Biology 2485B Lecture Notes - Lecture 3: Sympatric Speciation, Allopatric Speciation, Species Richness
1 Feb 2018
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Speciation produces new types of organisms: speciation: process by which new species are generated, allopatric speciation (main type): the emergence of a new species as a result of the physical separation of populations over some geographical distance, ex. In order for speciation to occur, populations must remain isolated for a long time, generally thousands of generations. Phylogenetic trees and similar types of diagrams show the history of life"s divergence, and illustrate relationships among groups of organisms. Each branch from the main trunk represents a speciation event. By mapping traits onto phylogenetic trees, biologists can study how traits have evolved over time. In (a), several major traits are mapped; triangular arrows indicating the point at which they originated. For instance, all vertebrates above the point at which jaws are indicated have jaws, whereas lampreys diverged before jaws originated and thus lack them.
