Anthropology 1026F/G Lecture Notes - Symmetry In Biology, Macroevolution, Genetic Drift

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Oct. 17, 2011
Macroevolution
- Variability & variation within species selected for survival
- How it happens at the cell level (micro)
- Macro = evolution above species level w/ focus on formation of species (speciation)
- Species = pop. Of organisms capable of interbreeding & producing viable fertile offspring
o Viable = functioning as individual organism
o Fertile = able to produce offspring
- Macroevolution key to understanding organisms within last 500 million years
Factors affecting macro
- Isolating mechanism
o Separates breeding pop.
o Prevents gene flow
o Creates divergent subspecies
o In time (if maintained) creates separate species
- Genetic separation, genetic drift, social factors
o Cuckoo bird calls
o Darwin’s finches on differing islands
Cladogenesis = recall clad Species B
Species A
Species A or C
Eg. Split between monkeys & apes
Anagenesis = sustained directional drift
Species A Species B
Evolutionary biologists differentiate between
- Variational change
o Gradual change over time
- Punctuated equilibria
o Long period of stability punctuated by periods of rapid change
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