BIO464 Lecture 3: Factors Affecting Distribution & Abundance: Dispersal

VOCABULARY flashcards covering the concepts of ecological dispersal modes, colonization processes, and Lidicker’s hypothesis based on the BIO464 lecture.

Dispersal

The ecological process involving the movement of individuals away from their place of birth to colonize new areas, affecting distribution and population density.

Gene flow

The outcome of successful dispersal and colonization that impacts the genetic structure of a population and Darwinian fitness.

Gypsy Moth (Lymantria dispar)

An introduced species intended for the silk industry that escaped and destroyed timber trees, now managed using pheromone traps.

Chestnut blight fungus (Cryphonectria parasitica)

An Asian fungus that arrived in the late $19^{\text{th}}$ century and eliminated the American chestnut tree (Castanea dentata) above-ground biomass in only $40$ years.

Diffusion

A mode of dispersal involving gradual or slow movement across hospitable terrains over several generations, seen in Sea otters and Gypsy moths.

Jump Dispersal

A quick movement of individuals across large distances and usually unsuitable terrain within a single life span, such as island colonization.

Secular Dispersal

A very slow dispersal process occurring over geologic time that commonly involves evolutionary changes in the dispersing populations.

Ruffed grouse (Bonasa umbellus)

A bird found only on islands $800\,\text{m}$ or closer to the mainland because they cannot fly further over water, which acts as a barrier.

Heterogeneity

The state of genetic diversity in offspring that is increased by dispersers mating with new individuals, reducing in-breeding and increasing fitness.

Krakatau

A volcanic island where an eruption in $1883$ caused total extinction, followed by colonization starting with a single spider after $9$ months.

Fugitive Species

Weed-like organisms, such as dandelions or water boatmen, that devote most effort to dispersal and colonize temporary or disturbed habitats.

Taraxacum officinale

A fugitive weedy species adapted for long-distance dispersal by wind or animals.

Lidicker’s Hypothesis

A theory explaining dispersal through two main types: presaturation dispersal and saturation dispersal.

Presaturation Dispersal

Dispersal during the population increase phase where fit individuals of any sex or age group leave before resources are depleted.

Saturation Dispersal

Dispersal occurring when a population exceeds carrying capacity, involving mostly unfit juveniles with low survival chances.

Source and Sink

The two requirements for dispersal, where the sink is a vacant, marginal, or unsuitable habitat.