Campbell Biology: Concepts & Connections - Chapter 13: How Populations Evolve

Flashcards based on Campbell Biology: Concepts & Connections Tenth Edition Chapter 13 lecture notes, focusing on evolution, Darwin's theory, and mechanisms of microevolution.

What explains the diversity of life, according to the lecture notes?

The theory of evolution, which states that living species are descendants of ancestral species that differed from present-day ones.

What is Darwin's theory of descent with modification?

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

What is the definition of fossils?

The imprints or remains of organisms that lived in the past, documenting differences between past and present organisms, and revealing that many species have become extinct.

What are transitional fossils?

Fossils that link early extinct species with species living today, providing evidence for evolutionary origins of different groups of organisms.

What are homologous structures?

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

What are vestigial structures?

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

What are analogous structures?

Structures that are outwardly similar in appearance and function but differ in their evolutionary origin (not derived from a common ancestor).

What is convergent evolution?

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

What evidence does comparative embryology provide for evolution?

Common embryonic structures in different animal species reveal similarities not visible in adult organisms, providing evidence for common descent.

What molecular evidence supports the theory of evolution?

All organisms share related biochemical processes, such as using DNA as the genetic blueprint, RNA, ribosomes, and the same genetic code for translation, and ATP to transfer energy.

What is the essence of Darwin's theory of natural selection regarding reproduction?

Differential success in reproduction; organisms produce more offspring than the environment can support, vary in inherited characteristics, and those best adapted are more likely to survive and reproduce, leading to gradual change in population characteristics.

What is the significance of continental drift in evolution?

Continental drift has influenced the distribution of organisms and greatly affected the history of life, where continental mergers triggered extinctions, and separations caused isolation and diversification.

What are the three key statements about natural selection?

1. Evolution occurs at the population level. 2. Natural selection can amplify or diminish only heritable traits. 3. Evolution is not goal-directed; it does not lead to perfectly adapted organisms.

What are the ultimate sources of the genetic variation?

Mutations are the ultimate source of the genetic variation, and causes variation with crossing over, independent orientation of homologous chromosomes, and random fertilization.

What is a population in evolutionary terms?

A group of individuals of the same species that live in the same area and interbreed.

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, no gene flow, and no natural selection.

What are the three main causes of evolutionary change?

Natural selection, genetic drift, and gene flow.

What is the bottleneck effect?

When genetic drift leads to a loss of genetic diversity when a population is greatly reduced.

What is the founder effect?

Genetic drift in which a few individuals colonize an island or other new habitat.

What is relative fitness?

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

What are the three ways natural selection can affect the distribution of phenotypes in a population?

Stabilizing selection (favors intermediate phenotypes), directional selection (shifts overall makeup of the population by acting against individuals at one extreme) and disruptive selection (favors individuals at both ends of a phenotypic range).

What is sexual selection?

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

What is intrasexual selection?

A form of natural selection in which individuals compete directly with members of the same sex for mates.

What is intersexual selection?

A form of natural selection (mate choice) describing how individuals of one sex are choosy in selecting their mates based on the traits of the opposite sex.

How does diploidy preserve genetic variation?

By 'hiding' recessive alleles, making them less subject to selection.

What is heterozygote advantage?

A type of balancing selection in which heterozygous individuals have greater reproductive success than either type of homozygote, maintaining two or more alleles for a gene in the population.

What is balancing selection?

Balancing selection occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population.

What is the summary of why natural selection cannot fashion perfect organisms?

1. Selection can act only on existing variations. 2. Evolution is limited by historical constraints. 3. Adaptations are often compromises. 4. Chance, natural selection, and the environment interact unpredictably.