Chapter 13: How Populations Evolve

Flashcards for reviewing key concepts in evolution, including Darwin's theory, evidence for evolution, mechanisms of evolution, and natural selection.

What is the theory of evolution?

The idea that living species are descendants of ancestral species that were different from present-day ones, explains the diversity of life.

What does Darwin's theory of descent with modification explain?

All of life is connected by common ancestry and descendants have accumulated adaptations to changing environments over vast spans of time.

What are homologous structures?

Features that often have different functions but are structurally similar because of common ancestry

Define vestigial structures.

Remnants of features that served important functions in an organism’s ancestors.

What are analogous structures?

Structures that are outwardly similar in appearance and function, but differ in their evolutionary origin, not of a common ancestor.

What is convergent evolution?

Occurs when similar environmental pressures and natural selection give rise to similar (analogous) structures in distantly related organisms

What is the significance of similar embryonic structures in vertebrates?

Evidence for common descent

What is the significance of comparing DNA and amino acid sequences between different organisms?

Reveals evolutionary relationships; strong evidence that all life forms are related

What biochemical processes are shared by all organisms?

All cells use DNA as genetic blueprint; all use RNA, ribosomes, and approximately the same genetic code for translation; all use roughly the same set of 20 amino acids to build proteins; all use ATP to transfer energy

Explain how continental drift influences the distribution of organisms.

Continental mergers triggered extinctions; separation of continents caused the isolation and diversification of organisms.

What events may have caused mass extinctions?

Asteroid impact or volcanic activity

What are the three key points about evolution by natural selection?

Evolution occurs at the population level; natural selection can amplify or diminish only heritable traits; evolution is not goal directed; it does not lead to perfectly adapted organisms.

What are the main causes of evolutionary change?

Natural selection, genetic drift, and gene flow

What does natural selection lead to?

Adaptive evolution

What is sexual selection?

A form of natural selection in which individuals with certain characteristics are more likely than other individuals to obtain mates.

What are the two types of sexual selection?

Intrasexual selection and intersexual selection

How does diploidy preserve variation?

By “hiding” recessive alleles

What are the constrains on the evolutions of organisms?

Selection can act only on existing variations; evolution is limited by historical constraints; adaptations are often compromises; Chance, natural selection, and the environment interact.

What causes genetic variation?

Mutations, crossing over, independent orientation, and random fertilization

What does the Hardy-Weinberg equilibrium state?

Allele and genotype frequencies will remain constant if a population is large, mating is random, there is no mutation, there is no gene flow, and there is no natural selection