Ch 19 Evolutionary Change in Populations

Evolution occurs in __________, not individuals

populations

Population genetics

the study of genetic variability within a population and of the evolutionary forces that act on it

A populations gene pool includes all the _______ for all the ____ present

alleles, loci

Diploid organisms have ___ alleles at each genetic locus

two

Each individual has a different subset of _______ in the gene pool

alleles

The sum of all genotype frequencies is

1.0

Phenotype frequency

the proportion of a particular phenotype in the population

If two alleles are dominant and recessive, the dominant phenotype is the sum of…

two genotypes (AA & Aa)

Allele Frequency

the proportion of a specific allele (A or a) in a particular population

A population of 1000 individuals carries ______ alleles

2000

The Hardy-Weinberg principle states that…

frequencies of alleles and genotypes in a population do not change from generation to generation unless influenced by outside factors

Genetic equilibrium

a population with no net change in allele or genotype frequencies overtime

If allele frequencies DO change over successive generations, evolution is/is not occuring

is occuring

Godfred Hardy and Wilhelm Weinberg mathematically described the expected frequencies of…

various genotypes in a population at genetic equilibrium

If only two alleles, A and a, exist at a locus, the sum of their frequencies in a population must equal __

p + q = _

1

p = frequency of the ______ allele (?)

q = frequency of the ______ allele (?)

dominant (A)

recessive (a)

Genetic equilibrium exists only when five conditions are met:

random mating, no net mutations, large population size, no migration, and no natural selection

Microevolution

relatively small generation-to-generation changes in allele or genotype frequencies within a population

There are five microevolutionary processes, the opposite conditions for genetic equilibrium

nonrandom mating, mutation, genetic drift, gene flow, natural selection

Inbreeding

mating of individuals who are more closely related than if they had been chosen at random from the population

Nonrandom mating changes…

genotype frequencies

Inbreeding can increase the frequency of _______________, and may cause inbreeding depression:

homozygous genotypes, inbred individuals have lower fitness than those not inbred

Assortative mating

individuals select mates by their phenotypes

Assortative mating changes genotype frequencies only…

at the loci inolved in mate choice

Selection of mates with the same phenotype is _______ assortative mating

positive

Selection of mates with opposite phenotypes is ________ assortative mating

negative

Non-random mating

choosing mates based on preferred characteristics

Nonrandom mating occurs when some individuals have _______ chances of reproducing than other individuals in the popula

higher

Mutation

a change in DNA, the source of genetic variation in a population

When a polypeptie is sufficiently altered to change its function, the mutation is usually ________

harmful

Random evolutionary changes in small breeding populations changes allele frequencies: decreases ______________ within a population, but increases __________________ among different populations

genetic variation, genetic differences

Bottlenecks

A population may rapidly and severely decrease due to disease, exploitation, or sudden environmental change

Founder effect

Genetic drift that results when a few individuals from a large population found a new colony