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BIOL 110
Julia Roberts

1Zoology Midterm 1Monophyleticgroup of species belonging to the same genus family order class or phylum should share a unique common ancestor and comprise all the decedents of that ancestor Paraphyletica taxon that includes most but not all descendants of an ancestral formHomology ancestry Analogy function Homoplasy appearanceif the structures are homologous it helps with the classification of animalsAdaptation to similar environments may result in similarities that are that are not because of evolutionary relatedness but rather similar situations or capabilitiesEg Birds that do not fly ostrich or mammals that do fly bats Convergent and Parallel EvolutionConvergence similarity in animals with very different ancestors due to adaptation to similar environmental conditionsoEg the fishlike body form of dolphinsParallelism similarity in animals with similar but distant ancestors due to adaptation to similar environmental conditionsoEg the elongation of the distal part of the limbs of even and oddtoed hoofed mammals ungulates Homologous structuresevolve from a corresponding structure in a common ancestorAnalogous structuresmay appear similar but similarity is shaped by adaptation to a common function and does not reflect close evolutionary relationshipVestigial structuresnot functional but represent features functional in ancestorsRecapitulationancestral features are evident in the embryo of a descendent Paedomorphosisancestral juvenile features evident in the adult of the descendentProgenesisdevelopment of the reproductive system is accelerated in a morphologically juvenile stageNeotanywhen a somatic feature retains its juvenile form in the adultSexual Homologyrefers to structures derived from the same structure in the embryo but with different form and function in the adult male and female Structures that start off the same in the embryo but result differently depending on sex 2Serial homologyrefers to structures which are derived from similar embryonic structures in different embryonic segments Structures that develop from stages in the embryoOrigins of VertebratesPhylum chordates animals with a notochordNotochord flexible main axial support and the vertebral body of the vertebral columnHollow dorsal nerve cordGill slits in pharynxComplete gutPostanal tail Subphylum vertebrata chordates with a brain surrounded by a craniumHollow dorsal nerve cord above notochord with anterior brain adjacent to 3 special sense organs cephalization oNervous tissue over many generations becomes concentrated toward one end of an organism 3Cranium surrounding brainBilaterally symmetryAnterior mouth coelom around gut heart and lungs if presentoCoelom absorbs shock and provide a hydrostatic skeletonLarge sizeVertebrate OriginsThe origins are poorly known because the vertebrate ancestors were small soft organism s that do not fossilize well and lived long agoThe 3 subphyla of the phylum chordate were all present in the Cambrian periodCephalochordate small marine filter feedersoVertebratelike characteristics Genus amphioxusNotochord under hollow dorsal nerve chord Complete gut and postanal tailMidgut cecum homologue of liverPerforated pharynxSegmentationCoelomateEndostyle oNot vertebratelike characteristicsNo craniumNo special sense organs and associated brainNo kidneysNo heartUrochordata
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