BIO SCI 94 Chapter Notes - Chapter 27: Zygote, Helianthus Annuus, Zygosity

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Catherine Loudon

Document Summary

Four evolutionary process: natural selection, genetic drift, mutation, & gene flow. If gene flow ends, allele freq in isolated populations = free to diverge = pop begin to evolve independently of each other. Speciation results from genetic isolation and genetic divergence. Gene isolation: results from lack of gene flow. Genetic divergence - occurs because selection, genetic drift, and mutation proceed independently in the isolated populations. Speciation: splitting event that creates two or more distinct species from a single ancestral species. Speciation complete --> new branch added to tree of life. Species: an evolutionarily independent pop or group of pop. 3 most common ways to indentify species: biological species concept, morphospecies concept, phylogenetic species concept. Main criterion for indentifying species is reproductive isolation. No gene flow occurs between populations that are reproductively isolated from each other. If two diff pop can"t interbreed/fail to make fertile offspring = considered distinct species.