BIOL 202 Lecture Notes - Lecture 2: Animal, Polyphyly, Monophyly
20 Jan 2016
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Tardigrades (water bears: earth"s most tenacious creature , can survive from 1 k to boiling water, vacuum of space, can be dehydrated, dormant for 10+ years, dna composed of 50% metazoan, and 17. 5% foreign (highest percentage ever found) Taxa: a group of animals that share a particular characteristic: characteristics can be genetic, morphological, developmental etc. Phylogeny: hypothesis about the evolutionary history of groups. Groupings reflect organization from shared evolutionary histories. Creating a hierarchy allows for relative differences: ex. we find new species most often, not new kingdoms. Predictions of how many species exist within a taxa can be based on plateau behaviour in increasing larger taxa (phylum plateaus in discovery rate, but species has not yet) Can still discover new large taxa (like phyla: cycliophora discovered in 1995, feeding stages attach to the mouthparts of lobsters, live on lobster claws, awarded new phyla designation for odd life cycle (bears offspring inside itself)
