Ethan Kupferberg 9/23/19Phylogenetic trees 1. Introducing trees and tree terminology 2. How to make trees from molecular data a. Parsimony 3. And if you don’t have molecular data? a. Homology and analogy 4. Putting events on trees 5. Does taxonomy reflect phylogeny? a. Monophyly vs. paraphylyThe first phylogeny: Common descent is that one population can become two different species that descended from a common ancestorTime runs from the bottom (past) to top (present)The Great Chain of BeingPhylogenies are equally evolved The two organisms with the most recent node are sister taxingParsimony:1. A preference for the least complicated explanation for a particular phenomenon 2. A phylogeny that requires the fewest independent evolutionary eventsOccam’s razor: principle urging one to select from among competing hypotheses that which makes the fewest assumptions. Cladistic parsimony: method of phylogenetic inference in the construction of types of phylogenetic trees (cladograms); support the hypothesis(es) that require the fewest evolutionary changes.Traits other than DNA can give us information about relatedness- Shared morphology - Developmental patterns - Behavioral patterns - Paleontological dataYou can use phenotypic traits on extinct speciesTraits arise through convergent evolution are called analogous occur on different linagesShared traits that are passed on from a common ancestor are called homologousWhen a new form of an ancestral trait evolves it is called a derived trait (synapomorphy)Bone structures are homologous across vertebratesThe bones are homologous, but the wings are analogousWhen making phylogenies, we must consider whether shared traits are homologous or analogous- Shared morphology - Developmental patterns - Behavioral patterns - Paleontological dataLUCA – Last Universal Common AncestorEukaryotes are monophyletic: A group containing its MRCA and ALL descendants of that MRCABacteria are also monophyleticThe MRCA for Archaea gives rise to all Archaeans, including the EukaryotesThe Prokaryotes are all living things that are NOT EukaryotesThe Prokaryotes are paraphyletic: A group containing its MRCA, but NOT all descendants ofthat MRCADinosaurs used to be paraphyletic…until we added the birdsBirds survived the K-PG extinctionThe Archaeans are a very recent case of regrouping to make a monophyletic nameTaxonomy not equal to
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