ANTB15- Notes on Assigned Readings.docx

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University of Toronto Scarborough
Larry Sawchuk

Big Picture on Evolution • This was the famed ‘modern synthesis’. • Genes may become inactivated but remain in the genome as pseudogenes. • Charles Darwin,
is remembered as the father of evolutionary thinking. • Natural selection: Those most suited to their environment survive at the expense of those less ‘fit’. > organisms produce more 
offspring than survive to reproduce. • One of the strongest cultural systems in language, which shows clear signs of evolutionary change • A change in DNA might be beneficial but is usually harmful. Often, though, it won’t make a blind bit of difference. This is known as a neutral change.  Living things fall into three major divisions: Bacteria, Archaea and Eukarya.  Archae: Although single-celled and lacking a nucleus, genetic comparisons suggest they are more  closely related to eukaryotes than to bacteria.  Hox genes: These are ‘master control’ genes that coordinate the activity of many other genes.  found throughout the animal world  No sweet tooth: cats are indifferent to sweet things because they cannot taste sugar- a gene coding for part of the sugar receptor is pseudogene  People were shorter than they are now. We do seem to be getting taller – but that’s due to better diet rather than any evolutionary change.  Mixing pots: Virus genomes can also swap bits of their genome with one another.  ‘primordial soup’ model: Stanley Miller’s famous experiment in the 1950s, where he mixed some simple chemicals, applied a strong charge, and stood well back; he managed to create complex ‘biological’ compounds such as amino acids.  A popular new idea is that life emerged at hydrothermal vents.  Creationism is a faith- based position that holds that life/people were created by God.  Creation science was a move to position this kind of thinking as legitimate science.  Intelligent design (ID) attempts to raise the same issues but without including a religious dimension by not specifically saying that God is the intelligent designer.  Darwinian views of evolution imply that all aspects of the biology of organisms must be adaptive – providing some kind of selective advantage – otherwise they could not have evolved. Applied to humans and their behaviour, this is known as evolutionary psychology.  Wallace outlined his theory in a letter to Darwin. Darwin feared being scooped, but also did not want to cheat Wallace. He consulted eminent friends, who suggested that  Darwin then set about describing all his evidence, which he published in On the Origin of Species in 1859  An early influential idea was that animals preferentially help their relatives, who share some of their genes.  The more closely related they are, the more likely they would be to collaborate.  Game theory studies, which explore people’s altruistic or selfish decision-making in various scenarios.  So mechanisms may evolve that lead to altruistic behaviour within a species because the long-term benefits outweigh the short-term advantage of selfishness.  indirect reciprocity – ‘I’ll scratch your back because I know someone will scratch mine’  Life has existed for 3.5 billion years INHERITENCE OF TRAITS article  Given the current size of the world’s population, the human genome is less diverse than might be expected  This observation is explained in part by two phenomena — the recent divergence of humans from other primates and the relatively small size of the human population over most of its history • In prehistoric times, the human population expanded in size as it migrated into new territory • Modern humans migrated out of Africa about 100,000 years ago • Mankind began migrating to America and Australia. • Famine, war, environmental disruption and infectious disease epidemics can all create POPULATION BOTTLENECKS • Immigration counteracts the effects of isolation, and can restore diversity quickly if it occurs before the isolate expands markedly in size • Genetic drift makes populations more different, but then gene flow can make populations more similar. As a result, gene flow reduces the effects of genetic drift.  The importance of deographic history: Unfortunately, for most isolates we lack reliable informa- tion on their initial genetic makeup, their total number of founders, and the extent and duration of their isola- tion.  More systematic analysis of DNA variation between and within populations is clearly needed. Such research, which is in its infancy, is a stated goal of the Human Genome Project.  Isolates such as the Lapps of Scandinavia (Saami-populations) and the Basques of southern Europe are well established (200–400 generations old) and demographically stable  Because of their small size and paucity of recessive dis- eases, these groups have been largely ignored by geneti- cists.  Of more value in mapping rare diseases are the Finns, Amish, Sardinians and Bedouins. These isolates also show a high frequency of certain Mendelian disorders and many disease genes have been identified in them.  For studies of complex traits, geneticists have tended to target younger population isolates (10–20 generations old) that originated from a small number of founders and underwent rapid population expansion.  The people in most isolates share a common environment and culture  Small isolated populations also offer unusual opportunities for the standardization of diagnostic and phenotypic criteria, which increases diagnostic reliability.  One example is Finland, where five medical schools with shared academic traditions train all the clinicians in the country.  national population registries are available for certain isolated populations. > the registries record births, deaths, marriages and migrations of individuals, and are of enormous value for the reconstruction of large pedigrees.  The most extensive example of the systematic use of population history, genealogical records and nationwide health-care registries in genetic research is the deCode project in Iceland  Some diseases, such as lipid disorders, offer better opportunities for quantification than other d
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