BIOL 1F90 Lecture Notes - Lecture 23: Species Problem, Genetic Drift, Habitat
1 Mar 2018
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Document Summary
Macro-: large, can be seen with naked eye. Describe how the spatial expression of genes, such as bmp4 and gremlin, affects pattern formation. A group of organisms that maintains a distinctive set of attributes in nature. Evolutionary changes that create new species (and groups of species) Occurs by accumulation of numerous microevolutionary changes (changes in single genes) Ma(cid:272)roe(cid:448)olutio(cid:374) has (cid:271)ee(cid:374) des(cid:272)ri(cid:271)ed as (cid:862)(cid:373)i(cid:272)roe(cid:448)olutio(cid:374) (cid:449)rit large(cid:863) Known number of species about 1. 4 1. 6 million. Estimates of unidentified species range from 2 to 100 million. A single species may exist in 2 distinct populations that are in the slow process of evolving into 2 or more different species. Amount of separation time for 2 populations. Short time likely to be similar and considered the same species. Long time more likely to show unequivocal differences. May find situations where some differences are apparent but difficult to decide if the 2 populations are truly different species.
