Population Dynamics and Dispersal Mechanisms

Population

a group of the same species in the same area at the same point in time.

Population Dynamics

The continuous flux in population abundance and distribution over time.

ADD

immigration and birth

SUBTRACT

Emigration and death

r

b - d + i - e

Florida Panther

Lives in 5% of historic range, only cougar species in Eastern US, only 80-100 individuals left.

Conservation plan

Calling for a population of 240 individuals would require 8,000 to 12,000 sq miles, land wanted for development.

Dispersal

movement of organisms

Range Expansion

movement of individuals to establish populations in new areas, typically on the margins of their existing range.

Halophila stipulacea

A seagrass native to the Indian Ocean that has expanded its range extensively.

Dispersal within Population Range

Individuals move within the boundaries of their established population range.

Dispersal between Metapopulations

The distribution of populations across a landscape can create subpopulations.

Lag time

The delay in response of individuals moving within their established range.

Kestrels and Owls

Move in and out of sections of home range tracking vole densities.

Moose and Wolves

Moose move around to follow vegetation, and wolves follow moose.

Mini Ice-Age

A climatic condition from the 1600s to 1800s that affected species distribution.

Subpopulations

Typically large, self-sustaining, and have limited exchange between other subpopulations.

Metapopulation

Established when individuals from one subpopulation disperse/migrate between multiple subpopulations.

Benthic coverage

The extent of seagrass coverage on the ocean floor.

Caribbean

Region where Halophila stipulacea has expanded its range.

Indian Ocean/Red Sea

Original habitat of Halophila stipulacea.

Taal Lake

Formerly known as Taal Bay, referenced in the context of historical geographic changes.

1734 Murillo Velarde map

A historical map depicting Laguna de Taal.

Dispersal

The movement of individuals from smaller subpopulations to larger subpopulations.

Metapopulation

A group of spatially separated populations of the same species that interact through dispersal.

Gene flow

The transfer of genetic material between subpopulations, maintaining genetic diversity.

Source

A subpopulation that is often increasing in size and exports individuals to surrounding subpopulations.

Sink

A less suitable habitat with a non-self-sustaining populace that may go extinct without being rescued from source populations.

Buffer

A mechanism that protects a species from extinction by providing support during catastrophic events.

Doomed population

A population that is at risk of extinction due to unfavorable conditions.

Logistic growth model

A model describing how populations grow in a limited environment, reflecting the carrying capacity.

Patch occupancy (P)

The proportion of patches that are occupied by subpopulations.

dP/dt

The change of patch occupancy over time.

Patch colonization rate (c)

The rate at which empty patches are successfully colonized.

Patch extinction rate (e)

The probability of extinction of a patch.

Colonization rate formula

cP(1-P), representing the colonization rate of empty patches multiplied by the probability that a patch is vacant.

High P, high extinction rate

When the proportion of patches occupied (P) is very high, there will be a relatively high overall extinction rate.

Low P, low extinction rate

When the proportion of patches occupied (P) is very low, there will be a relatively low overall extinction rate.

Very high P, low colonization rate

When the proportion of patches occupied (P) is very high, the overall colonization rate will be relatively low due to very few empty patches to colonize.

Very low P, low colonization rate

When the proportion of patches occupied (P) is very low, the overall colonization rate will be relatively low due to very few colonizers to establish new subpopulations.

Intermediate P, high colonization rate

When the proportion of patches occupied (P) is intermediate, the overall colonization rate will be relatively high due to sufficient colonizers and sufficient open patches.

S.L.O.S.S.

An acronym for Single Large or Several Small, referring to a debate in conservation about the best approach to reserve design.

Island Biogeography

A theory that explores the relationship between island size and distance to the source of immigration versus extinction rate.

Jared Diamond's suggestion

He suggested that a single large reserve is better for preserving species than several small reserves of the same total area.

Habitat fragmentation

The loss of a species habitat and the partitioning of remnant patches, typically divided by some barrier.