Biology 1001A Lecture Notes - Lecture 21: Chromosome, Genetic Drift, Parental Investment
3 Apr 2016
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Each branching event = a speciation event 2 populations becoming reproductively or evolutionarily isolated: mechanism: speciation, if no speciation, there would still be microevolution: speciation within single lineage. No biodiversity on earth everything would belong to same species unicellular organism. Darwin said little about how species are formed and what constitutes a species. Lumping vs. splitting: determine whether or not 2 populations belong to same species: lumping: paying attention to similarities and classifying them together, splitting: paying attention to differences and classifying them together. 150+ year after origin of species, still no perfect definition of species. Over 50 species concepts have been proposed. Species: a distinct cluster in phenotypic space, non overlapping with other such clusters. Things that look the same, they probably belong to the same species. Everything in 1 cluster is the same species as everything else in that same cluster.
