From Biol301

• Notes generously supplied by Alice.

Contents 1 Distribution Outside or Within the range 1.1 Models of Dispersal 1.1.1 Diffusion: a gradual spread of a pop. Across hospitable habitat 1.1.2 Jump Dispersal 1.1.3 Secular Dispersal 1.2 Dispersal may not be the only factor limiting distribution 1.2.1 Predation 1.2.2 Physical Conditions

Distribution Outside or Within the range

• Species are absent because

1. Dispersion
2. Behavior
3. Other Species
4. Physical Barrier

Models of Dispersal

Diffusion: a gradual spread of a pop. Across hospitable habitat

Jump Dispersal

• found mostly in islands
• ex. Fruit fly and then produce new species (best ex. b/c they have make like 100s of different species
• ex. Human introduction
• ex. Starlings- brought over by humans to Central Park and now they are all over the US

Secular Dispersal

• a diffusion over time results in genetic divergence of peripheral pop. from ancestral populations.
• salamander
• are found in a whole range of mts, but are different species
• adjacent species do interbreed

Dispersal may not be the only factor limiting distribution

• ex. Habitat selection
  • mesquitos and where they lay their eggs…..can’t do dance = no egg

Predation

• ex. Guam
  • introduction of the brown tree snake
  • now it’s everywhere, and caused the extinction of many birds, mammals, and lizards.

Physical Conditions

• ex. Hardwood trees and fires
• some trees can live through fires

PLEASE CHECK THE NOTES FOR THE LAST THREE SUBJECTS BECAUSE THEY ARE INCOMPLETE!