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Lecture 5Biogeography and Zoogeography

&Guest Presentation by Dr. Kris Hundertmark

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Biogeography = The study of the patterns of distribution of organisms, including both extant and extinct species.

Zoogeography = The study of these distributions in animals, including mammals

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Why are marsupials in only in Australia and the Americas?

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Why aren’t non-human primates in North America?

Or maybe they are?

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How has an individual species distribution changed, and why?

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Categories of Biogeography• Historical biogeography

– emphasizes the study of changes in species ranges that have taken place over evolutionay time.

• Ecological biogeography – spatial investigation of current distributions and seeks to explain that interaction in terms of community-level interactions.

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Distribution of Rangifer tarandus

CIRCUMBOREAL AND CIRCUMPOLAR

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Historical biogeography• Endemism – restriction of a species range to a

circumscribed area.

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Southeast Alaska

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Faunal Regions

Based on geographic barriers, geological history, and mammal distribution

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Plate tectonics & Continental drift

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Palearctic

Families = 42

Endemics = 0

Most species diversity is in the warm wet areas which the palearctic shares with the Ethiopean and Oriental.

Bering land bridge? 50% of the species in P are in Nearctic

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Nearctic

Families = 37

Endemics = 2

Antilocapridae Aplodontidae

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Neotropical

Families = 50

Endemics = 22

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Ethiopian

Families = 52

Endemics = 20

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Oriental

Families = 50

Endemics = 5

Colugos, tree shrews, hog-nosed bats, gibbons, and tarsiers

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Australian

Families = 28

Endemics = 20 (71%)

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Oceanic

Mammals that live on islands remote from continents and those that are fully marine

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Abiotic ProcessesContinental Drift

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Abiotic ProcessesIce Ages

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Abiotic ProcessesLess Severe Climate Change Still Matters

• Tipping points – a change of just a few degrees changes everything

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Biotic Processes

• Dispersal – can increase species richness– Ecological dispersal

• An individual moving from its natal area to breed elsewhere.

– Species dispersal (biogeographic term)• Passive – hitches a ride• Active – species move by there own locomotion

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Biotic processes

• Extinction (global) or Extirpation (local) = reduces species richness– Background – incidental loss due to local

factors (habitat change, competition, predation).

– Mass extinction – catastrophic event

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Local extirpations

• http://www.youtube.com/watch?v=I9skxcC2MYg

• http://www.wolfsongalaska.org/news/Alaska_current_events_205.htm

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Ecogeographic Patterns

• Island Rule• Rapoport’s Rule• Bergmann’s Rule• Allen’s Rule• Gloger’s Rule• Other Patterns

– Latitudinal and Elevation Gradients

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The term “RULE” is used in the loosest sense. There are exceptions in every case and these “RULES” often overgeneralize.

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Island rules

• Small mammals are bigger (insular gigantism)• Larger mammals are smaller (insular

dwarfism)• If food is scarce and you're small, for example,

getting bigger can help you travel farther for food and survive longer without eating. If food is scarce and you're large, on the other hand, getting smaller can help you survive on less food.

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Rapoport’s Rule

• Species ranges in mammals tends to increase from the equator to the poles

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Bergmann’s Rule

• Body size increases with latitude

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Allen’s rule

• Animals in colder climates have shorter appendages than their close relatives in warmer climates.– Endothermy?– Overgeneralized?

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Gloger’s rule

• Mammals with darker colored pelage are in more humid environments.– Humidity?– Snow, ice, and sand

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Latitudinal

• Species diversity decreases with increasing latitude.

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Elevation

• Decrease in species diversity with increase in elevation.