Lecture 6: Dispersal and Habitat Selection.docx

4 Pages
Unlock Document

Ecology, Evolution and Natural Resources

Dispersal and Habitat Selection Wednesday, October 30, 2013 9:27 AM I. Ultimate Causes of X --> Y a. Most dispersal is of young males, like lions and elephants b. Natal dispersion is opposite of natal philopatry c. Costs of Philopatry i. Inbreeding 1. Increases risk of progeny homozygous for recessive alleles 2. Incest taboo a. E.g. Voles i. In an experiment, when voles are placed with siblings, they leave earlier and disperse farther ii. In another experiment, when placed in a group of non-relatives, leave later and don’t disperse far b. E.g. German female cockroach i. Knows to not select related male to mate with 3. Recall Westermarck effect a. When two organisms cohabit for the first 6 years with someone of opposite sex, will not mate ii. Density-dependent competition 1. E.g. red worms in mice intestines a. When the density of red worm eggs increases, population will decrease 2. E.g. Springtails a. High density - higher dispersal rates b. Low density - lower dispersal rates iii. Reproductive suppression 1. Of animals that didn't disperse, by the older animals of the population a. Insects have chemical means b. Aggression c. Naked mole rats have large colonies and most of the young never breed d. Natal dispersers clearly WIN i. Avoid inbreeding depression and density dependent competition e. Sometimes, mother will disperse the babies i. Wolf spider 1. Sits and waits for ambushers 2. Disperses spiderlings over 185 hours - assume that this increases their survival and her fitness/R.S. 3. Goes all over- clearly a large time and effort investment f. Costs of Natal Dispersion i. Costs Lots of Energy 1. e.g. Cricket a. Has two morphs i. Disperser morph: big wings and big thoracic muscles 1. Graph: produce eggs with a delay 2. Larva are more likely to survive ii. Non-disperser morph: stubby wings and no thoracic muscles 1. Produce more eggs 2. Graph: produce eggs right away 3. Larva less likely to survive ii. Increased Predation Risk 1. Fossorial species are small animals that live underground a. To disperse, they come aboveground and there are hawks and owls in their paths iii. Harsh Weather 1. Most dispersion occurs in the spring, and so bad weather iv. Fact: approximately 50% of dispersers are unsuccessful II. Proximate Mechanism of X --> Y a. Natal Dispersion i. Comparison search: visits several areas, revisiting some, then
More Less

Related notes for 11:216:115

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.