Evolution and Mechanisms of Evolutionary Change – Lecture Review

A set of Q&A flashcards covering definitions, mechanisms, types of selection, evidence, and key historical influences related to evolutionary theory.

What are the five key steps in the basic process of evolution (often summarized as VCSRG)?

Variation, Competition, Survival, Reproduction, and passing on beneficial Genes.

Why do members of a species show variation?

Because they possess different genes from one another.

In evolution, what does ‘fitness’ refer to?

The ability of an individual to survive and reproduce in its environment.

According to Darwin, what produces fitness?

Adaptations—heritable traits that improve survival or reproduction.

Define natural selection.

The process by which organisms better suited to their environment survive and reproduce more successfully.

What is immigration in evolutionary terms?

Individuals entering a population, introducing new genes.

What is emigration in evolutionary terms?

Individuals leaving a population, resulting in loss of genes.

Explain artificial selection.

Humans selectively breeding plants or animals to obtain desirable traits.

What is a mutation?

A change in DNA; it can be beneficial, neutral, or harmful.

Describe a genetic bottleneck.

A sharp reduction in population size that changes allele frequencies.

What is the founder effect?

When a small group breaks off to start a new population with different allele frequencies.

What is non-random mating and its evolutionary consequence?

Mating based on specific traits, increasing the frequency of those traits in the population.

Define convergent evolution.

Unrelated species independently evolve similar traits due to similar environmental pressures.

Define divergent evolution.

Related species evolve different traits because they inhabit different environments.

What is coevolution?

Two species evolve in response to one another due to close ecological interactions.

Explain punctuated equilibrium.

Species remain unchanged for long periods then undergo rapid evolutionary change in short bursts.

State the VISTA summary of natural selection.

Variation, Inheritance, Selection for survival, Time, Adaptation.

What is stabilizing selection?

Natural selection that favors average traits and reduces extremes.

What is disruptive selection?

Natural selection that favors extreme traits at both ends, selecting against the average.

What is directional selection?

Natural selection that favors one extreme, shifting the population’s trait average in one direction.

Which three incorrect ideas did Lamarck propose?

Desire to change, use and disuse, and inheritance of acquired traits.

Name two scientists or concepts that influenced Darwin’s thinking.

Charles Lyell’s ancient, slowly changing Earth and farmers’ artificial selection; (also Malthusian competition).

What is meant by ‘descent with modification’?

Over generations, natural selection produces organisms with new structures or traits descended from ancestral forms.

Define adaptation.

An inherited characteristic that increases an organism’s chance of survival or reproduction.

What is a fossil and why is it considered direct evidence of evolution?

Preserved remains or traces of past life found in rock layers; show historical forms and transitions.

How is the relative age of rock layers determined?

By their position in a geologic column (stratigraphy).

How is the absolute age of a rock determined?

Through radioactive dating of the minerals it contains.

List three types of indirect evidence for evolution.

DNA comparisons, embryological similarities, and vestigial, homologous, or analogous structures.

Differentiate organic and inorganic compounds.

Organic compounds contain carbon–hydrogen bonds; inorganic compounds generally do not.

During Earth’s formation, where did the densest elements concentrate?

They sank to form Earth’s core.

What formed Earth’s first solid crust?

Less-dense elements floated upward and cooled at the surface.

Define population in evolutionary biology.

A group of individuals of the same species living in the same place at the same time.

What is meant by ‘survival of the fittest’?

Individuals best adapted to their environment outcompete others for resources and reproduce more successfully.

Why are no two organisms (except clones) genetically identical?

Genetic variation from mutation, recombination, and independent assortment creates diversity.

Give one example of convergent evolution in nature.

The wings of birds and bats evolving independently for flight.