BIO111 EXAM #3

At what level does evolution occur?

Population level, not individuals.

What is artificial selection?

Humans selecting organisms with desired traits to reproduce.

What is natural selection?

Individuals with beneficial traits survive and reproduce more successfully.

What is direct observation as evidence for evolution?

Changes seen through artificial selection in domesticated plants and animals.

What is fossil evidence?

Preserved remains showing changes in organisms over time.

What do shared characteristics indicate?

Common ancestry between organisms.

What is biogeographic evidence?

The geographic distribution of species supports evolution.

What do similar embryonic development patterns suggest?

Species share a common ancestor.

What are homologous traits?

Traits inherited from a common ancestor that may have different functions.

What are vestigial traits?

Structures that have lost their original function over time.

Can vestigial traits also be homologous?

Yes, because they come from a common ancestor.

How can DNA sequences be used as evidence for evolution?

More similar DNA means organisms are more closely related.

What are allele frequencies?

The proportion of a specific allele in a population.

How do you calculate allele frequency?

Divide the number of copies of the allele by the total number of alleles.

What are the four mechanisms of evolution?

Natural selection, mutation, gene flow, genetic drift.

What is mutation?

Random changes in DNA that create new variation.

What is gene flow?

Movement of alleles between populations.

What is genetic drift?

Random changes in allele frequencies, especially in small populations.

What is directional selection?

Favors one extreme phenotype.

What is stabilizing selection?

Favors intermediate phenotypes.

What is disruptive selection?

Favors both extreme phenotypes.

What is convergent evolution?

Unrelated species develop similar traits due to similar environments.

What are analogous traits?

Traits that are similar in function but not from common ancestry.

How does convergent evolution differ from common descent?

Convergent = no shared ancestor; common descent = shared ancestor.

What is a genetic bottleneck?

A sudden reduction in population size that reduces genetic diversity.

What is the founder effect?

A small group forms a new population with limited genetic variation.

What is biological fitness?

The ability to survive and reproduce.

What factors influence biological fitness?

Environment, competition, predators, resources, genetics.

What is the biological species concept?

Species are groups that can interbreed and produce fertile offspring.

Why is the biological species concept sometimes impractical?

It doesn't apply to asexual organisms or fossils.

What are the four modern criteria used to define a species?

Biogeography, DNA similarity, morphology, ability to interbreed.

What is morphology?

Physical structure and appearance of organisms.

What is genetic divergence?

Accumulation of genetic differences between populations.

How does genetic divergence lead to speciation?

Differences build up until populations can no longer interbreed.

What is allopatric speciation?

New species form due to geographic isolation.

What is sympatric speciation?

New species form without geographic isolation.

What are reproductive barriers?

Factors that prevent species from interbreeding.

What are prezygotic barriers?

Prevent mating or fertilization.

What are postzygotic barriers?

Occur after fertilization, leading to nonviable or infertile offspring.