Speciation in sympatry happens via polyploidy

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Speciation in sympatry Happens via polyploidy Disruptive selection also causes Population separates into two even though species are able to mate Adaptive radiation When an environment in which species are close in proximity but must be separate with various species Places like island chains are prime examples Hawaiian native silverswords are thought to have descended from a single immigrant species
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9/26/18 ---------- Phylogenetic trees Common descent - two species can be formed by one species that separated All organisms have a common ancestor Each species comes from a pre-existing species Branches represent genetic change Nodes represent speciation events Phylogenies are horizontal, time is vertical Every species at the same level still exists together Sister taxa - organisms on a tree with a shared MRCA When flipping trees, sister taxa must remain together Outgroup - the most close group of organism that is outside of the target observed group Ex. ingroup: humans → outgroup: primates Trees are developed through examining mutations in genetic material Majority of shared bases allow for a closer pairing on trees Parsimony A preference for the least complicated explanation for a particular phenomenon A phylogeny that requires the fewest independent evolutionary events Occam’s razor: principle urging one to select from among competing hypotheses that which makes the fewest assumptions Traits other than DNA can give us information about relatedness (phenotypical) Shared morphology Developmental patterns Behavioral patterns Paleontological data Convergent evolution - when traits develop independently Analogy/homoplasy Homologous - when a new form of an ancestral trait evolves Derived trait (synapomorphy) Homologous structures can look very different In birds, bones can be homologous but wings can be analogous Eukaryotes are monophyletic : A group containing its MRCA and all descendants of that MRCA The prokaryotes are paraphyletic : a group containing its MRCA, but NOT all descendants of that MRCA Dinosaurs used to be paraphyletic…...until we added the bird Birds are dinos The Archaeans are a very recent case of regrouping to make a monophyletic name Taxonomy =/= phylogeny
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