CAS BI 309 Lecture Notes - Lecture 34: Notochord, Coevolution, Allopatric Speciation
30 Mar 2018
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Gerhart inversion of body axis from annelids to chordates. Synapomorphies (shared derived traits) of chordates: notochord, dorsal nerve cord, pharyngeal slits, post-anal tail protostomes vs deuterostomes (mouth/anus first) Inversion hypothesis: nerve cord, heart, dv axis = ectoderm in flies and mesoderm in chordates non-defined neural net = primitive bmp evolved later which represses neural tissue antagonist of bmp later evolves; , cns is established. Persons trio of paradigm shifts feather=aves integumentary feathers evolve from scales not flat but follicle is cylindrical feathers always selected for aerodynamic purposes. Endothermy in dinosaurs why would ectothermic animal need feathers? upright locomotion/fast; high growth rate = fast metabolism = endothermy birds are endothermic. Thermal insulator theory traps warm air close to body. Intro: hook, supporting information, last sentence is testable hypothesis. Body/results = predictions if hypo is true discussion/conclusions = start with background, implication/confidence in results/ limitations, alternative interpretations, conclusion, and then future endeavors. Anisogamy: ova more costly, female preference drives sexual selection.
