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Lecture 3

Lecture 3.docx

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BIOL 359
Jonathan Witt

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Lecture 3:  Evolution: descent with modifications (population genetics ; change in population allele frequency)  Homology: similarity resulting from common ancestry ( the same origin), often despite differences in function  Analogy: Similarity in function, but not having the same evolutionary origin  THE history of life Special Creation Evolution: Descent with Modification Species do not change Species change over time Each species separately created Species derive from common ancestors Earth and life are old Earth and life are young • How did species arise: evidence for descent with modification and common ancestry will be considered  Is Biological Change Possible ?  YES; the domestication of Animals  The domestication of Dogs; dogs are descendents of Wolves: • Phylogenetic analyses unambiguously show that all domestic dogs descended from wolves (Canis Lupus) • The initial reason for why and how dogs were domesticated is a source of ongoing fascination • Selective breeding of dogs ; 6000 years o Scientific evidence supports two modes of evolution: o Microevolution: small evolutionary changes within species or populations o Macroevolution: referring to larger phenotypic changes sufficient to place an organism in a different higher level taxon ( e.g phylum families).  Over time microevolution results in macro evolutionary differences  Evidence for Descent with Modification:  Direct observation of change: soapberry bugs  The flat-podded golden rain trees were introduced to central florida  Some of the soapberry bugs made a shift from balloon vine fruit to flat podded golden rain tree fruit  The shifts show that beaks of the soapberry bugs who peak at the flat podded golden tree fruit has become smaller incomparison to those who feed on the balloon vine fruit. • not sufficient proof of evolution ; is it simple environment variation?  To determine if soapberry bugs are evidence of evolution, soapberry bugs of both beak sizes were collected and reared on both hosts.  Soapberry bugs specific to host flat podded golden tree fruit developed short beaks weather reared on balloon vine fruit or flat podded golden tree fruit  Soapberry bugs specific to Balloon vine fruit bugs developed long beaks weather reared on balloon vine fruit or flat podded golden tree fruit  Sibling species very close to divergence  Direct Observation of House sparrows:  Introduced into North American from Europe in 1852  Rapidly Spread Across North America  Populations have evolved differences in body size and coloration since that time • Ex) wing-length varies  Vestigal Structures and Organs: • Vestigial limbs: no longer functional, Vestigiality describes homologous characters of organisms that have seemingly lost all or most of their original function ...useless structures in organisms that possess of a) Rubber Boa: Vestigal Limbs; Snakes evolved from reptiles : b) Apteryx manetellin: a flightless bird c) Human Coccyx: Vestigial Tailbone, located at the end of the spine, has lots it original function in assisting balance and mobility. reflects that human ancestor had a tail d) Arrector pilli muscle; attached to hair follicles; hair will stick up when muscle contractions, for human’s it contracts when we are cold and gives us gossebumps  Gorilla use it when their cold or when their scared  Fossil Record  Extinction trilobites, e.g irish elk and trilobites Geographic Patterns in the fossil record  The Law of Succession: fossils in a given geographic region are more closely related to the extant fauna of that region than they are to organisms in a different geographic region  Transitional Forms  Example: archaeopteryx and sinosauropteryx • Dinosaurs are divided into two groups: ornthnischia and saurischia • Birds are descended of dinosaurs  Example: transitional forms in evolution of whales from ; contemporary whale, to basilosarus to ambulocetus natans o Intermediate form of aquatic mammal has a rudimentary pelvis  Testing Evolution as a Hypothesis and Testing it with the Fossil Record  Null Hypothesis: Evolution has not occurred  Prediction: We should see the same organisms that exist today throughout the entire Fossil Record  Alternate Hypothesis: Evolution has Occurred  We should see changes in the organisms that have inhabited the Earth throughout the fossil record, and there should be strong geographic patterns with respect to the similarity of organisms within the fossil record, and those that exist today  Relatedness:  Darwin’s trip to the Galapagos and his examination of mockingbirds, finches, and totoises lead him to recognize the relationships within these groups through shared ancestry  Phylogenetic tree: Darwin recognized that the pattern among closely related forms found on different islands are inconsistent with the ideas of special creation, but rather provide evidence of descent with modification, in a way that can represented by a tree  P
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