Chapter 13: How Populations Evolve

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

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20 Terms

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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.

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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.

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What are homologous structures?

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

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Define vestigial structures.

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

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What are analogous structures?

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

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What is convergent evolution?

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

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What is the significance of similar embryonic structures in vertebrates?

Evidence for common descent

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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

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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

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Explain how continental drift influences the distribution of organisms.

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

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What events may have caused mass extinctions?

Asteroid impact or volcanic activity

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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.

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What are the main causes of evolutionary change?

Natural selection, genetic drift, and gene flow

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What does natural selection lead to?

Adaptive evolution

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What is sexual selection?

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

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What are the two types of sexual selection?

Intrasexual selection and intersexual selection

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How does diploidy preserve variation?

By “hiding” recessive alleles

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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.

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What causes genetic variation?

Mutations, crossing over, independent orientation, and random fertilization

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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