BIOEE1780 Notes 2/5-2/10
BIOEE1780 Notes 2/5-2/10 BIOEE1780: Evolutionary Biology
Popular in Biology: Evolution and Biodiversity
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This 3 page Class Notes was uploaded by Carly Siege on Wednesday February 10, 2016. The Class Notes belongs to BIOEE1780: Evolutionary Biology at Cornell University taught by Dr.Sarvary in Spring 2016. Since its upload, it has received 21 views. For similar materials see Biology: Evolution and Biodiversity in Biological Sciences at Cornell University.
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Date Created: 02/10/16
Pre-Lecture Synapomorphy: a derived character state that is shared by a common ancestor and all of its descendants table of synapomorphies derived: a character states in a present organism that was altered from an ancestor Outgroup: a group of organisms that is outside of the monophyletic group under consideration, but closely related to that group. In phylogenetic studies, outgrips can be used to infer the ancestral states of characters Species: the most fundamental unit of biological classiﬁcation -even in the best studied groups (vertebrates), new species can be found Latin Binomial: genus and species -always italicized -sometimes followed by the person who discovered the species -sometimes followed by the sub-species: trinomial name Linnaeus Hierarchical Classiﬁcation (does not reﬂect evolutionary history) Phylogenetic Classiﬁcation - every grouping is a clade (monophyletic) - names involve characters that represent that group - evolutionary transition is represented ^example of tree made In Class Character: any heritable train that can be used to determine relationships - morphological, molecular & behavioral characteristics - characters: wings, ﬂoral nectar, leaves, eye color, -vs character states: wing loss or reduced, present or absent nectar, hairy/non hairy leaves, blue, brown or green eyes… phylogenetic characters should be: Heritable: oﬀspring will have the same state as parents Slowly Evolving: two species that share a character state are likely to be closely related Homologous: character states should be alternatives of the same character Taxon (taxa): a group of organisms considered as one taxonomic unit Synapomorphy: A shared derived character state Monophyletic group: an ancestral species and all of its descendants (clade) paraphyletic group: an ancestor and some BUT NOT ALL of its descendants homoplasy: similar characteristics are nor due to a common ancestor, but instead due to either convergent evolution or evolutionary reversal —> homoplasy can mistake people into thinking two species are closely related when they’re not homology: characteristic that is similar which IS DUE to common descent convergent evolution: interdependent origin of similar traits in separate linages evolutionary reversal: the reversal of a character state from derived to ancestral IE. ancestor of replies who did not have legs —> recent reptiles with legs (lizards and turtles) —> a snake who went through an evolutionary reversal and lost its legs Pre-Lecture Adaptation: a trait, modiﬁed by selection, that increases the ability of an individual to survive or reproduce compared to individuals without the trait The comparative Method: how you can study adaptation when you can experiment directly Independent contrast phylogenetic contrasts tell us whether testes size and group size are actually evolving in concert on the tree. it so, that is evidence for adaptation over history of this whole group LECTURE choosing the optimal tree select the tree with the smallest number of character state transitions provides the simplest explanation for observations most common approach for morphological characters Character State Mapping instead of starting with character and making art, you start with a tree and map on the characters these characters should be as independent as possible from those used to build phylogenies as with building tress, you want to minimize the number of state changes to produce the simplest most optimal hypothesis you can map many diﬀerent traits: morphology, DNA, behavior, habitat, geography Biogeography: the study of the distribution of species in geographic space and through geological time - dispersal or vicariance Key Terms From the Week Branches: Represent lineages evolving through time between successive speciation events. Characters: Any heritable trait that can be used to determine relationships (e.g., morphological characters, molecular characters, and other characters). Character state: Whether character is present or absent, or particular form that the character takes (e.g., ‘tail’may be elongated / short). Clade: An ancestor and all of its descendants. Homoplasy: Character state similarity not due to shared descent. Monophyletic group: One containing an ancestor and all of its descendants (synonymous with clade). Node: Apoint on a tree where a lineage splits (speciation event). Phylogenetic tree (Phylogeny): Avisual representation of the evolutionary history of populations, genes, or species. Root: The base of a phylogenetic tree (branch to unseen ancestral taxa). Synapomorphy: Aderived form of a trait that is shared by a group of related species (i.e. one that evolved in the immediate common ancestor of the group and was inherited by all the descendents). Taxon (plural taxa): Agroup of organisms considered as one taxonomic unit (e.g., a species). Tips: The tips of the trees represent species or higher taxa, populations, or variants of biological molecules being compared Do animals really float across the ocean (dispersal)? YES especially after natural disasters like tsunamis Viral Evolution - HIV replicates very fast (10^8-10^10 nee viruses per day) - 75% of cases of HIV transmission, infection happen with one virus from the source individual - we need to get a flu shot every year because viruses evolve so quickly and are able to evolve inside of us
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