Small Populations

Question 1

Describe the effects of an extinction vortex

Answer 1

Small pop.s are vulnerable to positive feedback loops, ie. extinction vortex

• small pop. > inbreeding, genetic drift, loss of genetic variability, decline in idnv, fitness + pop. adaptability > lower reproduction, higher mortality > smaller pop.

Question 2

What is the allee affect? Possible reasons?

Answer 2

Positive density dependence. Recruitment is higher when density is higher (to a point!! then there’s a crash)

Could be a result of social behavior

Question 3

Why are many species uncommon?

Answer 3

• geographic size range (smaller range = fewer indv.)
• body size (generally bigger orgs. = smaller pop/lower density)
• home range (bigger home range = lower density)
• degree of specialization (can be locally common where specific needs are met)
• trophic level (higher trophic level = more rare typically)

Question 4

How is the Minimum Viable Population concept applied to conservation?

Answer 4

The smallest population that can sustain itself over a certain amount of time, determined by PVA

Question 5

What are some reasons a population might reach it’s allee threshold?

Answer 5

• genetic affects
• social breakdown (shared vigilance etc.)
• inability to find a mate

Question 6

What is the effective population size?

Answer 6

The amount of population that contributes to the gene pool. Always smaller than actual pop. because of poor health, sterility, density/dispersal, and most males never breed