Biogeography
Shane Neiss
I. Definition of Biogeography
a. The study of the geographic distributions of organisms and the processes that result
in such patterns.
i. Historical Biogeography
ii. Ecological Biogeography
II. Darwin’s 3 main points
a. Neither the similarity nor the dissimilarity of the inhabitants of various regions can
be wholly accounted for by climatic or other physical conditions
b. Barriers of any kind, or obstacles to free migration are related in a close and
important manner to the differences between the organisms of various regions.
c. Inhabitants of the same continent or the same sea are related, although the species
themselves differ from place to place.
III. Patterns of Distribution
a. Endemic- limited to a particular geographic region (realm).
b. Cosmopolitan- found worldwide
c. Disjunct- distributions have gaps
IV. Historical Factors Affecting Geographic Distributions
a. Extinction- reduced distribution from loss of populations
b. Dispersal- species expand their range by movement of individuals
i. Range Expansion- movement across favorable habitat
ii. Jump Dispersal- movement across a barrier
c. Vicariance- separation of populations of a widespread species by barriers arising
from changes in geology, climate, or habitat.
V. Phylogeography- description and analysis of the process that governs the geographic
distribution of lineages of genes
a. provides insight into past movements of organisms that carry the genes, and can
attain current distributions.
VI. Paleontology
a. If fossil record is good, very important for explaining distribution
b. Can determine when a group arose