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18 terms

Ecology Exam 3 Study Guide

Population&Community Ecology
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What are the 3 types of population distribution?
random, regular, or clumped
What is the self-thinning law?
As organism size ↑ then population density ↓
What 3 factors determine Commonness
geographic range of species, habitat tolerance, local population size
What are the major environmental concerns relating to population biodiversity?
habitat fragmentation, habitat loss, invasive species, and climate change
What determines rarity?
least threatened by extinction, extensive geographic ranges, broad habitat tolerances, large local populations
What is evolution?
a change in allele frequencies over time
How does natural selection work?
-some individuals produce more offspring due to their phenotypic characteristic that live to reproduce
-works at the level of the individual who exists as part of a population
What are the results of the natural selection?
can favor, disfavor, or conserve genetic make-up of a population
Random or chance processes, such as genetic drift
can change gene frequencies in populations, especially in small populations.
How can changes in genotype proportions occur within a population? (2 principal processes)
1) Genetic drift - random fluctuations in frequency
2) Natural selection - nonrandom changes due to differential survival and reproduction
What is the Modern synthesis of evolution
natural selection (Darwin) + genetic inheritance (Mendel)
-when genetic factors cause differences in fecundity and survival among individuals
-Or differential survival and reproduction of individuals
What are adaptations?
are new traits shaped by NS
When is a mutation an adaptation?
When it improves the odds of surviving and reproducing in a particular environment
What are 2 assumptions of logistic and exponential growth models?
- All individuals are exactly the same (N).
- All individuals have the same reproductive capacity (r).
Why don't logistic and exponential growth models work for real populations?
- Age affects probabilities of giving birth and dying.
- Have different proportions of individuals in each age class.
What does a static life table do?
-considers survival of individuals of different ages during a single time interval.
What does a static life table require?
-Requires being able to distinguish ages.
-have to calculate births and deaths within each age class.
What is different about an age structured population and why do we use life tables in those cases?
we can't assume that ll individuals contribute equally to population so divide into dfferent age classes.