lec 2 eeb388.docx

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Ecology & Evolutionary Biology
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lec 2 classification of mammals 9/21/2012 10:33:00 AM Phylogenetics:  Finding relationships between organisms via their last common ancestor via shared derived characters SYNAPOMORPHIES o Derived by all the taxa but shared with but all the ancestors share it aswell Evolutionary taxonomy***  G.g simpson(he produced classification of mammals) + E mayr : trying to develop theoretical framework for classifications o Degree to relatedness: overall similarity o Degree that they diverged/dissimilar  Genetic info to one another o Utilitarian device  classification o Most museums use g.g simpson system only problem with system was blending 2 degree  Ex. Simpson recognized relationship b/t deer and whales but since genetically he knew they were similar but physically looksed so different didn’t put them together. But the whole point is to show the most recent common ancestor so he did it wrong Phenetic/numerical taxonomy was based on similarity+dissimilarity sokal,sneath  We could not figure out genetic relationship because we were basing it on morphological characters appearing and disappearing because we could not do genetic sequencing  Using genetics + computers Phylogenetic systematics***  Ignore shared primitive elements  Ignore convergent elements  Rely simply on shared derived characters  Base classification system on relationships of organisms  Most reliable system to derive relationships o And indicating special relationships and reflecting evolutionary tree among organisms o As we redefine relations change classifications  Artiodactyla and cetacea should be the same order because cetacea come from artiodactyla 1 Mammalian Classification  Mckenna used phylogenetic systematics a wrong realtionship o Rodents,elephant shurds,lygamorphs  Also : archonta: 1970 gregory : tree shrews, primates, bats, gliding lemurs: bats don’t fit Evolutionary relationships and evolution of mammals very related to continental drift  Ex.africa: lots of animals derived from here: AFROTHERIA ex. Tree shrews, aardvarks  Armadillos: early eutherian mammalian group still not sure where they fit: sloths, soaft American ant eaters  strong suggestion that they are most related to this afrotheria still debated though  Old archonta minus bats : flying lemurs, tree shrews, primates + rabbits and rodents  now new group  Eurasia : northern contentant: cirisamorpha: shrew like,carnivores and pholidotes, and hoofed animals, bats in this group now  New classifications all based on genetic data  How hoofed animals and whales are related is a double fast ankle bone: shared derived character but whale does not have ankles now.. o Fill ginger which @ teefy sea : found early whale with ankles and double poulious stragalus st Rodents have 1 order of the most 2500 Bats are 2 nd1000 species of bats : in Ontario 9 species of bats Class Mammalia (mammals) Based on reproductive manners The first mammals all layed eggs that was the first characteristics: probably small eggs that hatch really early  Subclass prototheria (egg laying mammals) platy pus and spiny echidna o Order monotremata (monotremes)  Ex.spiny echindna, mother has a pouch and egg hatches in pouch. 2  no teeth, beack  all of which are derived and crazy chromosomes  Australia, new guinea before used to be in south America and Antarctica  No one is primitive, every mammal is mixed with ancesteral and derived characters  Ex. Platypus: thought was s hoax
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