01:119:115 Lecture Notes - Lecture 21: Eastern Spotted Skunk, Cichlid, Sympatric Speciation

• School: Rutgers University
• Department: Biological Science
• Course: 01:119:115
• Professor: All

Document Summary

The fitness of phenotype declines if too common in population. Selection favors whichever phenotype is less common in population. Fig 23. 18 frequency dependent selection selects for approx equal number of (cid:498)right- mouthed(cid:499) dom)nant and (cid:498)left-mouthed(cid:499) scale-eating fish. Selections an act only on existing variations (may not be ideal) Evolution is limited by historical constraints (operates on traits an individual already has) Chance, natural selection, and the environment interact. Chapter 24 changes occur (genetic variation) but descendant is clearly same type as ancestor. Microevolution varieties within a given population or species; members interbreed. Macroevolution major evolutionary changes over time, the origin of new types, species from previously existing, but different, ancestral types (cid:523)can"t interbreed(cid:524) A biological species: where members interbreed in nature and produce fertile offspring . Concept 24. 1 biological species concept and reproductive isolation emphasizing differences between species. Emphasizes reproductive barriers preventing interbreeding (fig 24. 2a) But excludes hybrids (gene flow) that can results from interbreeding.