BIO SCI 94 Lecture Notes - Lecture 5: Phylogenetic Tree, Gray Wolf, Comet Nucleus

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

The ambiguity involved in the concept of species and speciation can be frustrating for students. Speciation is a gradual process- there is no obvious signpost at which two populations have sufficiently diverged to be considered different species. Speciation is a splitting event that creates two or more distinct species from a single ancestral group. Genetic divergence: due to selection drift and mutation. A species is de(cid:256)i(cid:295)ed as (cid:717)a(cid:295) evolutio(cid:295)arily i(cid:295)depe(cid:295)de(cid:295)t populatio(cid:295) or (cid:257)roup o(cid:256) populatio(cid:295)s(cid:718) But it not that simple there are three criteria for species. Biological species: if two individuals can successfully produce offspring, they are in the same species. Problems with the biological species concept include: Hard to access if populations are not in contact with one another. According to the biological species concept, different species are reproductively isolated if: The breed but don"t produce viable, fertile offspring. Biologists categorize the mechanisms that stop gene flow between populations as either. Individuals of different species are prevented from mating.