Mechanisms of Evolution(1) (1)

Mutation

A change in the organism’s DNA; can affect somatic or germ line tissues.

Microevolution

Evolutionary change within a lineage, which occurs continuously on small scales.

Macroevolution

The origin and extinction of lineages, occurring over long periods.

Genetic Drift

The change in allele frequencies that occurs by chance events, particularly strong in small populations.

Founder Effect

A special case of genetic drift when a few individuals establish a new population.

Bottlenecks

Periods of very low population size that reduce genetic variation.

Allele Flow (Gene Flow)

The transfer of alleles between populations as individuals migrate.

Natural Selection

The differential survival and reproduction of individuals with certain traits based on their phenotypes.

Directional Selection

Selection that favors one extreme phenotype, leading to a shift in allele frequencies.

Stabilizing Selection

Selection that favors intermediate phenotypes and reduces variation.

Disruptive Selection

Selection that favors extreme phenotypes over intermediate ones.

Kin Selection

A form of natural selection that favors behaviors that increase the reproductive success of relatives.

Inclusive Fitness

An individual's total contribution to the gene pool of the next generation, considering their own offspring and that of relatives.

Assortative Mating

A nonrandom mating pattern where individuals select mates based on shared traits.

Inbreeding

Mating between closely related individuals that can lead to a loss of heterozygosity.

Neutral Theory of Molecular Evolution

A theory positing that the majority of evolutionary changes at the molecular level are caused by genetic drift of neutral mutations.

Epistasis

Interaction between different genes, where the effect of one gene depends on the presence or absence of another gene.

Frequency-Dependent Selection

A type of selection where the fitness of a phenotype depends on its frequency relative to other phenotypes.

Mimicry

When one organism evolves to resemble another organism to gain an advantage such as protection from predators.

Adaptation

A trait that enhances the survival and reproduction of organisms in a specific environment.

Speciation

The process by which new species arise, often due to reproductive isolation.

Extinction

The permanent loss of all members of a species, often due to environmental changes.

What is kin selection?

A form of natural selection that favors behaviors that increase the reproductive success of relatives.

Why is kin selection important in evolution?

Kin selection helps explain altruistic behaviors that benefit relatives, thus enhancing inclusive fitness.

What is inclusive fitness?

An individual's total contribution to the gene pool of the next generation, considering their own offspring and that of relatives.

How does kin selection relate to the concept of altruism?

Kin selection can drive individuals to act altruistically towards relatives, improving the chances of shared genes being passed on.

What are examples of kin selection in nature?

Examples include worker bees sacrificing their reproduction for the queen and elephants caring for their young and relatives.

High Allele Flow

Occurs when there is significant exchange of alleles between populations, leading to increased genetic diversity.

Low Allele Flow

Occurs when there is minimal exchange of alleles between populations, potentially leading to genetic differentiation and isolation.

Natural Selection

The process by which individuals with favorable traits are more likely to survive and reproduce.

Molecular Clock

A technique that uses the mutation rate of genes to estimate the time of evolution among species.

What role does natural selection play in evolution?

Natural selection drives the adaptation of populations to their environments by favoring beneficial traits.

How is the molecular clock used in evolutionary biology?

It provides a timeline for evolutionary events based on the genetic differences between species.

What factors can affect the molecular clock?

Factors include mutation rates, selection pressures, and environmental changes over time.

Why is understanding natural selection important?

It helps explain the diversity of life and the adaptation of organisms to their environments.

What assumptions does the molecular clock method rely on?

It assumes that mutations accumulate at a relatively constant rate over time.