Biology for a Changing World Chapter 15

population genetics

the study of the genetic makeup of populations and how genetic composition of a population changes

gene pool

total collection of alleles in a population

allele frequency

relative proportion of an allele in a population

nonadaptive evolution

any change in allele frequency that does not by itself lead a population to become more adapted to its environment

causes: mutation, genetic drift, and gene flow

genetic drift

random changes in the allele frequencies of a population between generations, more dramatic effect on small populations

founder effect

type of genetic drift in which a small number of individuals leaves one population and established a new population, by chance the new population may have lower genetic diversity

bottleneck effect

a type of genetic drift that occurs when a population is suddenly reduces to a small number and alleles are lost

gene flow

movement of alleles from one population to another, may increase genetic diversity

inbreeding

mating with closely related individuals, does not change allele frequency, increases heterozygotes

inbreeding depression

negative reproductive consequences for a population associated with homozygous recessive individuals

Hardy-weinberg equilibrium

principle, in a non-evolving population, both allele and genotype frequencies remain constant in generations

Hardy-weinburg equation

mathematical formula that calculates frequency of genotypes and phenotypes one would expect in a non-evolving population

biological species concept

definition of a species as a population whose members can interbreed

reproductive isolation

mechanisms that prevent mating and gene flow between two/more species

speciation

genetic divergence of populations leading to reproductive isolation

A population of 3,200 mice has 4,200 dominant G alleles and 2,200 recessive g. What is the frequency of g alleles in the population?

3,200/6,400= allele frequency of .34

What are examples of genetic drift?

founder effect and bottleneck effect

Why is interbreeding detrimental?

Can cause two harmful recessive alleles in offspring, reduces heterozygotes

A species is defined as what?

Able to mate and produce fertile offspring

How does geographic isolation contribute to speciation?

When populations are geographically separated they can't exchange alleles and mutations stay within a population. The two populations could overtime not be able to breed due to evolution.