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2009. Evoluce genomů. FOXP2. = forkhead box 2 mutation in this gene were found in families that have a high incidence of abnormalities in speech and grammar only one aminoacid substitution had occured in the 130 Myr separating mice and ancestor of humans and chimpanzees
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2009 Evoluce genomů
FOXP2 • = forkhead box 2 • mutation in this gene were found in families that have a high incidence of abnormalities in speech and grammar • only one aminoacidsubstitution had occured in the 130 Myrseparatingmice and ancestor of humans and chimpanzees • two substitutionoccured in the human lineageduring the 4-6 Myr since it separated from chimpanzees! • this gene is virtually invariant in another 28 orders of mammals that last sharedcommonancestoraround 100 million years ago • (Futuyma, D.J., (2005) Evolution. SinauerAssociates, INC. Sunderland, MA,USA. p. 455)
MYH • = sarcomeric myosin heavy chain • MYH is highly expressed in the chewing muscles of chimpanzees and is responsible for the large size of these muscles in this and other non-human hominins • in humans, MYH has been inactivated by a frameshift mutation that occured about 2,4 Myr
OR • = olfactory receptor genes • these are approximately 1200 functional OR genes in the mouse genome, but only 550 in humans • = apparently selective pressures to maintain OR gene functionally are relaxed in humans
Olfactory Receptor Genes • the remoteancestor of mammalscarried a single gene for detectingodors that has been duplicated many times • as a result, humans today have about 1 000 olfactory receptor genes • mice have 1 300 • more recently , about 60% of human olfactory receptor genes have been inactivated by mutations • whereasmice have lost only 20% of theirs • …this dramaticdifference demonstrates that a versatile sense of smell is more important to mice than it is to us!