Notes for exam 1

Notes for exam 1 - I. Intro to Comparative Vertebrate...

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I. Intro to Comparative Vertebrate Anatomy A. Syllabus B. Definition and realm of Comparative Anatomy 1. Well? 2. Generally- analysis of anatomy/ morphology of organisms and attempt to determine functional significance and homology of structure/ function a. First step- “What does it look like?” b. Next- why- functional and evolutionary reason(s) for fossil/present morphology 1) Functional morphology- relation of structure (architecture) to function (what it does) 2) Evolutionary morphology- relation of morphology to phylogenetic history c. Course emphasis- “what” and “why”- less so on “how” 1) How= embryological/cellular/biochemical events leading to structural formation 3. Constraints on anatomy and morphology a. Single structure- cannot serve 2 mutually exclusive functions 1) Often in biological systems- see compromise designs when single structure has 2 divergent functions- decreased efficiency or performance is typical 2) Phylogenetic derivation- structures arise from pre-existing structures- do NOT suddenly originate on demand a) Preadaptation- bad term- implies conscious evolutionary direction- don’t use ( exaptation is a better term)
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b) In an evolutionary context- many structures are precursors to homologous structures seen in later organisms Ex: reptilian forelimb- did NOT evolve in early reptiles so that it could give rise to wings 4. Paleontology- study of ancient organisms and events- provides the time frame and many intermediate forms of organisms a. Fossil record- vertebrates well- represented- why? Because bone is hard and is a mineralized b. Read sections on fossilization in text (geological time, scales) 1) Of the ~5 bill. Yr. history of earth, vertebrates present only ~550-600 MY- different classes of vertebrates dominate at diff. times 5. Other terms a. Similarities of structures 1) Homology- similarity in design- share a common ancestry (bird vs. bat wings) 2) Analogy- similar function- structurally and developmentally unique (bird wings vs. butterfly wings) 3) Homoplasy- similar appearance, no common ancestry b. Symmetry/ directionality 1) Radial, bilateral 2) Saggital, transversal, and frontal plane
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3) Anterior, posterial, lateral, dorsal, medial, ventral 4) Proximal and distal II. Evolutionary Constrains on Size, Shape and Function A. Size in biology an important consideration- relative size of an organism greatly limits what it can do/ how is affected by environment (heat, gas exchange, phenomena) 1. Physical forces such as gravity, buoyancy in water/air greatly affect organism design (you can’t escape gravity) a. Ex: ant vs. human falling off a building → differential effect of gravity (you may not survive) b. Ex: design of terrestrial vs. marine snakes → buoyancy of water supports sea snake body mass- affects design of musculature. (you use musculature to hold yourself up right using gravity) c. Scaling- as organisms get larger, demands on body parts change disproportionately: (as you get bigger, the affects of gravity are more important)
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This note was uploaded on 05/28/2011 for the course BIO 345 taught by Professor Dr.macessey during the Spring '10 term at N. Colorado.

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Notes for exam 1 - I. Intro to Comparative Vertebrate...

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