Biogeography

Question 1

What does endemic mean?

Answer 1

restricted to a specific region or locality

Question 2

What is dispersal?

Answer 2

• extension of species geographic range by movement of individuals
• however, they NEVER return to the og location

Question 3

What is vicariance?

Answer 3

separation of a continuously distributed ancestral species into separate populations due to geographic or ecological barrier

Question 4

How does vicariance occur?

Answer 4

• when a single species is split into two groups due to a barrier/isolation, and a lack of gene flow between the two groups causes disjunction
• division of a formerly continuous range
• where a single species becomes 2 different distinct species

Question 5

How does Dispersal occur?

Answer 5

• when there is a single ancestral population, and a small group disperses and then becomes isolated.
• the original species is still there, but the isolated group will become a new species.
• extension of a species geographic range to an area not previously occupied

Question 6

What are the three mechanisms to explain the Late pleistocene extinction?

Answer 6

1. Anthropogenic causes (large species being hunted, over-hunting may have eliminated key-stone species)
2. Environmental changes (rapid climate change due to warming, lead to fundamental ecosystem changes)
3. Hyper-disease (New human migrants brought disease with them)

Question 7

What information do we need to explain geographic distribution of animals/splitting of lineages?

Answer 7

1. phylogeny of evolutionary relationships
2. age of divergences (from fossils or molecular clocks)
3. biogeographic distribution of taxa at different times

Question 8

What are the three hypotheses to explain why the highest species diversity occurs at the tropics?

Answer 8

1. ecological factors (Tropics can support more species)
2. net speciation rate (is higher in the tropics)
3. time and area effect (warm areas are older, glaciation is recent

Question 9

How can ecological factors lead to higher species diversity at the equator?

Answer 9

• tropical regions have higher tolerance to physical factors, and can support more species.
• greater productivity = more resources
• a reduction in overlap of species leads to less competition
• and more specialization of species leads to more complex food webs = more species `

Question 10

How can time and area effect lead to higher species diversity at the equator/tropics

Answer 10

• no glaciation periods to wipe out species and ‘reset’ the species number, so the tropics just continue to gain more species
• the lineages have been accumulating species for much longer in the tropics