1. Phenotypic variation in the GAB character A. sexlineata: reproduces sexually Recombination of homologous chromosomes A. tesselata: reproduces parthenogenetically Recombination of sister chromosomes Therefore, source of variation in GAB is not recombination. Conchas: GPI variation GPI ac: low counts ancestral GPI ab: high counts

2. Variation among 18 killifishes for phosphoglucomutase Alleles

3. Patterns of Geographic Variation

4. Arrangement of phenotypic variation in natural populations Some populations recognized as subspecies A biological race = a subspecies. Phenotypically diagnosable populations occupying allopatric subdivisions of the range of a species. Subspecies have accumulated different allelic variation (via mutation). Therefore, they express different fixed characteristics.

5. Example of subspecies Recognizable subspecies would have to be allopatric. Colaptes auratus cafer Colaptes auratus auratus

6. One problem: discordant character variation Parapatric distributions with intergradation at boundaries

7. Second problem: subspecies may be nothing more than slices of clinal variation Cline = a character gradient E.g. human race concept. There is no satisfactory biological definition of a human race! Misconception: there are character states unique to particular groups of humans The characters traditionally used are quantitative characters with continuous variation.

8. “Racial” characters are quantitative characters continuous characters e.g. skin color Phenotypic expression in and among populations generally fits a normal distribution

9. A common “racial” characteristic is skin color.

10. These groups easy to identify because of non-overlapping variation. Gaps 685 nm

11. Skin color in 22 human populations Samples of males Mean +/- one standard deviation Clinal variation

12. There IS geographic structuring of allele frequencies. Genetic distance map 42 native human populations Distances based on frequencies of 120 different alleles Closer proximity in graph = greater genetic similarity Genetic similarity is related to geographic distances among the groups. PPPPPopu Population differences