies that may slow the sixth mass extinction. Ecologists predict that current species declines could result in a sixth mass extinction. Habitat loss contributes most toward population declines. Conservationists aim to preserve intact regions of habitat so that species can thrive. For example, reintroduced wolves in Yellowstone National Park reduced the elk population. The decline in elk allowed some species of plants to recover.

species reintroductions habitat protection Our planet has experienced five mass extinction events. In recent history, human activities have accelerated the loss of biodiversity. Ecologists predict that current species declines could result in a sixth mass extinction. Conservationists recommend several strategies to reduce declines in biodiversity. Species need suitable areas of habitat in which to live and reproduce. Habitat loss contributes most toward population declines. One way to prevent extinction is to protect the habitats where species live. Landscape fragmentation reduces the total amount of habitat, which reduces biodiversity. Conservationists aim to preserve intact regions of habitat so that species can thrive. Overharvesting can cause declines in species, even if the habitat remains intact. As a result, conservationists recommend reduced harvesting to protect species in decline. For example, wildlife managers restrict the amount of shellfish that fishers can catch in certain waters. Conservationists can bring in new individuals to restore declining species in a region. The reintroduced species may affect other members of the community. For example, reintroduced wolves in Yellowstone National Park reduced the elk population. The decline in elk allowed some species of plants to recover.

For a school project, you decide to visit a local state park to assess its instrumental value. After paying the entrance fee, you meet with a park guide, who gives you a tour of the land. First, she shows you a large forest of conifer trees and tells you that this section of the forest is used for sustainable logging. Next, she leads you to a large marsh that helps prevent flooding in the area and also helps purify the water before it moves downstream. This marsh provides the state's only habitat for three endangered bird species. Based on your visit, which instrumental values would you report that the park provides?

sustainable logging,=provisionin service marsh that helps prevent flooding in the area and also helps purify the water=regulating service state's only habitat for three endangered bird species=suppporting provisioning, regulating, cultural, and supporting

Greater Yellowstone Ecosystem seeks to maintain the region in a natural, self-sustaining condition. Natural forest fires should be allowed to burn, top predators are natural controls over populations of large grazers, wolves , bears

top predators, such as the grizzly bear and gray wolf, should be restored. these top predators are natural controls over populations of large grazers, with far-reaching effects on the ecosystem. Yellowstone National Park and the many different types of land surrounding it are collectively managed as one large ecosystem.

Biotic homogenization The process by which unique species compositions originally found in different regions slowly become more similar due to the movement of people, cargo, and species. kill insects and other invertebrate animals, insecticides=one Pesticide herbicides that kill plants fungicides that kill fungi unique species compositions originally found in different regions slowly have become more similar due t

we discussed acid precipitation, and in Chapter 20, we looked at the effects of adding excess nutrients to bodies of water. Both examples demonstrate the harmful effects of pollutants on biodiversity. Pesticides are a common type of pollutant. They include insecticides that kill insects and other invertebrate animals, herbicides that kill plants, and fungicides that kill fungi. These chemicals are designed to target a particular type of pest; ideally, they will not harm nonpests in the ecosystem.

As we discussed in Chapter 6, causes of decline in genetic diversity include declining population sizes, inbreeding depression, and the bottleneck effec These declines in genetic diversity reduce the probability that a population contains genotypes able to survive changing environmental conditions, changes in climate and emerging infectious diseases. decline in the genetic diversity of livestock and crops livestock for labor and transportation include just seven species of mammals (cattle, pigs, sheep, goats, buffalo, horses, and donkeys) and four species of birds (chickens, turkeys, ducks, and geese) varieties have not been maintained because larger, modern livestock operations favor those few breeds that are the most productive Europe, for instance, about half of the livestock breeds present in 1900 are now extinct 43 percent are at a serious risk of extinction less diversity to draw from should we need to breed domesticated animals that can live in new locations or in changing environment or new disease

we have also seen a decline in the genetic diversity of many species. Smaller populations do not possess the same amount of genetic diversity as large populations. These declines in genetic diversity reduce the probability that a population contains genotypes able to survive changing environmental conditions, lack more resistant genotypes including changes in climate and emerging infectious diseases. The decline in the genetic diversity of livestock and crops has a direct and immediate effect on humans. T The primary livestock that we consume or use for labor and transportation include just seven species of mammals (cattle, pigs, sheep, goats, buffalo, horses, and donkeys) and four species of birds (chickens, turkeys, ducks, and geese) bred these species for a wide variety of different traits, including size, strength, quality of meat, and ability to persist under challenging environmental conditions such as drought and diseases During the past century, many livestock varieties have not been maintained because larger, modern livestock operations favor those few breeds that are the most productive in terms of meat or milk. In Europe, for instance, about half of the livestock breeds present in 1900 are now extinct. Of those breeds remaining, 43 percent are at a serious risk of extinction. In North America, 80 percent of the livestock breeds that have been evaluated are either declining in abundance or facing extinction Such a rapid decline in genetic diversity means there is considerably less diversity to draw from should we need to breed domesticated animals that can live in new locations or in changing environments, or that can withstand new diseases drawing from 7,000 breeds of 35 domesticated species of birds and mammals, many , 21 percent are at risk of extinction.