Natural Selection and Microevolution in Action

Vocabulary flashcards covering ecological and evolutionary concepts, including natural selection events, character displacement, genetic adaptation, and the extended phenotype.

Adaptive radiation

The rapid diversification of a lineage into multiple species filling different ecological niches upon arriving in a new or unoccupied environment, such as an archipelago.

Vegetarian finch

An early offshoot of Darwin's finches characterized by a relatively large, chunky body and digestive tract adapted to consume and slowly digest leaves and whole plant organs.

Drought of 1977

A severe Galápagos drought documented by Peter and Rosemary Grant where survival favored medium ground finches with deeper beaks (between $9.3\,\text{mm}$ and $10.3\,\text{mm}$), shifting the mean beak depth upward by about $0.5\,\text{mm}$.

Drought of 2004

A Galápagos selection event where interspecific competition with newly colonized large ground finches for large seeds caused smaller medium ground finches with smaller beak depths to have higher survival.

Competitive exclusion

The ecological principle stating that two species competing for the exact same limiting resources cannot coexist in the same space at the same time.

Character displacement

An evolutionary divergence in morphology or resource use that occurs when two competing species overlap in range, minimizing niche competition.

Green anole

A reptile native to the southeastern United States that typically perches low on bushes ($\approx 80\,\text{cm}$) but shifted its habitat height up to $120\,\text{cm}$ or higher and evolved larger toe pads after brown anoles were introduced.

Pacific house gecko

An introduced gecko species in the southern United States characterized by clonal reproduction, enabling single individuals to rapidly establish and expand populations without a mate.

Homoplasy

A shared trait that evolved independently in separate lineages rather than being inherited from a common ancestor, such as the light coat color in beach mice evolving separately on the Gulf Coast and Atlantic Coast.

Polyphyletic group

A group of organisms categorized together based on superficial traits (such as light coat color in beach mice) that do not share a unique common ancestor possessing that trait.

Agouti gene

A gene located on chromosome $4$ acquired by snowshoe hares from jackrabbits via introgressive hybridization that disables the white winter molt, keeping the winter coat brown.

Fitness landscape

A multidimensional model mapping how combinations of multiple traits (such as birth mass and gestation period) simultaneously interact to determine an organism's survival or reproductive success.

Extended phenotype

A phenomenon where an organism's genes influence phenotypes outside its physical body, illustrated by gall-fly larvae whose chemical secretions induce plant tissue to construct a protective gall.