BIO120H1 Lecture Notes - Lecture 9: Sympatric Speciation, Divergent Evolution, Reproductive Isolation
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BIO120H1 Full Course Notes
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Speciation: the formation of new and distinct species. Species concepts: taxonomic: morphological; based on morphological differences (not everyone agrees on the boarders between different species, biological: based on inter-fertility: different species cannot breed with each other. Ernst mayr: species = (cid:862)a group of i(cid:374)ter(cid:271)reedi(cid:374)g (cid:374)atural populatio(cid:374)s that are reprodu(cid:272)tively isolated fro(cid:373) other su(cid:272)h groups(cid:863) (bsc: no universal concept yet. Modes of speciation: allopatric: biological populations become isolated and develop into a new species (reproductive isolation due to a geographical barrier) Major form of speciation: sympatric: new species develops from a single ancestral species in the same location. Reproductive isolation: premating isolation: preventing zygote formation. Douglas schemske: m. lewisii and m. cardinalis (due to altitude differences) Parental species are inter-fertile in labs but the chance is very low: postmating isolation: preventing the proper functioning of zygotes. Can occur in f1 or f2 (sometimes occurs only in f2) Crow species in europe (due to poorly adapted hybrids/low fitness)
