Biogeography

– the study of organismal distribution in

evolutionary, phylogenetic, or ecological

contexts

Current organismal distributions result from

both evolutionary history and contemporary

ecology

Biogeographic Realms of the World (differences exist among authors)

http://biology.clc.uc.edu/courses/bio303/terrest_habitats.htm

Definitions

Indigenous – native to an area

Endemic – unique to an area

Sympatric – overlapping geographic distribution (i.e,

two species living in the same place)

Parapatric – contiguous but non-overlapping

geographic distribution

Allopatric – non-overlapping geographic distribution

Disjunct endemism – nearest relatives in allopatry,

typically separated by a geophysical barrier

alternative hypotheses to account for disjunct

endemism:

Vicariance – barrier divides originally contiguous

population into two or more

Dispersal – organisms overcome barrier (either

actively or passively) to establish new population

Organismal distributions result from both

contemporary ecology and evolutionary

history

Ecological factors:

Resource availability, competitors, abiotic

factors (e.g., climate), environmental

heterogeneity

Similar patterns of diversification in

different locations (e.g., community

convergence or parallel radiations) is

evidence of common ecological factors

Historical processes:

Phylogeny, vicariance, dispersal, extinction

Similar phylogenetic topologies among

unrelated clades is evidence of common

causes of vicariance or modes of dispersal

Snapping shrimp (Alpheidae) - vicariance

Hawaiian Pohutukawa (Metrosideros) - dispersal

Percy et al 2008 Proc. R. Soc. B (2008) 275, 1479–1490

Dias dos Santos 2011 Pap. Avulsos Zool. 51

Vicariance and Dispersal

Models of Gene Flow

Island model – equal probability of flow

Stepping stone model – ordered

probability

Isolation by distance model – probability

inversely proportional to distance

Extinction and recolonization model –

stochastic replacement

Species Diversity

Rat

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Colo

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n R

ate of E

xtin

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nearby island

MacArthur and Wilson’s model of Island Biogeography

Species Diversity

Rat

e of

Colo

niz

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n R

ate of E

xtin

ction

distant island

MacArthur and Wilson’s model of Island Biogeography

Species Diversity

Rat

e of

Colo

niz

atio

n R

ate of E

xtin

ction

small island

MacArthur and Wilson’s model of Island Biogeography

Species Diversity

Rat

e of

Colo

niz

atio

n R

ate of E

xtin

ction

big island

MacArthur and Wilson’s model of Island Biogeography

Species Diversity

Rat

e of

Colo

niz

atio

n R

ate of E

xtin

ction

nearby island

distant island big island

small island

MacArthur and Wilson’s model of Island Biogeography

Community Convergence Parallelism in Theria:

Marsupials and Placentals

“Ecomorphs” of Carribean Anoles