topic 9: biogeography what is biogeography?

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Topic 9: Biogeography

� What is biogeography?

� What are the different disciplines of biogeography?

� What are important concepts in biogeography?

� Herpetological examples

What is biogeography?

� Study of past and present ___________, ___________ and _______ of organisms

� Based on premise that history of _______ and _____________ are interconnected

� Addressing why organisms have the patterns of distribution that they have

What is biogeography?

Biogeographic

Distribution

HistoryEcology

Organism Environment Vicariance Dispersal

Phylogeny

All of these nested factors influence the distribution and abundance

of organisms, either directly or indirectly

What are the four disciplines of biogeography?

� __________ biogeography



� _____________________

� Each of these focuses on different factors that influence distribution and abundance

� Each has something to say about why Amphisbaenidae are distributed

Pough et al. 2004, Fig. 4-22

� ___________ biogeography� How distributions have

been shaped by organismal biology

� ___________ biogeography� How presence/absence and

diversity are determined on islands

� ___________ biogeography� How distributions have

been shaped by the Earth’s history

� Phylogeography� Next lecture

� Important considerations when studying frog distributions� Pipidae� Pelobatidae� Megophrydae



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� How would these distributions have come about?

Pough et al. 2004, Fig. 3-27Pough et al. 2004, Fig. 4-22

Amphisbaenidae

Pipidae MegophrydaePelobatidae


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Ecological biogeography - Concepts

� How distributions have been shaped by organismal biology

� Physiological tolerances

� _______________ biology

� Moisture

� _______________

� Altitude

� ______________________

Miller 2003, Ricklefs 2000


� Agreeable places for a species to live can change through time

� Long term

� ___________

� ___________

� Short term

� ______________

� ______________


� How distributions have been shaped by organismal biology

� Niche characteristics

� __________________

� Terrestrial

� __________________

� Aquatic

� __________________

Powell and Russell, 1992

© J. Losos

© Auburn

Herp Soc

Twig giant

Crown giant

Trunk-crown

Trunk-crown dwarf

Trunk-ground© Reptilien-

Center.de

© KP Bergmann

Ecological biogeography - Example

� Interspecific competition

� Availability of niches

� Availability of resources

Duellman & Pianka, 1990

� Geckos & frogs fill similar niches

� Both are mainly nocturnal

� Diverse in the tropics

Thecadactylus


� Pattern is pronounced all over the world

Duellman & Pianka, 1990

� Geckos & frogs fill similar niches

� Both feed on small insects


� _______________

� Some species are better than others

� Leathery vs. hard eggs

� Starvation resistance

� Some move further than others

� Chance…

Censky et al. 1998; Photos PJB, KP Bergmann

Iguana iguana

introduced to Anguilla by

hurricane

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� Elevational distributions of hylid frogs in Oaxaca

� Considerable ________________ changes with __________

� Most diverse at mid-elevation

Pough et al. 2004, Fig 5-20

� Pond breeders at low elevations

� Stream breeders at mid-elevations

� Bromeliads used on Atlantic slopes – more moist

Island biogeography - Concepts

� How presence/absence and diversity are determined on islands

� Important island factors

� _______________________

� Proximity to _____________

� Important processes

� _____________

� _____________

Photo © PJB


� Important island factors

� Size

� Proximity to mainland

� Important processes

� Immigration

� Extinction

� # of Species

� ______________ with increased island area

� ______________ with increased distance from mainland

Government of Canada


� Important island factors� Size� Proximity to mainland

� Important processes� Immigration� Extinction

� With increased # of species� _____________ decreases� _____________ increases

� Results in equilibrium

� Large, near islands have� __________ extinction rate� ________ immigration rate� __________species

# of SpeciesRate of Immigration/Extinction

Equilibrium

I ENear

SmallNearNearNear

SmallSmallSmall

Equilibrium

I EI E

# of Species

I E

Rate of Immigration/Extinction

# of Species

I E

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Island biogeography

- Example

� Isolation by distance

� Faunal similarity

� Closer islands have more species in common

� Differences between frogs and snakes

� ____________________

� ____________________

� ____________________

� Ecological biogeography is also important…


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Island biogeography

� Not all islands are surrounded by water!

� Island biogeography applies to suitable patches of habitat

� Habitat surrounded by obstacles/”bad” habitat

� Examples:

� Reefs

� __________________

� Oases of various kinds

� __________________

© J Palkiewicz; www.birddigiscoper.com

Historical biogeography - Concepts

� How distributions have been shaped by the Earth’s history

� Changes in ___________

� Changes in ______________

� _________________

Pough et al. 2004, Fig 5-3b

• Much of Mesozoic (251-65 mya)

• Forested•Warm

•Home to many animals

including reptiles

Antarctica’s climate has

changed considerably over

millions of years


� Changes in sea level


• Land masses become connected…

•…or they become disconnected


� ___________________

� Fundamental force behind many changes

� Huge driver of biogeographic patterns

� The continents move!!!

Campbell 1993

� Continents are on tectonic plates

� Compose the crust

� Float on the mantle

� Spread apart

� Collide


Zug et al. 2001, Fig 13.15

� Pangea �

� Laurasia

� Nearctic

� Palearctic

� Oriental*

� Gondwana

� Neotropical

� Ethiopian

� Australian

� Oriental*


� _____________ & ____________

� Two major mechanisms behind patterns of distribution

� Competing theories

� Both clearly important

� Much past controversy

Pough et al. 2004, Fig 5-1b

T1

T2

T3

Vicariance

Vicariance

Dispersal

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� _______________� The separation of a group

of organisms by a geographic ____________

� A barrier becomes erected, splitting a population

� Separated populations __________________

� Many possible vicariant agents:

� Plate tectonics

� ___________________� Rivers changing course� ___________________

� Canyon building, etc.

© Google, PJB


� Vicariance

� Example: Distribution of the Amphisbaenidae

� Multiple vicariant events giving modern distribution


1. Break up of ____________

2. Eastern movement of

____________ plate

3. Drying of _____

_____________


� _____________

� The permanent movement of organisms from one geographic location to another

� Hard to test for, but clearly important

� Many dispersal agents:

� Some organisms move

� ____________________

� Ocean currents & rivers

� ____________________

� Humans

Censky et al. 1998


� “Lizards took Express Trail to Polynesia”

� Lipinia noctua (Scincidae)

� Low mtDNA divergence among Polynesian populations

� __________-mediated dispersal

Austin, 1999


� Dispersal is only way that anything gets on __________ islands…

� Galapagos, Hawaii, Lesser Antilles, Krakatoa (natural experiment)

� Ocean currents can play a big role

� Also dispersal ability of organisms


Historical biogeography - Example

� The Caribbean has a complex history


� Heated debate about roles of vicariance and dispersal

� Only when V is disproven, can you suggest D?

� How might we distinguish V & D?

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Historical biogeography - Example� Look at timing of phylogenetic

divergences

� Dated divergences between species on different landmasses

Hedges et al. 1992

� Distinct times when vicariance possible, otherwise dispersal

� Anolis, Eleutherodactylus,

Sphaerodactylus


� Explaining a disjunct distribution pattern

� South America + Madagascar, but not Africa

Noonan & Chippindale 2006

� Malagasy Oplurinae are nested within the New World Iguanidae

� Why aren’t Iguanids in Africa?


� Explaining a disjunct distribution pattern

� South America + Madagascar, but not Africa


Similar pattern in:

• Boinae

• Podocnemidae


� Madagascar was more closely associated with ____________________ (and India) than Africa

� Not complete picture

� Why aren’t these herps in India?

� Fossil Boid Madtsoia has been found all over Gondwana

� Perhaps climate change and competition played a role



� Climate: Africa has undergone considerable drying, but there are still wet areas, without these animals

� Competition: Ecologically analogous taxa exist


� “Agamidae” and Pythoninae have similar ranges �

� Origin in SE Asia with dispersal into Africa & Australia…

“Agamidae”

topic 9: biogeography what is biogeography?

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