Con Bio Exam 2

heterozygosity (H)

proportion (%) of genes the average individual is heterozygous or proportion of heterozygous individuals in a population

Population Divergence (Dpt)

is a measure of genetic differentiation between populations of the same species.

Path Analysis Technique

• calculates inbreeding coefficient (Fx) X represents individual of interest

• draw the pedigree so that any common ancestors appear only one.

• a common ancestor is any individual related to both parents of the individual of concern (X)

  • if there are no common ancestors, then Fx=0 and X is noninbred

Island Types

Temporary (MS River sandbars), Continental (MS Gulf islands), Oceanic (Caribbean)

Island colonization factors

1. island size

2. distance to mainland and/or source of colonists

3. latitude

4. topography

5. disturbance regime (i.e. Caribbean hurricane alley)

Adaptive space

provided by isolation may promote appearance of dwarfism and gigantism

Rescue Effect

Reduction in extinction rate of near islands versus distant ones (an ecological phenomenon where immigration from larger, more stable populations helps sustain smaller, isolated populations that might otherwise face extinction.)

Target Effect

• Increase in immigration rate on large islands versus small ones.

• the idea that larger habitats or "targets," such as large islands or extensive habitat patches, are more likely to be colonized by new species compared to smaller habitats.

Adaptive Radiation

evolution of ecologically diverse species from an ancestral colonizer to island and/or island group. (Species arising from radiation fill different available ecological niches)

Ecological Release

in the absence of competition and/or predation, island species expand into a greater variety of habitats compared to closely related mainland species. (Niche width of species expands due to relaxed competition)

Density Compensation

compared with conspecific mainland populations, species on oceanic islands exhibit relatively greater densities.

Metapopulations

a balance between extinction rates in occupied patches and the colonization rate of empty patches.

a group of separate populations of the same species that interact with each other by means of individuals moving between them.

Extinction

Constant (risk) multiplied times number of occupied patches

Colonization

Dependent on number of occupied (sources) and empty (targets) patches

Turnover

Extinction of local populations and establishment of new local populations in empty habitat patches by migrants from existing local populations

General metapopulation “Levins metapopulation”

Large network of similar-size small patches– Local patch dynamics occur at faster time scale than metapopulation dynamics– Sometimes used to describe system where all local populations have a high risk of extinction

Mainland-island metapopulation “Boorman-Levitt metapopulation”

Set of patches (“islands”) within dispersal distance from large patch (‘mainland’) population that never goes extinct– Metapopulation persists only if ‘mainland’ patch persists

Source-sink metapopulation

Subpopulations with negative growth rates (in absence of dispersal) at low population numbers– Source patches generate dispersers

Non-equilibrium metapopulation

-Long-term extinction rates exceed colonization

– Extreme case isolation among subpopulations is so that dispersal (and hence recolonization) is precluded