1. Biogeography By
Michelle Cockrell

2. ASKS
Why is a species or higher taxonomic group confined to its present range?
What enables a species to live where it does, & what prevents it from colonizing other areas?
What role does geographic variation in climate, topography, & interactions with other organisms play in limiting the distribution of a species?
How do different kinds of organisms replace each other as we go up a mountain or move from a rocky shore to a sandy beach nearby?
How does a species come to be confined to its present range?
What are a species’ closest relatives, & where can they be found? Where did its ancestors live?

3. How have historical events – such as continental drift, Pleistocene glaciation, & recent climatic change – shaped a species’ distribution?
Why are animals and plants of large, isolated regions – such as Australia, New Caledonia, & Madagascar – so distinctive?
Why are some groups of closely related species confined to the same region, while others are found on opposite sides of the world?
Why are there so many more species in the tropics than at temperate or arctic latitudes?
How are isolated oceanic islands colonized, & why are there nearly always fewer species on islands than in the same kinds of habitats on continents?

4. Biogeography is:
The study of the distributions of organisms in space and time.
How does biological diversity vary over the surface of the Earth?
Attempts to ask and answer: Which? Where? How? Why? And Why Not?
Includes plant and animal species; in their past & present habitat, interim living sites, and/or survival locales

5. History
Aristotle – climate and geography determined an organism’s form
George-Louis LeClerk, Compte de Buffon –
1st to offer a method to explain distribution patterns
Organisms changed over time to get along with their environment
1st principle – environmentally similar but isolated regions have distinct assemblages of mammals & birds (Buffon’s Law)
Augustin Pyramus de Candolle –
beginnings of ecological and historical biogeography
Recognized limiting factor of competition & problem of dispersal
Phillip Lutley Schlater – each species created within & over the geographical area which it now occupies
Charles Darwin –
suggests that animals change to fill the niche available to them (finches)
Suggests that some of the differences between floras & faunas of the separate continents might have resulted from their having separate evolutionary histories.
Buffon (1766) – similar climates produce similar looking characteristics, not the same species. Division of old and new world. All created in old & crossed when old and new were joined.

6. History cont’d Alfred Russel Wallace –
created 6 biogeographic regions based on the congruent patterns of endemic species
Identified & commented on many aspects of biogeography that still occupy us today:
Effects of climate, extinctions, dispersal, competition, predation & adaptive radiation
Need to be knowledgeable about past & present faunas, fossils & stratigraphy
Distribution of organisms might indicate land connections
Regions included mammals, reptiles & insects. Regions: Nearctic, Neotropical, Palaeartic, Ethiopian, Oriental, Australian

7. History cont’d Alfred Lothar Wegener –
Proposed continents were once connected = Pangea
1912

8. History cont’d Leon Croizat – “Earth and life evolve together.”
Concept of a dynamic Earth evolving along with the organisms that inhabit it = Panbiogeography
Rejected concept of origin in a limited area & that of dispersal. Organisms always occupied the areas where we see them. Idea of vicariance.
Used a vast array of distributional data, representing each biogeographical pattern as a ‘track’, connecting its known area of distribution. Tracks of similar taxa combined to form a generalized track that connected different regions of the world.

9. 20th Century
Earth’s geography still assumed to be stable. Unable to explain the distribution of the glossopterus flora.
60’s – Invention of techniques that used magnetized particles in rocks to trace movement of the rocks & of the land masses in which they lay

10. 20th Century cont’d
If continents never moved, these “fossil compasses” should all point to present magnetic poles
Types of rocks laid down in the continents also shows this.
Also supported and confirmed by study of the ocean floor.

11. Divisions in Biogeography
Ecological biogeography – study of distributions & geographic variation of biotas, with special emphasis on the influences of interations between organisms and their abiotic and biotic environments.
Historical biogeography – study of development of lineages and biotas including their origin, dispersal and extinction
9 basic approaches

12. Patterns of Interest
Endemism – How did a taxa come to be endemic in an area?
Provincialism – If multiple taxa share same endemism, do they share same historical cause for present distribution?
Disjunction – Taxon on both sides of a barrier, is said to have disjunct distribution
Phylogeny – Hypothesis about distribution, also implicitly makes a statement about phylogeny.
Fossil record – Rich source of data on past distributions.
Historical Geology – Geologic action has a profound evolutionary effect. (continents coming together & moving apart; sea level rising & falling, glacial ice)

13. Processes of Biogeography
Dispersal – movement of organisms away from their point of origin. Basis that taxa are distributed via physiological adaptation and locomotion on a static Earth.
Vicariance – some barrier to genetic exchange causes the separation of the related taxa. Proposed in response to the discovery of a dynamic Earth. Organisms are forced to move (rising sea level) or move unwittingly (continental drift).
3 types of dispersal: jump dispersal, diffusion, secular migration

14. Processes of Biogeography
Speciation – evolutionary development of a biological species, as by geographical isolation of a group of individuals from the main stock. Formation of a new biological species by the development or branching of one species into 2 or more genetically distinct ones.
Extinction – fact of being extinguished; suppressed; coming to an end or dying out

15. Conclusion
Naturally integrative field of study that encompasses a broad range of methods, data, habitats, and organisms.
Helps us understand our planet; its geography, geology, and organisms, where they have interacted through time, evolving together to form the places we know today.
Comparative science that interprets the complexity of relationships and distributions of life on earth with respect to its geological history.
Common goal: to understand the relationship between life and its distribution.

16. Literature Cited
Cox, C. B. & Moore, P.D th ed. Biogeography: An Ecological and Evolutionary Approach. Blackwell Publishing.
Crisci, J.V., Katinas, L., & Posadas, P Historical Biogeography, An Introduction. Harvard University Press.
Huggett, R. J nd ed. Fundamentals of Biogeography. Routledge.
Lomolino, M.V., Riddle, B.R. & Brown, J. H rd ed. Biogeography. Sinauer Associates, Inc.
Parenti, L, & Ebach, M 2009, Comparative Biogeography : Discovering And Classifying Biogeographical Patterns Of A Dynamic Earth, University of California Press, eBook Collection (EBSCOhost).
Williams, D, Ebach, M, & Nelson, G 2008, Foundations Of Systematics And Biogeography, Springer, eBook Collection (EBSCOhost)