1. A. tigris punctilinealis and A. tigris marmorata OR A. tigris and A. marmorata? 3. One species or two? Fertile hybrids

2. The hybridization zone: SW New Mexico

3. Three concordant step-clines

4. Hybrid zones 1. Fitness of hybrids less than parental species. Hybrid zone narrow. Reinforcement. Differences between parental populations increase. 2. Fitness of hybrids equal to parental species. Hybrid zone broad. Parental populations converge; Differences between parental populations decrease. 3. Fitness of hybrids greater than parental species. Stable hybridization zone or speciation. –Red wolf?

5. Secondary contact Pattern of variation Low variation in F1s High variation in F2s, F3s, etc. Measure of variation (continuous characters) –CV = coefficient of variation –CV = (s/mean) x 100

6. Release of F 2 variation Mimulus lewisii Mimulus cardinalis

7. Aspidoscelis tigris

8. Secondary contact center

9. Primary contact Aspidoscelis tigris

10. Aspidoscelis velox (3n, parthenogenetic) 1. A. gularis stictogramma  x A. inornata  2. F 1 diploid parthenogenetric  x A. inornata  Aspidoscelis uniparens (3n, parthenogenetic) 1. A. inornata  x A. gularis stictogramma  2. F 1 diploid parthenogenetic  x A. inornata  Problem 4: Cryptic species velox uniparens

11. Barriers to interspecific hybridization Reproductive isolating mechanisms A. Prereproductive (favored by natural selection) –1. Ecological Temporal (phenological) Habitat segregation –2. Behavioral –3. Mechanical B. Postreproductive –Gametic wastage Other species concepts

12. Phylogenetic Species Concept(s) Phylogenetic species: the smallest aggregation of individuals diagnosable by a unique combination of character states. Characters and character states Organisms are grouped into species because of shared derived character states inherited from a common ancestor Ancestors and derived species form a branching pattern of divergence Ancestral populations do not (by definition) persist past a speciation event.

13. Greya (moth genus): mtDNA data Interpretations different with different species concepts

14. The Evolutionary Species Concept –E. O. Wiley. 1978,1981, 2001. A species is an entity composed of organisms –maintaining its identity from other such entities through time and space –and having its own independent evolutionary fate and historical tendencies. Operationalism absent Use fixed diagnostic differences