Biology: Chapter 19-The Evolution of Populations

allele frequency

(also, gene frequency) rate at which a specific allele appears within a population

assortative mating

when individuals tend to mate with those who are phenotypically similar to themselves

bottleneck effect

magnification of genetic drift as a result of natural events or catastrophes

cline

gradual geographic variation across an ecological gradient

founder effect

when a few individuals become isolated from a larger population and start a new population that only carries part of the original gene pool.

gene flow

flow of alleles in and out of a population due to the migration of individuals or gametes

gene pool

all of the alleles carried by all of the individuals in the population

genetic drift

effect of chance on a population's gene pool

genetic variance

diversity of alleles and genotypes in a population

geographical variation

differences in the phenotypic variation between populations that are separated geographically

heritability

fraction of population variation that can be attributed to its genetic variance

inbreeding

mating of closely related individuals

inbreeding depression

increase in abnormalities and disease in inbreeding populations

macroevolution

broader scale evolutionary changes seen over paleontological time

modern synthesis

overarching evolutionary paradigm that took shape by the 1940s and is generally accepted today

nonrandom mating

changes in a population's gene pool due to mate choice or other forces that cause individuals to mate with certain phenotypes more than others aka [going to change a populations gene pool bc ur only mating with certain ppl over others]

population genetics

study of how selective forces change the allele frequencies in a population over time

What are the 5 conditions for Hardy-Weinberg equilibrium?

no mutation, large population, random mating, no migration, no naturla selection

What do p and q represent in Hardy-Weinberg?

p is the frequency of the more common allele
q the frequency of the less common allele

What does the equation p² + 2pq + q² = 1 describe?

• p and q are the frequencies of alleles in a population

• p² and q² are the frequencies of individuals that are homozygous (i.e. AA or aa)

• 2pq is the frequency of heterozygous individuals (i.e. Aa)

How can you calculate allele frequency from a population?

count alleles

Can populations meet Hardy-Weinberg conditions in reality?

rarely

What are the 5 mechanisms by which evolution occurs?

Natural selection, Gentic drift, gene flow, non-random mating, mutation

What is genetic drift and when is it strongest?

When chance events can cause fluctuations in allele frequencies and its strongest in small populations

How do founder and bottleneck effects relate to drift?

they both reduce variation and affect allele frequency

What is the movement of alleles into/out of populations?

gene flow

What is mating between similar individuals called?

assortative mating

Can phenotypes be non-heritable? Give an example trait. (look at the slide for this and put on card)

yes, caterpillar diet

What theory explains rapid changes followed by stasis?

punctuated equilibrium

What was the Cambrian Explosion?

major example of punctuated equilibria and likely caused by increased O2 in the environment

Why is Tiktaalik important in evolution?

transitional fossil that shows features of both fish and land animals (tetrapods)

What is a hominin?

early human relative

Who was 'Ardi'?

upright walker

What does 'Lucy' show about human movement?

bipedalism

What increased in early Homo species?

brain size

What is sexual dimorphism?

male-female size difference

When did Homo erectus leave Africa?

1.8 million years ago

Do modern humans have Neanderthal DNA?

yes, some people

What misused theory linked genetics to race/class?

social darwinism

What was eugenics?

forced breeding control - selective breeding to remove undesirable traits from the gene pool by killing or sterilization

Do racial groups differ significantly in DNA?

very little

What term is preferred over 'race' in genetics?

ancestry

How can race misconceptions affect medicine?

bias in care