Concept 53.5: Density-Dependent Regulation and Metapopulations

Vocabulary flashcards covering the key terms and definitions related to density-dependent factors, population regulation, and metapopulation concepts from the lecture notes.

Density-dependent factor

A factor whose impact on birth or death rates increases with population density, helping regulate population size.

Density-independent factor

A factor whose impact on birth or death rates does not vary with population density.

Equilibrium density (Q)

The population density at which birth and death rates are equal, so the population remains constant without immigration or emigration.

Density-dependent reproduction

Reproduction rate declines as population density increases, often because resources become scarcer.

Density-dependent mortality

Death rate increases with population density.

Density-independent mortality

Death rate determined by factors such as drought or temperature, independent of density.

Immigration

Arrival of individuals from outside the population into the local population.

Emigration

Departure of individuals from the population to other areas.

Negative feedback

A regulatory response where increasing density reduces population growth, preventing unbounded growth.

Population regulation

Process by which density-dependent factors cause population size to decrease when large or increase when small.

Competition for resources

Rising density intensifies competition for nutrients and resources, reducing reproductive rates.

Disease transmission (density dependent)

Transmission rate of disease increases as population becomes more crowded, increasing mortality or reducing reproduction.

Predation (density-dependent regulation)

Predation can increase with prey density, contributing to density-dependent mortality.

Territoriality

Competition for space by territorial behavior that limits population density.

Intrinsic factors

Internal physiological factors that regulate population size, such as hormonal changes delaying maturation.

Toxic wastes

Toxins produced in or by the population (e.g., ethanol in yeast) that reduce population growth.

Population dynamics

Fluctuations in population size over time due to births, deaths, immigration, and emigration.

Population cycles

Regular boom-and-bust fluctuations in populations (e.g., hare-lynx cycles ~10 years).

Snowshoe hare

Small herbivore with ~10-year population cycles in northern forests, influenced by predation and food availability.

Lynx

Predator of snowshoe hare; lynx populations tend to rise and fall with hare cycles.

Metapopulation

A network of discrete habitat patches linked by dispersal; local extinctions and recolonizations occur.

Glanville fritillary (Melitaea cinxia)

Butterfly whose populations form a metapopulation across patches; dispersal is affected by Pgi genotype.

Pgi gene (phosphoglucoisomerase)

Gene that codes an enzyme; variation affects dispersal ability and metabolism, influencing metapopulation dynamics.

Patch occupancy

The presence or absence of populations in habitat patches at a given time.

Isle Royale moose-wolf dynamics

Predator-prey fluctuations where harsh winters, predation, and food availability drive cycles in moose and wolf populations.