lecture outlines for posting14

lecture outlines for posting14 - Lecture 14 - EEB 13 - 26...

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Lecture 14 - EEB 13 - 26 February 2008 Dr. Hespenheide 5. classification of species - systematics - Linnaeus’ hierarchical system taxon (pl: taxa) [name] [another taxon at same level] Kingdom Animalia Plantae phylum (pl: phyla) Chordata Arthropoda (insects) class Mammalia Aves (birds) order Carnivora Proboscidea (elephants) family Canidae Felidae (cats) genus (pl: genera) Canis Vulpes (foxes) species familiaris (dog) lupus (wolf), latrans (coyote) representation as phylogenetic tree - sequence of divergences: (recent) dog wolf coyote cats elephants birds insects plants bacteria -dogs time -carnivores -mammals -chordates -animals (ancient) -eukaryotes -prokaryotes -(origin of life) How to represent phylogeny in a classification? - problems How to distinguish homology from analogy? - traits shared by common ancestry or convergent evolution (“homoplasy”)? How to recognize whether a particular trait is ancestral or derived – - solution: look at a known older ancestor of both (an “outgroup”) How to recognize whether two species have a common ancestor - - solution: they share a derived character(s)/trait(s) (“synapomorphies”) inherited from that ancestor
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- example – relationships among birds and their ancestors birds and “reptiles” [have feathers, fly [have scales, walk “warm-blooded”] “cold-blooded”] - these two groups are easily distinguished - are they clades? - we know sequence of divergences from fossils: lizards “dinosaurs” birds traits: abcde a’bcde a’b’c’d’e │ - b’c’d’ - a’ [ancestor] │ traits: abcde
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lecture outlines for posting14 - Lecture 14 - EEB 13 - 26...

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