- Wright, Kimura, Ohta, Gould
- Most polymorphic alleles originate by neutral mutations and are maintained by
- 1. genetic drift
- 2. gene flow (rather than selection)
- Darwin, A Russel Wallace, RA Fisher, HJ Muller
- Most polymorphic alleles originate from Mutations w/some SELECTIVE value. These mutations w/favorable effects are MAINTAINED BY SELECTION, while those w/deleterious effects are LOST by selection
- JBS Haldene, Bruce Wallace, Theo. Dobzhansky, Kreitman, Dawkins
- Most pholymorphic alleles originate from mutations w/Favorable selective effects (in time, place or genotype) are MAINTAINED by BALANCE of Completely SELECTIVE FORCES.
- ie Sickle Cell Anemia: this can shorten lifespan of RBC to 90 days, but MALARIA parasite NOT able to survive, so there is genetically favored advantage to this
Biological Species conept
- Strongest Champion: Ernst Mayr
- Species defined as: Groups of INTERBREEDING (intrinsic) natural population that are isolated from other groups.
- Extrinsic - not able to interbreed & produce fertile offspring
- Shortcomings: can't classify prok, can't classify ASEXUAL beings
Phenotypic or Phylogenic Species concept
- Strongest champion: Joel Cracraft. (dead are Aristotle, Darwin, Lamarck, Linneus, Fisher)
- Phenogenic or Phylogenic clusters of organisms who share these traits based on ancestor-to-->descendent inheritance.
- Species defined: Based on Phenotype, NOT offspring
- Attempts to answer Product Question: why are we able to classify living organisms in a systematic and reproducible way
- Shortcomings: NOT Objective
Ecological or Evolutionary Species Concept
- Strongest Champion: George Gaylord Simpson. (dead are Wright, Simpson, Leigh Van Valer, Wiley)
- Species defined as: Lineage of organisms sharing SAME ADAPTIVE zone & evolutionary history
- Answers persistance question: why species able to maintain themselves as stable recognizable groups over time
- Shortcomings: may have something genetically distinct. Ie, cicadas have different lifecycles & NOT able to interbreed…arguing each are different species.