Habitat Issues

Question 1

What is a sink and trap? How do they differ?

Answer 1

Both are likely to be patches that also have low reproductive success.

Sinks: natural, but can be made worse by humans. are avoided by orgs. and chosen in absence of better habitat
Traps: a sink that is preferred by an org. can be caused by quickly changing conditions

Question 2

How can fragments negatively affect populations?

Answer 2

• can create traps, eg. bird mortality is higher in fragmented vs. contiguous forest (more edge space, often surrounded with human-subsidized predators)
• can fragment populations and cause genetic problems, eg. ocelots in texas

Question 3

Do fragments affect populations right away?

Answer 3

NO. Relaxation takes time, and can be faster or slower depending on factors (eg. size/isolation of the fragment, dispersal ability, home ranges, etc.) When relaxation is complete we say the extinction debt has been paid.

Question 4

Explain how roads create habitat fragments

Answer 4

• can lead to reduced gene flow between populations and increase drift/inbreeding.
• more major roads have bigger impacts, fixation tends to be higher around major roads
• can reduce heterozygosity

Question 5

How does road mortality affect populations?

Answer 5

Beyond losses they can bias populations, eg. female turtles die more often on roads looking for nesting areas, leading to male-biased pop.s near roads

Question 6

Explain the tragedy of the commons

Answer 6

Unregulated environments can be exploited disproportionately by an individual or group but the cost is shared equally.

Question 7

What is introgression? What are it’s effects and how can it be problematic?

Answer 7

The transfer of genetic information from one species to another as a result of hybridization between them and repeated backcrossing.

Can cause allelic decline as one species becomes more common, eg. blue and golden-winged warblers