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UNCW BIO 358 - Overview of phylogeny and pinniped evolution

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BIO 358 1st Edition Lecture 5 Outline of Last Lecture I. Characteristics of Order CetaceaII. Classification III. Suborder MystecetiA. BalaenidaeB. BalaenopteridaeC. EschrichtiidaeD. NeobalaenidaeII. Suborder OdontocetiA. PhysteridaeB. KogiidaeC. ZiphiidaeD. MonodontidaeE. DelphinidaeF. PhoconenidaeG. PlatanistidaeH. IniidaeI. LipotidaeJ. PontoporiidaeOutline of Current Lecture II. Definition of Phylogeny: A. Monophyletic cladesB. Paraphyletic clades C. Polyphyletic clades III. Clade Handout Notes: IV. Identifying Monophyletic Groups:A.Investigate charactersB.Group them together based on similar characters V. Synapomorphies vs. Convergent Characters VI. Pinniped EvolutionVII. Cetacean EvolutionCurrent LecturePhylogeny:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- "tribe genesis"- Evolutionary relationships- Correctly identify monophyletic clades Monophyletic Clade:- "One tribe, group/taxon) - A group that contains an ancestor and ALL of it's descendants - EVOLUTIONARY VALID GROUP Paraphyletic Clade:- AN EVOLUTIONARY INVALID GROUP = PARAPHYLETIC CLADE- "Around, near group"- A group that includes an ancestor and only some of its descendants - Family = mom, dad, brother, me = monophyletic- Family = mom, dad, no brother = paraphyletic, invalid evolutionarilyPolyphyly group = Invalid evolutionary group- "Many tribes"- A group that contains the descendants (some or all) of multiple ancestors- diphyl: polyphyly with two separate ancestors Monophyletic is the only valid evolutionary grouping Clade Handout:ABCD = evolutionary groups/taxa/clades 1,2,3 = position of shared common ancestor1 = hypothesized common ancestor of ALL2= hypothesized common ancestor of BC and D3 = hypothesized common ancestor of C and D nice nested cones that fit well with each-other = monophyletic How do we identify monophyletic groups?1)investigate traits/characters across organisms--morphological--molecular2) group organisms together based upon similarities of traits --similarities MUST be due to shared common inheritance= HOMOLOGY --homology = similarity shared by common inheritance --ie. we have 4 limbs = tetrapods = makes me different from a fish... but how does it make us different from a cat or a dog... need more specific homologies... need something more specific to tell species apartSynapomorphy: -"shared, derived trait" -shared derived trait that uniquely defines a monophyletic clade-all synapomorphies are homologies Convergent Character: similarity based on shared common FUNCTION (not inheritance) -i.e. these characters will have independent evolutionary histories. -homoplasy = same thing Pinnipeds evolution: -large body size-blubber-specialize fur-SPECIALIZED APPENDAGES gives them their names -enhanced diving-enhanced thermoregulation-enhanced sensory systems-ARE THESE SYNAPOMORPHIES or CONVERGENT CHARACTERS? Evidence of Dyphyly -fossil record pre - 1989 PACIFIC ATLANTIC ~23 million years ago ~23 million years ago found phocids -fossils for odobenids and otariids - oldest known phocids ~4 million years ago = oldest phocid 19 million years of independant evolutionary history between the otoriids and odobenids and the phocids... On face value suggests 19 million years of independent evolutionary history between the odobenids and the otoriids vs. the phocids don't see first phocid for 19 million years in the pacific MUST BE THAT SIMILARITIES ARE CONVERGENT!!!researchers avoided the use of highly functional characters when building phylogenies...do pinnipeds use their appendages in a similar method? 1988 - graduate student questioned the premise of earlier studies - Andre Wyss-looked broadly across pinnipeds and other terrestrial carnivores and identified similarities -INCLUDED APPENDAGES which people were avoiding-demonstrated that all of the animals share synapomorphies across all of their body parts including flippers Enarliarctos:-fossil from the pacificA. Berta et. al. 1989 - discovered this fossil -greater than 23 million years old-transitional form - swam with both fore and hind limbs -suggests shared common ancestry of all pinnipeds in pacific - longer ago than 23 million years ago Cetaceans - Are they more closely ralated to mesonychids or artiodactyls? easy to identify similarities between mustelids and ursids... what about sperm whale - how does one identify relationships to terrestrial mammal when extant species are so highly derived?!-what are the synapomorphies?!-Linnaeus identified them as fishPlan A = fossils -not complete data set-BUT the earliest cetaceans were less derived than extant forms-morphological similarities between cetaceans must be closer toPlan B- molecular data-different type of characters so morphology is not required-problem = only identifies relationships between extant species-similarities between cetaceans and related terrestrial mammals will be more clear. When plan A and plan B tell you two completely different stories? Fossil record shows they are most closely related to mesonychidsMesonychids:- odd toed ungulates- most closely related to cetaceans- small wolf like animalMolecular data shows something


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