Biotic Processes, Dispersal, and Biogeographical Patterns

Vocabulary flashcards covering dispersal mechanisms, evolutionary divergence, historical and ecological biogeography, and ecogeographical rules.

Passive dispersal

Dispersal in which individuals play no active role (such as rafting) and rely instead on external forces like wind, current, or other animals.

Active dispersal

The accumulation of ecological dispersal events in which individuals move through their own locomotion.

Corridor route

A dispersal pathway characterized by minimal resistance to passage between two areas, such as the connection between Europe and Asia.

Filter route

A dispersal route that permits certain taxa to pass through while blocking others, such as the Central American land bridge.

Sweepstakes dispersal

Dispersal occurring via flying or rafting that involves a low probability of success, such as hoary bats reaching Hawaii.

Mass extinction

A catastrophic extinction event that wipes out $70\text{--}80\%$ or more of species.

Adaptive radiation

A process of evolutionary diversification that occurs rapidly, produces many descendants, and is geographically restricted.

Convergent evolution

The process where natural selection produces similar body forms in distantly related species that inhabit similar environments.

Historical biogeography

The field that explains current species distributions using phylogeny and Earth's history, focusing on the evolution of past regions of occupancy.

Vicariance

The geographic separation of a population, typically caused by a physical barrier, that results in two closely related species.

Great American Interchange

The biotic exchange following the Pliocene reconnection of North and South America via a savanna-dominated filter route, resulting in $50\%$ of South American mammals having North American origin, while only opossums, porcupines, and armadillos survived in North America.

Island Rule

A biogeographical rule stating that small mammals evolve to become larger (due to fewer predators) and large animals evolve to become smaller (due to less food).

Rapoport’s Rule

A biogeographical pattern stating that the latitudinal breadth of species ranges increases from the equator toward the poles.

Bergmann’s Rule

A biogeographical rule stating that body size increases with latitude because larger bodies stay warmer in cooler temperatures.

Allen’s Rule

A biogeographical rule stating that mammals and birds living in cold areas have shorter appendages compared to their close relatives.

Gloger’s Rule

A biogeographical rule stating that pelage colors are darker in humid areas than in drier areas.

Mayr’s Rule

A biogeographical rule stating that populations in warm areas have less underfur and shorter guard hairs, and that litter sizes are higher in cooler climates.

Latitudinal Gradient

A global ecological pattern where species diversity decreases from the equator toward the poles, with marine mammals showing the opposite trend.

Elevation Gradients

Patterns in community composition and diversity showing that species diversity decreases as elevation increases due to decreased productivity and lower area.