Patterns of Evolution & Speciation – Review Flashcards

26 Q&A flashcards covering divergent & convergent evolution, coevolution, speciation, evolutionary theories, mechanisms, and illustrative examples from lecture notes.

What is divergent evolution?

The process in which one ancestral species splits into two or more descendant species that become increasingly different, producing homologous structures.

What kind of structures result from divergent evolution?

Homologous structures—features with different appearances or functions but the same underlying anatomy inherited from a common ancestor.

Give an example of homologous structures produced by divergent evolution.

The forelimbs of humans, cats, whales, and bats, which have the same bone layout (humerus, radius, ulna, etc.) but different functions.

What is convergent evolution?

Evolution in which unrelated species independently evolve similar traits because they live in similar environments or occupy similar niches.

What are analogous structures?

Traits that look or function similarly in different species but evolved independently and do not share the same underlying structure or origin.

Give an example of analogous structures created by convergent evolution.

The wings of butterflies (insects) and bats (mammals).

Define coevolution.

A process in which two or more species reciprocally affect each other’s evolution, often because of close ecological interactions.

List four types of species interactions that commonly drive coevolution.

1) Predator–prey, 2) Parasite–host, 3) Competitive species, 4) Mutualistic species.

How do bees and flowering plants illustrate coevolution?

Plants evolved specialized flowers to attract bees for pollination, while bees evolved behavioral and structural traits to gather nectar/pollen, benefiting both species.

Describe the theory of gradualism.

Evolutionary change occurs slowly, continuously, and steadily, with constant environmental pressures causing small changes that accumulate over long timescales.

Describe the theory of punctuated equilibrium.

Species remain relatively unchanged for long periods (stasis) punctuated by brief, rapid bursts of evolutionary change often triggered by mutation or catastrophic events.

What is microevolution?

Small-scale evolutionary change within a population or species, such as shifts in allele frequencies over generations.

What is macroevolution?

Large-scale evolutionary patterns and processes above the species level, including the origin, diversification, and extinction of lineages over geologic time.

Name four basic mechanisms that drive evolution.

Mutation, gene flow (migration), genetic drift, and natural selection.

What key step begins the process of speciation?

The separation of the gene pool of two populations so they no longer share genes freely.

What is allopatric speciation?

The formation of a new species when populations are geographically isolated, restricting gene flow and allowing divergence through mutation, drift, and selection.

What is sympatric speciation and where is it most common?

Speciation that occurs without geographic separation, typically through reproductive isolation within the same area; it is more common in plants.

Name three main types of reproductive isolation.

Geographic isolation, behavioral isolation (differences in courtship or mating behavior), and temporal isolation (breeding at different times).

Define adaptive radiation.

The rapid evolution of a single ancestral species into many new species, each adapted to exploit a different ecological niche.

Why are Darwin's Galápagos finches considered an example of adaptive radiation?

A founding population diversified into multiple species with different beak sizes and shapes, each specialized for distinct food sources on the islands.

What is the founder effect?

Genetic drift that occurs when a small group colonizes a new habitat, carrying only a subset of the genetic diversity from the original population.

Define gene flow.

The movement of alleles into or out of a population via immigration or emigration of individuals, which can introduce new genetic variation.

Give two reasons for non-random mating in a population.

Geographic proximity and active mate choice for specific traits such as color, size, symmetry, or dominance.

How do crossing-over and gene shuffling during sexual reproduction influence evolution?

They increase genetic variation by creating new combinations of alleles in offspring, supplying material for natural selection.

In the rock-colored mouse example, which phenotype has higher fitness and why?

Black mice, because they blend into the dark rocks, making them less visible to predatory birds and more likely to survive and reproduce.

What two conditions did the Grants show are necessary for beak evolution in Galápagos finches?

1) Heritable variation in beak traits; 2) Differences in beak size/shape must affect fitness so natural selection can favor certain beaks.