BIOLOGY 1M03 Chapter Notes - Chapter 26: Dusky Seaside Sparrow, Species Problem, Phylogenetic Tree
26 Oct 2016
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Speciation occurs when populations of the same species become genetically isolated, diverging from each other. Populations can be recognized as a distinct species if they have distinct morphological characteristics, use different sets of resources, or form independent branches of a phylogenetic tree. Populations, when they come back together, could fuse, diverge, differentiate partially, form hybrid zones, have offspring that form a new species or go extinct. Researchers use all four concepts to identify species. If two groups do not breed or fail to produce viable offspring. Split into prezygotic isolation (prevents individuals from mating) and postzygotic isolation (offspring do not survive or reproduce) Morphospecies concept: dependant on size, shape, or other morphologic features. Species with similar features are likely to arise from populations that are independent and isolated from gene ow. Disadvantages: 1) cannot identify cryptic species (morphologically identical but are a different species), 2) features are subjective (different people can disagree)
