Biogeography

Question 1

What is biogeography?

Answer 1

The study of geographic distributions of organisms over space and time

Question 2

What does biogeography attempt to explain?

Answer 2

Why species and higher taxa are distributed the way they are, and why the biota from one place to another varies

Question 3

What is historical biogeography?

Answer 3

The historical changes in an organisms distribution, including the changes that affect their current distribution

Question 4

What is ecological biogeography?

Answer 4

Examines the current factors that affect the present distribution

Question 5

What is an endemic species?

Answer 5

Species that is restricted to a specific region or locality and is found nowhere else

Question 6

What is dispersal?

Answer 6

Extension of the geographic range of an species by the movement of individuals

Question 7

What is vicariance?

Answer 7

Separation of a continuously distributed ancestral species into separate populations due to geographic or ecological barriers

Question 8

What are the biogeographic realms?

Answer 8

Large spatial regions based on similarities in distribution and uniformity of biota composition. More similarities within regions than between regions

Question 9

Why do distantly related groups end up with similar characteristics when isolated on continents?

Answer 9

Convergence, they were forced through similar environmental characteristics

Question 10

What was the climate like during the Pleistocene?

Answer 10

Went through ice ages. Glaciation started in the Pliocene and reached it’s peak 100 000 years ago

Question 11

What happened to the sea level during the Pleistocene?

Answer 11

Dropped as much as 100 metres because the water was being locked up in ice

Question 12

Why was the Bering Land Bridge important?

Answer 12

It was a tundra covered plain between Siberia and Alaska , which allowed for the migration of animals to north America, including humans

Question 13

What went extinct in the late Pleistocene extinction?

Answer 13

Megafauna, large mammalian species happened 11 000 years ago

Question 14

What are the 3 possible mechanisms for the late Pleistocene extinction?

Answer 14

1. Anthropogenic: humans hunted them to extinction
2. Environmental: rapid warming changed the ecosystems of North America and larger species are more vulnerable to that
3. Hyper-disease: humans brought their pets over and brought new diseases that the local fauna had no immunity to

Question 15

What caused the late Pleistocene extinction?

Answer 15

Mainly climate change in the northern hemisphere and mainly humans in the southern hemisphere

Question 16

What is Wallace’s line?

Answer 16

Line in South-east Asia devised by Wallace. Species on the left side of the line are closely related to species found in Asia, and species on the right side of the line are closely related to species found in Australia and New Guinea

Question 17

How can the rates of dispersal vary with plants?

Answer 17

How the seeds are spread. Wind-dispersed seeds spread faster than animal dispersed seeds

Question 18

What are refugia?

Answer 18

Places in glaciated areas that weren’t covered in ice, so the populations of organisms there were able to survive

Question 19

What sort of mechanism can explain a disjunct distribution of a species?

Answer 19

Can be explained by vicariance, when one continuous population got fragmented and only the populations in refugia survived. However, can also be explained by dispersal

Question 20

How can we determine if a disjunct distribution is due to vicariance or dispersal?

Answer 20

Compare area cladograms to species cladograms. If they match up, the population was likely fragmented by geographic barriers. If they don’t, that provides more evidence for dispersal

Question 21

Is the distribution of the crickets on the islands of Hawaii due to vicariance or dispersal?

Answer 21

Dispersal. The crickets on Kawaii (the oldest island) are the oldest, then they dispersed to Oahu when the island appeared and eventually became a new species. They did this again when the islands of Maui and Hawaii appeared

Question 22

How and when did the landmasses of Gondwana break up?

Answer 22

• 170 million years ago in the Triassic, were one large landmass
• 162 million years ago a split appeared down the middle, with Africa and South America on one side and Australia, New Zealand, India, and Madagascar on the other
• 135 million years ago India and Madagascar break apart from New Zealand and Australia
• 100 million years ago South America and Africa break apart
• 88 million years ago India and Madagascar break apart
• 60 million years ago India is going further north
• 55 million years ago India hits the Asian plate
• 35 million years ago South America and Antartica break apart

Question 23

Which Gondwanan land masses broke apart 135 million years ago?

Answer 23

India and Madagascar break apart from Australia and New Zealand

Question 24

Which Gondwanan land masses broke apart 100 million years ago?

Answer 24

South America and Africa break apart

Question 25

Which Gondwanan land masses broke apart 88 million years ago?

Answer 25

Madagascar and India break apart

Question 26

Which Gondwanan land masses broke apart 35 million years ago?

Answer 26

South America and Antartica break apart

Question 27

Is the distribution of the lemurs on Madagascar the result of vicariance or dispersal?

Answer 27

Dispersal. They came from African and Asian lineages, and the first lemur appeared on Madagascar no earlier than 62 million years ago. Madagascar broke apart from India 88 million years ago, but the lemurs weren’t there. Instead, they dispersed to Madagascar 62 million years ago

Question 28

Is the distribution of the cichlid fishes the result of vicariance or dispersal?

Answer 28

Vicariance. The species found in Africa are the sister group of species found in South America, and the species found in Madagascar are the sister group of the species found in India

Question 29

Is the distribution of the tiger chameleons the result of vicariance or dispersal?

Answer 29

Dispersal. Most species are found in Madagascar, but one species is closely related to the species found in the Seychelles islands near Australia. The only reason that one can be there is dispersal

Question 30

Is the distribution of the rattite birds the result of vicariance or dispersal?

Answer 30

Dispersal. The species found in South America are closely related to the species found on New Zealand, which doesn’t match up with the breakup of the continents