Population GENETICS. Population Genetics Vocab list gene pool allele frequency genetic equilibrium genetic drift gene flow stabilizing selection directional.

Population GENETICS

Population GeneticsVocab list

gene pool

allele frequency

genetic equilibrium

genetic drift

gene flow

stabilizing selection

directional selection

disruptive selection

speciation

geographic isolation

reproductive isolation

gradualism

punctuated equilibrium

adaptive radiation

divergent evolution

convergent evolution

coevolution

Population GeneticsPopulation Genetics

Changes in evolution occur in populations, not individuals

Population GeneticsPopulation Genetics

•gene pool

–entire collection of genes in a population

•allele frequency

–number of times an allele appears in a gene pool

•genetic equilibrium

–gene pool which is not changing in allele frequencies

–a population at genetic equilibrium is not evolving

Population GeneticsMechanisms for Change

Change in small populations

•mutations

–introduces of new alleles into gene pool

Population GeneticsMechanisms for Change

•genetic drift

–random change in allele frequency over time

Population GeneticsMechanisms for Change

•gene flow

–increase of possible alleles between populations

–this can change the allele frequency of both populations

Population GeneticsMechanisms for Change

For larger populations natural selection is the significant factor which causes changes in allele frequency

Mechanisms for Change

Steps of Natural Selection

• In nature organisms produce more offspring than can survive.

Population Genetics

Population GeneticsMechanisms for Change

Steps of Natural Selection

2. In any population, individuals have variations.

Population GeneticsMechanisms for Change

Steps of Natural Selection

3. Individuals with certain useful variations survive in their environment, passing those variations to the next generation.

Population GeneticsMechanisms for Change

Steps of Natural Selection

4. Over time, offspring with certain variations make up most of the population and may look entirely different from their ancestors.

Population GeneticsNatural Selection

on one variation

•stabilizing selection

–selection against extremes, favors the average

Population GeneticsNatural Selection

on one variation

•directional selection

–selection against one extreme, favors other extreme

Population GeneticsNatural Selection

on one variation

•disruptive selection

–selection against average, favors both extremes

Population GeneticsEvolution of a Species

•speciation

–the production of two or more species

what leads to a new species?

•geographic isolation

–physical barrier which separates populations

Population GeneticsEvolution of a Species

what leads to a new species?

•reproductive isolation

–groups can no longer sexually reproduce

–ex: behavior, mating patterns, physical differences

Population GeneticsEvolution of a Species

Speed of speciation

•gradualism

–species evolve at a slow constant rate

Population GeneticsEvolution of a Species

Speed of speciation

•punctuated equilibrium

–rapid significant changes over a short time

Population GeneticsPatterns in Evolution

•adaptive radiation

–new species develop from a single common ancestor

Population GeneticsPatterns in Evolution

•divergent evolution

–new species develop from a single common ancestor

Population GeneticsPatterns in Evolution

•convergent evolution

–different species develop similar traits

Population GeneticsPatterns in Evolution

•co-evolution

–different species develop traits as a result of a close relationship with the other species