Biogeography Flashcards
What is biogeography?
The study of geographic distributions of organisms over space and time
What does biogeography attempt to explain?
Why species and higher taxa are distributed the way they are, and why the biota from one place to another varies
What is historical biogeography?
The historical changes in an organisms distribution, including the changes that affect their current distribution
What is ecological biogeography?
Examines the current factors that affect the present distribution
What is an endemic species?
Species that is restricted to a specific region or locality and is found nowhere else
What is dispersal?
Extension of the geographic range of an species by the movement of individuals
What is vicariance?
Separation of a continuously distributed ancestral species into separate populations due to geographic or ecological barriers
What are the biogeographic realms?
Large spatial regions based on similarities in distribution and uniformity of biota composition. More similarities within regions than between regions
Why do distantly related groups end up with similar characteristics when isolated on continents?
Convergence, they were forced through similar environmental characteristics
What was the climate like during the Pleistocene?
Went through ice ages. Glaciation started in the Pliocene and reached it’s peak 100 000 years ago
What happened to the sea level during the Pleistocene?
Dropped as much as 100 metres because the water was being locked up in ice
Why was the Bering Land Bridge important?
It was a tundra covered plain between Siberia and Alaska , which allowed for the migration of animals to north America, including humans
What went extinct in the late Pleistocene extinction?
Megafauna, large mammalian species happened 11 000 years ago
What are the 3 possible mechanisms for the late Pleistocene extinction?
- Anthropogenic: humans hunted them to extinction
- Environmental: rapid warming changed the ecosystems of North America and larger species are more vulnerable to that
- Hyper-disease: humans brought their pets over and brought new diseases that the local fauna had no immunity to
What caused the late Pleistocene extinction?
Mainly climate change in the northern hemisphere and mainly humans in the southern hemisphere
What is Wallace’s line?
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
How can the rates of dispersal vary with plants?
How the seeds are spread. Wind-dispersed seeds spread faster than animal dispersed seeds
What are refugia?
Places in glaciated areas that weren’t covered in ice, so the populations of organisms there were able to survive
What sort of mechanism can explain a disjunct distribution of a species?
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
How can we determine if a disjunct distribution is due to vicariance or dispersal?
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
Is the distribution of the crickets on the islands of Hawaii due to vicariance or dispersal?
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
How and when did the landmasses of Gondwana break up?
- 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
Which Gondwanan land masses broke apart 135 million years ago?
India and Madagascar break apart from Australia and New Zealand
Which Gondwanan land masses broke apart 100 million years ago?
South America and Africa break apart
Which Gondwanan land masses broke apart 88 million years ago?
Madagascar and India break apart
Which Gondwanan land masses broke apart 35 million years ago?
South America and Antartica break apart
Is the distribution of the lemurs on Madagascar the result of vicariance or dispersal?
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
Is the distribution of the cichlid fishes the result of vicariance or dispersal?
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
Is the distribution of the tiger chameleons the result of vicariance or dispersal?
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
Is the distribution of the rattite birds the result of vicariance or dispersal?
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
