Exam 4: Chapter 56- Conservation Biology and Global Change

biodiversity hot spot

-A biodiversity hot spot is a relatively small area with numerous endemic species (found nowhere else in the world) and many endangered and threatened species

effective population size

-A meaningful estimate of MVP requires determining the effective population size, which is based on the population's breeding potential -The effective population size is always some fraction of the total population size

movement corridor

-A movement corridor is a narrow strip or series of small clumps of habitat connecting otherwise isolated patches -Promote dispersal and reduce inbreeding -In areas of heavy human use, artificial corridors are sometimes constructed

greenhouse effect

- CO2, water vapor, and other greenhouse gases reflect infrared radiation back toward Earth; this is the greenhouse effect -This effect is important for keeping Earth's surface at a habitable temperature -Increasing concentration of greenhouse gases has caused the average global temperature to increase by 0.9°C since 1900 -An additional rise of at least 3°C is predicted by the end of the century

Biodiversity hot spots are good choices for nature reserves, but this approach has challenges

-An area that is a hot spot for one taxonomic group may not be for another -Designation of hot spots is often biased toward saving vertebrates and plants -Focus on hot spots puts a lot of emphasis on protecting a small fraction of the Earth's surface -The environmental conditions that favor a particular hot spot community may change over time

Ozone depletion causes DNA damage in plants and phytoplankton; increases in rates of skin cancer and cataracts are expected in humans

-An international agreement signed in 1987 has resulted in a decrease in ozone depletion -Chlorine molecules already in the atmosphere will continue to influence ozone levels for at least 50 years

Destruction of atmospheric ozone results mainly from chlorofluorocarbons (CFCs) produced by human activity

-CFCs contain chlorine, which reacts with ozone to make O2 -This decreases the amount of ozone in the atmosphere

Climate Has Effects at All Levels of Biological Organization: Effects on Populations

-Climate change has caused changes in population size and timing of growth, reproduction, and migration -Some populations experience food shortages and reduction in survival and reproductive success

Biological Effects of Climate Change

-Climate change has reduced geographic ranges and caused population declines in hundreds of species >The geographic distributions of 67 bumblebee species have decreased in size -Organisms that cannot disperse rapidly or find suitable habitat are less likely to survive rapid climate change

Weighing Conflicting Demands

-Conserving species often requires resolving conflicts between habitat needs of endangered species and human demands -Because not all species can be saved, the ecological role of a species and its importance for conserving biodiversity must be considered

Critical load

-Critical load is the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity -Nutrients that exceed the critical load leach into groundwater or run off into aquatic ecosystems -Agricultural runoff and sewage lead to phytoplankton blooms -When the phytoplankton die, their decomposition depletes oxygen and causes "dead zones

Ecosystem services

-Ecosystem services encompass all the processes through which natural ecosystems and their species help sustain human life -Some examples of ecosystem services include: >Purification of air and water >Detoxification and decomposition of wastes >Crop pollination, pest control, and soil preservation >Moderation of weather extremes

Genetic Diversity

-Genetic diversity comprises genetic variation within a population and between populations -The extinction of a population reduces the genetic diversity required for microevolution within a species

Global Change

-Global change includes alterations in climate, atmospheric chemistry, and broad ecological systems that reduce the capacity of Earth to support life -Acid precipitation (pH < 5.2) was one of the first types of global change to cause concern -Acid precipitation contains sulfuric acid and nitric acid from the burning of wood and fossil fuels -Air pollution from one region can result in acid precipitation downwind -Acid precipitation kills fish and other lake-dwelling organisms -Environmental regulations have helped to decrease acid precipitation

Finding Solutions to Address Climate Change

-Global warming can be slowed by reducing energy use and converting to renewable sources of energy -Stabilizing CO2 emissions is an international effort -Reduced deforestation would also decrease greenhouse gas emissions

Alarming statistics regarding extinction and biodiversity

-Globally,12% of birds and 21% of mammals are threatened -Extinction may occur at the local population level, or species may be lost at a global scale

Establishing Protected Areas

-Governments have set aside about 7% of the world's land in various forms of reserves -Placement and design of reserves pose many challenges >Should the reserve be managed to protect threatened species or left in its natural state?

Ecosystem Diversity

-Human activity is reducing ecosystem diversity, the variety of ecosystems in the biosphere >More than half of the wetlands in the contiguous United States have been drained and converted to other ecosystems

Nutrient Enrichment

-Human activity often removes nutrients from one part of the biosphere and adds them to another -Harvest of agricultural crops exports nutrients from the agricultural ecosystem -Agriculture leads to depletion of nutrients in the soil -Fertilizers add nitrogen and other nutrients to the agricultural ecosystem

Habitat Loss

-Human alteration of habitat is the greatest threat to biodiversity throughout the biosphere -Habitat loss and fragmentation occur over immense regions -Habitat fragmentation often leads to species loss because the smaller populations in habitat fragments are more vulnerable to extinction -Habitat loss is also a major threat to marine and freshwater aquatic biodiversity

Toxins in the Environment

-Humans release many toxic chemicals, including synthetics previously unknown to nature -In some cases, harmful substances persist for long periods in an ecosystem -Toxic substances can accumulate in the tissues of organisms and become more concentrated in the organisms that eat them -Biological magnification concentrates toxins at higher trophic levels, where biomass is lower

Introduced Species

-Introduced species are those that humans move from native locations to new geographic regions, either intentionally or by accident -Without their native predators, parasites, and pathogens, introduced species may spread rapidly -Introduced species that gain a foothold in a new habitat may disrupt the community by preying on or outcompeting native organisms for resources >The brown tree snake, accidentally introduced to the island of Guam, preyed upon and led to the extinction of several native bird and lizard species -Humans deliberately introduced some species with good intentions but disastrous effects

Depletion of Atmospheric Ozone

-Life on Earth is protected from damaging effects of UV radiation by a protective layer of ozone molecules in the atmosphere -Satellite studies show the ozone layer over Antarctica has thinned substantially since mid-1970s -The thinning of the ozone layer is most apparent over Antarctica in the spring -Ozone levels have decreased 2-10% at mid-latitudes during the past 20 years

Northern coniferous forests and tundra show the strongest effects of global warming

-Melting snow and ice uncover darker, absorptive surfaces that reflect less radiation into the atmosphere -Some Artic regions have switched from being CO2 sinks to CO2 sources

Minimum viable population (MVP)

-Minimum viable population (MVP) is the minimum population size at which a species can survive -MVP depends on factors that affect a population's chances for survival over a particular time

Nature reserves

-Nature reserves are biodiversity islands in a sea of habitat altered or degraded by human activity -Nature reserves must consider disturbances as a functional component of all ecosystems -An important question is whether to create fewer large reserves or more numerous small reserves -Large reserves can support large, far-ranging animals with low-density populations or species that are sensitive to habitat edges -Small, unconnected reserves may slow the spread of disease between populations

Overharvesting

-Overharvesting is human harvesting of organisms at rates exceeding the ability of their populations to rebound -Species with restricted habitats and large organisms with low reproductive rates are especially vulnerable to overharvesting >African elephant populations declined as a result of overhunting to support the ivory trade

Species Diversity

-Species diversity is the variety of species in an ecosystem or throughout the biosphere -According to the U.S. Endangered Species Act: >An endangered species is one that is in danger of extinction throughout all or much of its range >A threatened species is likely to become endangered in the foreseeable future

Benefits of Species and Genetic Diversity

-Species related to agricultural crops can have important genetic qualities >Plant breeders bred virus-resistant commercial rice by crossing it with a wild population -In the United States, 25% of prescriptions contain substances originally derived from plants Rosy periwinkle contains alkaloids that inhibit cancer growth

Sustainable development

-Sustainable development is development that meets the needs of people today without limiting the ability of future generations to meet their needs -It requires connections between life sciences, social sciences, economics, and humanities -The goal of the Sustainable Biosphere Initiative is to define and acquire basic ecological information for responsible development, management, and conservation of Earth's resources

Fragmentation and Edges

-The boundaries, or edges, between ecosystems are defining features of landscapes -An edge has its own set of physical conditions, which differ from those on either side of it -Some species take advantage of edge communities to access resources from both adjacent areas -Species adapted to forest interiors show the greatest decline in small habitat patches -Landscapes dominated by small fragments are likely to support fewer species

Declining-Population Approach

-The declining-population approach focuses on threatened and endangered populations that show a downward trend, regardless of population size -It emphasizes the environmental factors that cause a population to decline -Requires careful evaluation of the causes of decline -The natural history of the species is studied and used to develop and test hypotheses of possible causes of decline

Urban Ecology

-The field of urban ecology examines organisms and their environment in urban settings -A critical area of research centers on urban streams, which experience rapid water fluctuations after rainfall

Landscape Structure and Biodiversity

-The physical features, or structure, of a landscape can strongly influence biodiversity -Many species use more than one kind of ecosystem or live on the borders between ecosystems

Small-Population Approach

-The small-population approach studies processes that cause extinctions once population sizes have been greatly reduced -A small population is prone to inbreeding and genetic drift, which draw it down an extinction vortex -The key factor driving the extinction vortex is loss of the genetic variation necessary to enable evolutionary responses to environmental change

Zoned reserves

-Zoned reserves include relatively undisturbed areas surrounded by areas where human activities are unlikely to harm the protected area -The modified areas surrounding the protected areas serve as buffer zones -Costa Rica has become a world leader in establishing zoned reserves

Conservation biology

-seeks to conserve biological diversity at all levels, integrates several fields: >Ecology >Physiology >Molecular biology >Genetics >Evolutionary biology

Biodiversity has three main components

1. Genetic diversity 2. Species diversity 3. Ecosystem diversity

Biologists focusing on conservation at the population and species levels follow two main approaches

1. The small-population approach 2. The declining-population approach

Most species loss can be traced to four major threats:

1.Habitat loss 2. Introduced species 3. Overharvesting 4. Global change

Human-caused changes in the environment include

1.Nutrient enrichment 2.Accumulation of toxins 3.Climate change 4.Ozone depletion

DNA analysis helps conservation biologists identify the source of illegally obtained animal products

DNA from illegally harvested ivory can be used to trace the original population of elephants to within a few hundred kilometers

Climate Has Effects at All Levels of Biological Organization: Effects on Individual Organisms

Global warming has increased the risk of overheating in some species, leading to reduced food intake and reproductive failure

Climate Has Effects at All Levels of Biological Organization: Effects on Cells

Increasing temperature affects rates of enzymatic reactions and impairs cellular defense responses

Pharmaceutical drugs enter freshwater ecosystems through human sewage and agricultural runoff

Sex steroids, such as the estrogen used in birth control pills, can shift the sex ratio toward females in some species of fish

Toxins that cannot be degraded by microorganisms persist in the environment for years

Some harmless chemicals can interact with abiotic and biotic factors in the environment to become more toxic

Climate Has Effects at All Levels of Biological Organization: Effects on Communities and Ecosystems

Species migration in response to climate change has caused dramatic change in ecological communities

The loss of species also means loss of unique genes and genetic diversity

The enormous genetic diversity of organisms has potential for great human benefit

Greenhouse Gases and Climate Change

The release of gaseous waste products into the atmosphere through human activities is driving climate change

Conservation efforts have historically focused on saving individual species

Today, the emphasis is on sustaining the biodiversity of entire communities, ecosystems, and landscapes

MVP is often used in population viability analysis

Viability analysis is used to predict a population's chances for survival over a particular time interval