Ch. 26 - Population and Evolutionary Genetics

Klug - Concepts of Genetics 12th Edition

Klug12th EditionConcepts of Genetics ISBN: 9780135564776당신이 사용하는 게 아니라요?교과서 변경

Klug 12th Edition

Ch. 26 - Population and Evolutionary Genetics

문제 1d

26장, 문제 1d

How do we know when populations have diverged to the point that they form two different species?

검증된 단계별 안내

Understand the Biological Species Concept, which defines species as groups of interbreeding natural populations that are reproductively isolated from other such groups.

Examine reproductive isolation mechanisms, which can be prezygotic (before fertilization) or postzygotic (after fertilization), to determine if two populations can no longer produce viable, fertile offspring together.

Analyze genetic divergence by comparing DNA sequences or allele frequencies between populations; significant genetic differences can indicate speciation.

Consider ecological and behavioral differences that reduce gene flow, such as different mating calls, breeding seasons, or habitat preferences.

Integrate evidence from reproductive isolation, genetic data, and ecological factors to conclude whether the populations have diverged enough to be considered separate species.

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주요 개념

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Biological Species Concept

This concept defines species as groups of interbreeding natural populations that are reproductively isolated from other such groups. When populations can no longer produce fertile offspring together, they are considered separate species. It emphasizes reproductive barriers as the key factor in species divergence.

Reproductive Isolation Mechanisms

These are barriers that prevent gene flow between populations, including prezygotic (e.g., behavioral, temporal isolation) and postzygotic (e.g., hybrid inviability) mechanisms. The presence of these barriers indicates that populations have diverged enough to be considered distinct species.

Genetic Divergence and Speciation

Genetic divergence occurs when populations accumulate different mutations over time, leading to distinct genetic identities. This divergence can be measured using molecular markers, and significant genetic differences often correlate with speciation events, reflecting evolutionary separation.

관련 실천

교과서 질문

Price et al. [(1999). J. Bacteriol. 181:2358–2362] conducted a genetic study of the toxin transport protein (PA) of Bacillus anthracis, the bacterium that causes anthrax in humans. Within the 2294-nucleotide gene in 26 strains they identified five point mutations—two missense and three synonyms—among different isolates. Necropsy samples from an anthrax outbreak in 1979 revealed a novel missense mutation and five unique nucleotide changes among ten victims. The authors concluded that these data indicate little or no horizontal transfer between different B. anthracis strains.

Which types of nucleotide changes (missense or synonyms) cause amino acid changes?

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교과서 질문

How do we know how much genetic variation is in a population?

415

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교과서 질문

Write a short essay describing the roles of mutation, migration, and selection in bringing about speciation.

544

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How do we know whether the genetic structure of a population is static or dynamic?

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교과서 질문

How do we know the age of the last common ancestor shared by two species?

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교과서 질문

How do geneticists detect the presence of genetic variation as different alleles in a population?

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