APES Final Chapters 4, 5 and 6
population change calculation
(births+immigration) - (deaths+emigration) when births+immigration exceeds death+emigration, a population grows and vice versa
mutations that get passed on
(can occur in any cell) but only mutations that take place in genes of reproductive cells are passed on to offspring; can result in a new genetic trait (called a heritable trait) which can be passed from one generation to the next-- causes populations to develop differences among individuals (ex. genetic variability)
stages of demographic transition
- preindustrial: population rate grows slowly because of a high birth rate (to make up for high infant mortality) and a high death rate - transitional: population grows rapidly because birth rates are high and death rates drop because of improved food production & health - industrial: population growth slows as both birth and death rates drop because of improved food production, health, & education - postindustrial: population growth levels off and then declines as birth rates equal and then fall below death rates
advantages of living in clumps
- resources a species needs vary greatly in availability from place to place, so species tend to cluster where the resources are available - individuals moving together have better chances of encountering clumps of resources than they would searching on their own - living in groups provides some protection from predators - living in packs gives some predator species a better chance of getting a meal
when environmental conditions change dramatically...
a population of species can adapt (through natural selection) migrate (if possible), or become extinct
age structure
a population's distribution of individuals among various age groups; can have a strong effect on how rapidly it grows or declines
do rain forests have a low or high species evenness?
because rain forests are so diverse, they contain around the same amount of individuals from each of many different species. this makes them have a high species evenness.
why biodiversity is important
incredibly important part of the natural capital that helps keep us alive and support our economies; with help of technology, we use biodiversity to provide us with food, wood, fibers, etc.; provides ecosystem services that preserve quality of the air & water, maintain fertility of topsoil, decompose/recycle wastes, control populations of species considered as pests; increase stability of ecosystems & resistance to of ecosystems to harmful invasive species
2 aspects of stability/ sustainability in living systems
inertia (also known as persistence)- the ability of a living system to survive moderate disturbances resilience- the ability of a living terrestrial system to be restored through secondary ecological succession after a more severe disturbance
5 basic types of interaction between species
interspecific competition, predation, parasitism, mutualism, and commensalism
most common interaction
interspecific competition- when members of two or more species use the same limited resources (ex. food, water, light, space); involves the ability of one species to become more efficient than another species in obtaining the resources it needs
factors in reducing the # of births & abortions worldwide
planned parenthood, providing educational & clinical services that help couples choose how many children to have and when to have them
what a J-shaped growth curve represents
plotting the number of individuals against time- a population w/ few limitations on its resource supplies can grow exponentially at a fixed rate or percentage each year (starts slowly but then accelerates as the population and its base size increases
case study: sea otters
sea otters costume 20-35% of their weight in sea urchins, abalone, other shellfish. by early 1900s, they were hunted to near extinction (used to have population of 13,000-20,000 in CA's waters) for their fur and b/c fishers viewed them as competitors for shellfish. since then, their pop has grown from 50 (1938) to 2,800 (2012); declared endangered in 1977 by US Fish&Wildlife Service. we should care about the otters because of ethical reasons, they help generate $$ in tourism venues, and because they are classified as a keystone species (without the otters, sea urchin populations would go out of control and destroy the kelp forests-otters live in them- and much of the biodiversity they support)
genetic resistance
the ability of one or more organisms in a population to tolerate a chemical designed to kill it-- such resistance develops fairly quickly in populations of organisms that produce large numbers of offspring (ex. bacteria and insects)
crude birth rate
the number of births per 1,000 people in a population per year (same goes for crude death rate, just switch number of births to deaths)
species richness
the number of different species in an area-- how rich or plentiful it is in species
limiting factor principle
too much or too little of any physical or chemical factor can limit or prevent the growth of a population, even if all other factors are at or near the ideal range of tolerance
mutualism
two species behave in ways that benefit both by providing each w/ food, shelter, or some other resource (ex. clownfish that live in sea anemones, anemones provide shelter for this fish while the fish feed on the waste matter from the anemone's meals that could turn into parasites)
case study: population 7 billion
7.1 billion ppl on earth in 2011- 3 times as many as in 1950. as our population grows & as we use more of the earth's natural resources, our ecological footprints expand and degrade the natural capital that keeps us alive. 3 major factors accounted for the rapid rise of human population: emergence of modern agriculture allowed us to feed more people with each passing century; developed technologies that have helped us to expand into almost all of the planet's climate zones & habitats; death rates have dropped sharply because of improved sanitation and health care.
population growth in 2012
84 million people added to the population- more than 230,000 people each day, 3 people every second (2% added to world's more-developed countries, other 98% added to middle- and low-income/ less-developed countries) **population grows more in less-developed countries
how death from AIDs can disrupt country's social/economic structure
AIDs kills a large portion of young adults, which leaves many children orphaned and usually with the disease. it also causes a sharp drop in life expectancy and the loss of productive young-adult workers
natural selection
Charles Darwin & Alfred R. Wallace observed that individual organisms must struggle constantly to survive by getting enough food/water/resources, to avoid being eaten, and to reproduce; individuals w/ a specific advantage (known as a trait) over other individuals of that population are more likely to survive & produce offspring that have that same specific advantage-- these survival traits would become more frequent in future populations of the species as individuals with those traits became more numerous&pass those traits to their offspring
generalist vs specialist species
Generalist species have broad niches (can live in many different places, eat a variety of foods, tolerate wide range of environmental conditions)- they're a lot more 'general' (ex. humans, mice, white-tailed deer) Specialist species occupy narrow niches (may be able to live in only one type of habitat, use just one/ a few types of food, tolerate narrow range of climatic/ environmental conditions)- more prone to extinction when environmental conditions change (like endemic species!!) (ex. c-h-i-n-a-'s giant panda is highly endangered because of its low birth rate, habitat loss, & specialized diet consisting mostly of bamboo)
demographic transition
as countries become industrialized and economically developed, their populations tend to grow more slowly
"The more species you have, the more likely you're going to have an insurance policy for the whole ecosystem." -O. Wilson
a complex and more diverse ecosystem has more ways to respond to most environmental disturbances/ stresses because it "does not have all its eggs in one basket"
species
a group of organisms with a set of characteristics that distinguish it from other groups of organisms; individuals must be able to produce fertile offspring; 8-10million estimated species
"fitness"/ survival of the fittest
a measure of reproductive success, not strength-- the fittest individuals are those that leave the most descendants
mass extinction rate
a significant rise in extinction rates above the background level; about 25-95% of all species wiped out --provides opportunity for the evolution of new species that can fill unoccupied ecological roles or newly created ones. evidence shows that each mass extinction has been followed by an increase in species diversity over several million years as new species have arisen to occupy new habitats or to exploit newly available resources **the balance between the formation of new species (speciation) & extinction of existing species determines the earth's biodiversity- once again, nature's way of keeping things in sync and able to keep up/ ahead of extinction.
theory of evolution
all species evolved from earlier, ancestral species- life comes from life
why aren't humans able to adapt themselves to environmental conditions?
because we are a species that is unable to produce large numbers of offspring rapidly, it takes a much longer time to adapt through natural selection (it's kind of like oil as an exhaustible resource: taking a while for humans to reproduce throws off the time scale that bacteria have and doesn't give us enough time to figure out what we need to adapt to, because by the time we do we're either dead or something else has changed in the environment.. i hope that made sense, if it didn't then ignore it)
biological evolution by natural selection
changes in a population's genetic makeup through successive generations **populations -not individuals- evolve by becoming genetically different**
world's 3 most populated countries
china (1 of every 3 persons lived there in 2012), india, US
problems associated with rapid population decline
declining work force, fewer children/grandchildren to care for the elderly, limited funds in supporting continued economic development
how nature has controlled human population
diseases, epidemics
ecosystem diversity
earth's variety of deserts, forests, mountains, oceans, lakes, rivers, and wetlands- each is a storehouse of genetic and species diversity
3 most effective ways to slow/stop population growth
elevate status of women, encourage family planning, & reduce poverty (through economic development & universal primary education)
prey species
evolved many ways to avoid and protect themselves form predators (ex. protective shells, thick bark, spines, thorns, ability to run fast)
what an S-shaped growth curve represents
exponential growth is eventually converted to logistic growth (the growth rate decreases as the population becomes larger & faces environmental resistance). over time, population size stabilizes at/near the carrying capacity of its environment, which results in S-shaped population growth curve
factors that affect how & at what rate succession occurs
facilitation- when one set of species makes an area more suitable for another species w/ different niche requirements and less suitable for itself inhibition- some species hinder the establishment and growth of other species (pine tree needles dropping and making the soil in that spot too acidic for other plants to grow there) tolerance- in which plants in the late stages of succession succeed because they are not in direct competition w/ other plants for key resources
predation in herbivores vs carnivores
herbivores can simply walk, swim, or fly to the plants they eat on. carnivores feeding on animals have two main options: pursuit and ambush (ex. cheetas run fast to catch their prey, bald eagles can fly and have keen eyesight)
adaptive trait (also know as adaptation)
heritable trait that improves the ability of an individual organism to survive and reproduce at a higher rate than other individuals in a population (this is basically Natural Selection summed up)
the significance of amphibians/ case study
historically, amphibians have been able to adjust & survive environmental changes effectively. however, human activities(such as use of pesticides that become water pollutants) are causing them to have more difficulty adapting to rapid changes- about 33% of all amphibian species are threatened w/ extinction &more than 40% of they known species is declining they're an indicator species because the decline of an amphibian population can indicate the presence of parasites, disease-causing microbes, air/water pollution, habitat loss, UV radiation, and climate change. amphibians are also important b/c if they go extinct, they can affect the extinction of other species that feed on them or they larvae (like keystone species). they also have caused many discoveries in pharmaceutical products (such as painkillers)
keystone species & why they are important
keystone species are species whose roles have a large effect on the types and abundance of other species in an ecosystem; even though they usually exist in limited numbers (which makes them more vulnerable to extinction), they they have huge effects when it comes to sustaining the ecosystem the loss of a keystone species can lead to population crashes & extinctions of other species in a community that depends on them for certain ecosystem services- w/o this species, the ecosystem will basically break out in WWIII.. so yeah, we should protect them (@c-h-i-n-a)
biomes
large regions (forests, deserts, grasslands) with distinct climates and certain species (especially vegetation) adapted to them
2 way that the movement of tectonic plates can affect evolution/ distribution of life
locations of continents & oceanic basins have influenced earth's climate, which determines where plants/animals live the movement of continents has allowed species to move, adapt to new environments, and form new species through natural selection
reproductive isolation
long-term separation of species who are unable to reproduce with each other; mutation and change by natural selection operate independently in the gene pools of geographically isolated populations
biotic potential
maximum rate at which the population of a species can increase when there are no limitations on its rate of growth
fertility rate
measure of how many children are born over a set period of time
niche vs habitat
niche is the role that a species plays in its ecosystem; a way of life in a community and includes everything that affects its survival and reproduction- basically its pattern of living habitat is just a place where it lives
species diversity
number and variety of the species present in any biological community; most obvious component of biodiversity **the more diverse an ecosystem is, the more productive it will be
geographic isolation
occurs when groups of the same population of a species get physically separated from one another for a long period of time
commensalism
one species benefits while the other one is neither harmed nor benefited (ex. plants called epiphytes which attach themselves to the trunks/branches of trees, benefit by having a solid base on which to grow and better access to sunlight)
how humans are affecting the mass extinction rate
our ecological footprints spreading across the planet in ways such as increasing the loss, fragmentation, and degradation of habitats (ex. cultivating more land to grow crops and clearing more forestland for farming, ranching, and settlement)
resource partitioning
over a period of time long enough for natural selection to happen, populations develop ways in which to minimize the amount interaction or competition w/ other species for resources. resource partitioning is when species evolve to use different parts of the scarce resource they all need by either using parts of them, using them at different times, or using them in different ways.
what happens when niches overlap
overlapping niches occur when two species compete with one another for the same resources. the greater the overlap, the more intense their competition for key resources is. If one species can take over the largest share of one or more key resources, each of the other competing species must move to another area (migrate), adapt by shifting its feeding habits or behavior through natural selection to reduce/alter its niche, suffer a sharp population decline, or become extinct in that area
terrestrial limiting factors
precipitation- low levels in desert ecosystems limit desert plant growth too much water or fertilizer can kill plants
chemical warfare
prey species discourage predators with chemicals that are poisonous (oleander plants), irritating (bombardier beetles) , foul smelling (skunks), bad tasting (monarch butterflies), clouds of blank ink emitted (species of squid & octopus)
primary vs secondary ecological succession
primary- the gradual establishment of communities containing different species in lifeless areas where there is no soil-terrestrial ecosystem- or bottom sediment-aquatic system- (abandoned highway, newly cooled lava) secondary- series of communities/ ecosystems develop in places containing soil or bottom sediment (begins in an area where an ecosystem has been disturbed, removed, or destroyed, but some soil/sediment remains- abandoned farmland, burned or cut forests) **both examples of natural ecological restoration
species richness in rain forests vs tree farms
rain forests have a greater species richness because there are so many more organisms and species than in tree farms (which are usually just planted with one species & hosts just a few others that migrate in)
inertia & resilience in rain forests and grasslands
rain forests have a high species richness & high inertia, thus are resistant to significant change/damage. but once a large part of it is cleared/severely damaged, the resilience of the resulting ecosystem may be so low that it reaches an ecological tipping point, after which it may not be able to be restored by secondary succession. because grasslands are much less diverse than forests, they have low inertia and can burn easily. however, since their plant matter is stored in underground roots, these ecosystems have high resilience & can recover quickly from fires (their root systems are able to produce new grasses)
mutation
random changes that occur when DNA molecules are copied each time a cell divides and whenever an organism reproduces
ways humans have degraded natural capital
reducing biodiversity, eliminating natural predators, disrupting natural chemical cycling & energy flow
coevolution of bats and moths
some real-life savagery: bats use echolocation (high-frequency sound that bounces off objects) to locate their prey, moths. as a result, moths evolved ears sensitive to the sound frequencies that bats use so they could try to escape. then, bats countered the moths by changing their frequency of their sound pulses. in return, some moths evolved their own high-frequency to jam the bats' echolocation systems. some bat species have then adapted by turning off their echolocation systems & using the moths' clicks to locate their prey
endemic species
species that are only found in one area; especially vulnerable to extinction (exist on islands/ tropical rain forests where they have a specialized role/ unique areas- which is why it's unlikely for them to be able to migrate or adapt (ex. amphibians)
nonnative species
species that migrate into, or are intentionally or accidentally introduced into an ecosystem, can spread rapidly if they find a new location w/ favorable conditions **also known as invasive, alien or exotic species nonthreatening- chicken, cattle, domesticated plants threatening (can compete with/ reduce community's native species)- african honey bees= displaced some native honeybee populations, which reduced honey supply
indicator species
species that provide early warnings of damage to a community or ecosystem
aquatic limiting factors
temperature, sunlight, nutrient availability, acidity, and low levels of oxygen gas in water salinity
example of a keystone species from case study
the american alligator is a keystone species because it plays many important roles in ecosystems (ex. they dig deep depression, "gator holes" that hold fresh water during dry periods, which serves as refuges for aquatic life and a supply of freshwater/food for fishes, insects, birds, etc. the holes also kept the shores free of invading vegetation; w/o this service, ponds/ coastal wetlands where alligators live would be filled w/ shrubs and many species would disappear from these ecosystems) in the 1930s, hunters began killing large #'s of this animal for meat, its skin, or sport. by the 1960s, poachers had wiped out 90% in Louisiana & Florida. 1967, alligator placed on endangered species list; 1977 was protected & making a comeback
species evenness
the approximate amount of individuals each species presents, thus, the more even of an amount of individuals in a species each community has, the higher the species evenness (ex. tree farms have a huge amount of one type of tree that outnumbers the already low amount of other plant species on the farm. this uneven balance of tree and plant species makes it have a low species evenness.)
total fertility rate (TFR)
the average number of children born to the women in a population during their reproductive years
replacement-level fertility rate
the average number of children that couples in a population must bear to replace themselves (slightly higher than 2 per couple because some children die before reaching their reproductive years) *any fertility above the replacement level will cause a population to grow
stability
the capacity to withstand external stress and disturbance which is maintained only by constant change in response to changing environmental conditions
environmental resistance
the combination of all factors that act to limit the growth of a population; determines carrying capacity
carrying capacity
the maximum population of a given species that a particular habitat can sustain indefinitely growth rate of a population decreases as its size nears the carrying capacity of its environment because resources begin to dwindle
ecological succession
the normally gradual change in species composition in a given area in response to changing environmental conditions (ex. fires, volcanic eruptions, climate change)- tends to increase the biodiversity of ecosystems by increasing species richness & interactions among species, which enhances sustainability by promoting population control + by increasing the complexity of food webs reflects ongoing struggle by different species for key resources
when a population exceeds its carry capacity
the population suffers a harsh decline unless part of the population can switch to new resources or move to an area that has more resources
biological evolution (or also known as "evolution")
the process in which earth's life changes over time through changes in the genes of populations of organisms in following generations
background extinction rate
the rate at which species go extinct; annual background extinction rate has been about .0001% per year (if 10 million species on earth, about 10 would go extinct every year)
geographic isolation ->reproductive isolation -> speciation
the separated groups of the same species begin to live under different circumstances than each other, which cause them to adapt differently and develop unique characteristics. As a result, the isolate populations of the species may become so different in genetic makeup that they cannot produce offspring if they are rejoined
functional diversity
the variety of processes (ex. energy flow and matter cycling) that occur within ecosystems when species interact with each other in food chains and webs
Biodiversity
the variety of the earth's species, the genes they contain, the ecosystems in which they live, and the ecosystem processes (ex.nutrient cycling) that sustain all life
genetic diversity
variety of genes found in a population or in a species; enables life on earth to survive and adapt to environmental changes
local extinction
when a species become extinct over a large region, but not everywhere on earth
generalist and specialist species- which is better?
when environmental conditions are fairly constant, specialist species have an advantage because they have fewer predators. however, under rapidly changing conditions (like c-h-i-n-a-'s ignorance that's screwing everyone over), specialists are basically screwed and it's better to be a generalist species that can easily adapt
parasitism
when one species (the parasite) feeds on another organism (the host), usually by living on or inside the host. the parasite benefits and the host is harmed but not immediately killed (ex. ticks and fleas)
speciation
when one species splits into 2 or more different species- can lead to an entirely new species. for sexually reproducing organisms, a new species forms when one population of a species has evolved to the point where its members can no longer breed and produce fertile offspring with members of another population that did not change/ evolved differently
genetic resistance and hand sanitizer
when using hand sanitizer, you're basically forming Natural Selection on your hand. The bacteria that was blessed with the heritable trait of being immune to the chemicals in the hand sanitizer (the .1% in the "this sanitizer kills 99.9% of all bacteria!") is going to live longer than the ones who weren't blessed, and thus be able to find and rapidly mate with other blessed bacteria and create a bunch of little blessed immune bacteria. After a while, you're just going to have a bunch of immune bacteria on you and the sanitizer won't work any more #nochill
what affects the number of children women have
where they live/ their economic status; average age at marriage; availability of legal abortions; religious beliefs, cultural norms, traditions *tend to have fewer when a women has access to educated and paid employment
