Bio Notes Speciation

Topics: Evolution, Phylogenetics, Species Pages: 2 (380 words) Published: May 7, 2013
A. Neutral Evolution
1. Kimura 1968 2. Proposed much of genetic variation is neutral 3. Neutral mutations do not affect phenotype a) Either do not alter product of gene b) Affect non-coding regions of DNA 4. Not subject to natural selection 5. Useful for reconstructing phylogenies

B. Speciation
1. Formation of new species from ancestral species 2. 2 components a) genetic isolation b) Genetic divergence 3. Adds new branch to the tree of life

C. Species Concept
1. Evolutionary independent population 2. Distinguished by common characteristics a) shared amongst members of species b) Set them apart from other species 3. Species arise as a consequence of a) lack of gene flow w/ other populations b) Subsequent ??

D. Biological Species
1. Reproductively isolated 2. Members of a species a) can interbreed b) produce viable offspring 3. Advantages a) Strong theoretical foundation w/ respect to Darwin’s Theory. 4. Disadvatages

a) can’t apply to fossils or asexual organisms b) can’t apply to geographically isolated populations

E. Morphological Species
1. Based on differences in morphology 2. Advantages: a) Widely applicable to fossils and both sexual and asexual organisms 3. Disadvantages a) Criteria subjective b) Intra-species morphological variation often greater that inter-species variation.

F. Phylogenetic Species
1. Based on ancestral analysis a) Phylogeny 2. Smallest identifiable group assigned species statu. a) Monophyletic group 3. Advantages a) widely applicable b) strong theoretical foundation 4. Disadvantages a) Few thorough phylogenies available

G. Ecological Species
1. Based on environmental context 2. Each species occupies unique niche 3. Avoid problems associated with a) Morphologically similair species b) Asexually reproducing species 4. Disadvantages a) Difficult to characterize niche in sufficient detail.

H. Speciation
1. Reproductive Isolation a) Allopatry: populations physically separated b) Sympatry: co-occurring...
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