Module 2: Population Spatial Structure

If habitats are often patchy in distribution, thus?

populations distributions are often patchy

What is a classical meta population?

A group of populations in habitat patches, with each population demonstrating independent dynamics, but with some dispersal between patches

What does a classical meta population allow?

Recolonizing of a population from remaining occupied patches from a population that was extirpated.

What verbiage did Richard Levins use as opposed to meta populations?

Demes

What idea was Richard Levins the origin of?

A model used to describe population dynamics of insect pests across agricultural fields

What should large patches hold?

larger populations

What should large patches have?

higher immigration and emigration rates (its more likely to find a larger island than a smaller island)

Populations in larger patches should what?

persist longer than those in smaller patches (less extinction prone)

What matters between patches?

Distance matters

What defines different types of population structures

The amount of dispersal

What model are Bighorn Sheep thought to fit?

a classical meta population

What is the dispersal of bighorn sheep affected by?

Distance, Topography, and Barriers

What is distance in terms of bighorn sheep dispersal?

how far from patch to patch

Why does topography affect of bighorn sheep dispersal?

Sheep won’t cross valleys or long distances

What are barriers in terms of bighorn sheep dispersal?

Highway barriers and fences

In addition to overall loss of habitat, what are the effects of habitat fragmentation? (6)

1. Increase in the number of patches

2. Decrease in patch size

3. Increase in patch isolation

4. Greater isolation of individuals and populations (greater population structure)

5. Smaller populations (and associated negative effects)

6. Greater edge effects

What are estimates of migrants per generation (Nm) based on in desert bighorn sheep?

genetic difference and geographic distance of population