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Final Chp 16
| Question | Answer |
|---|---|
| ecology and its levels | -the study of interactions of organisms and their environment -different levels: -individual (same species) -population (same species) -community (different species) -ecosystem (everything even non-living) |
| population ecology | -the study of interactions between populations of organisms and their environments -specifically focuses on their patterns of growth and how they are influenced by other species and by environmental factors |
| reproduction | -species typically reproduce 2 stable offspring -basically "replacing" itself -if they produced more, its population would grow and grow |
| growth rate | -the change in the number of individuals in the population in some unit of time -number in the population (N), growth rate per capita (r)-birth rate minus death rate -GR=rxN |
| exponential growth | -occurs when each individual replaces more than the single offspring needed to replace itself |
| why ecology? | -some things cannot be observed at an individual level: -ecological processes -human needs -species characteristics |
| as population increases... | -species experience: -reduced food supplies -less places to live and breed -increased incidence of parasites and diseases -increased predation risk |
| population density | -number of individuals in an area |
| density-dependent factors | limitations of a populations growth that are a consequence of population density |
| carrying capacity | -the limit of population growth (K) |
| logistic growth | -when a population starts growing exponentially, but as it reaches carrying capacity it slows down -S-shaped curve |
| density-independent factors | -also slow down population growth, but typically weather related -floods, earthquakes, hurricanes |
| population oscillations | -snowshoe hare and lynx: -hare population grows, providing more food for lynx -which then make lynx reproduce at a higher rate, causing them to eat more hares -which reduce the hare population, causing lynx to fall -letting hares reproduce again |
| maximum sustainable yield | -the maximum number you can cut of a population without affecting its growth (half the carrying capacity) |
| life histories | -a species' vital statistics, set details that tell us about the species -three kinds: -big-bang -fast-intensive -slow-gradual |
| what it includes (life histories) | -age at first reproduction -probabilities of survival -litter size and frequency -longevity |
| big bang | -Antechinus (mouse) -reaches sexual maturity at one year -mates intensely over a 3 week period -males die shortly after mating -females usually die after weaning their first litter |
| fast-intensive | -House mouse -reaches sexual maturity at one month -produces litters of 6-10 offspring every month |
| slow-gradual | -Little brown bat -reaches sexual maturity at one year -produces about one offspring per year |
| is there a best life history? | -consider two questions: 1. What is the cost of the reproductive investment during any reproductive episode? -producing offspring is risky 2. What is an individual’s likelihood of surviving to have future reproductive episodes? -whichever works best |
| ideal life history | 1. produce many offspring 2. grow extremely large (avoid predation) 3. life forever |
| life history trade offs | 1. reproduction and survival 2. reproduction and growth 3. number and size of offspring |
| reproduction and survival | -big bang reproducers, such as salmon, make a single extremely large investment in reproduction before dying |
| reproduction and growth | -beech trees grow much more slowly in the years they produce many seeds than in the years when they produce fewer seeds |
| number and size of offspring | -female lizards produce medium sized eggs as a compromise between a large number of small eggs and few large eggs |
| lfie table | A table presenting data on the mortality rates within defined age ranges for a population |
| survivorship curves | graph showing the proportion of individuals of a particular age that are now alive in a population |
| curve type 1 | -high survivorship until old age, then rapidly decreasing survivorship (normal life) -typically have few predators and produce few offspring so they can care for them |
| curve type 2 | -survivorship decreases at a steady, regular pace -typically birds, the rate of dying at any age is the same |
| curve type 3 | high mortality early in life, but those who survive live long lives -common in plants and insects -typically produce many offspring, many do not survive, and they don't really care for the ones that do |
| why we age | -alleles that cause death early in life are "weeded out" by natural selection and only good alleles remain |
| age pyramids | -less developed: appear more triangular due to high birth rates and then high death rates in older individuals -industrial: appear more rectangular due to low birth rates and low death rates in older individuals |
| demographic transition | -pattern of population growth characterized by the progression from high birth and death rates (slow growth) to high birth rates and low death rates (fast growth) to low birth and death rates (slow growth |
| demographic 1 | -slow growth: -population have low food supply and lack reliable health care leading to high birth rates and high death rates |
| demographic 2 | -fast growth: -industrialization begins leading to better health care and more food -high birth rates but low death rates so rapid growth |
| demographic 3 | -slow growth: -industrialization continues so higher education and employment leading to lower birth and death rates |
| increasing carrying capacity | -expanding into new habitats -increasing the agricultural productivity on land -finding ways to live at higher densities |
| ecological footprint | -an estimate to how many resources an individual or country uses: -land -electricity -food -fuel |
Created by:
tcas