Biology 1001A Lecture Notes - Lecture 21: Parental Investment, Reproductive Isolation, Allopatric Speciation
19 Dec 2017
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Without speciation everything would be the same species (probably some sort of unicellular organism) Why does it matter how we define a species: to determine if two species differ and one is endangered, they could be a hybrid not a new species. Lumping vs. splitting (paying attention to similarities and classifying them together vs. paying attention to differences and classifying them apart) Still no perfect definition of species, 150+ years after origin of species. Morphological species concept: diagnostic physical characteristics: species= a distinct cluster in phenotypic space, non over lapping with other such clusters, or things that look the same probably belong to the same species. Has problems with sexual dimorphisms (different sexes look different) therefore they peg them as different species. Phylogenetic species concept: smallest possible monophyletic group (newest) groups: species=irreducible clade of organisms diagnosibly distinct from other such, many groupings categorized as (cid:494)subspecies(cid:495) by bsc are monophyletic would be recognized as species by psc.
