BIOL 152 1st Edition Lecture 9 Outline of Last Lecture Speciation Outline of Current Lecture Evolutionary biology Phylogeny the evolutionary history of a species or group of species Systematic analytical approach to understanding the diversity and relationships among organisms Morphological biochemical and molecular resemblances Taxonomy ordered division of organisms based on a set of characteristics used to assess similarities and differences Linnaeus Why fossils are important 90 of species that ever existed are extinct Reveal ancestral characteristics Substantial but incomplete Biased toward abundant species that dominated regions widespread and shows a display of only bony structures Analogy versus Homology Bat and bird wings are analogous Evolved independently via convergent evolution evolved separately Bat and cat forelimbs are homologous Evolved from a common ancestor These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Bird and bat humorous are homologous depending on the scale Taxonomy Binomial nomenclature genus and specific epithet ex Panthera pardus Leopard Latin universal avoid ambiguity Hierarchical classification species are grouped into increasingly broad inclusive categories Taxonomic unit at any level is called a taxon For example domain kingdom etc Phylogenetic trees branching of diagrams that depict hypotheses about evolutionary relationships done through Series of dichotomous branches Deeper branch points represent greater amount of divergence Cladistics Cladogram depicts patterns of shared derived characteristics Present in one population but not in ancestral populations Does not by itself imply evolutionary history Clade group of species that include ancestral species and all its descendants Monophyletic is a valid clade branches off one ancestor and shows many of its descendants Paraphyletic contains only some of descendants of its group Polypyletic grouping organisms that don t share a common ancestor Paraphyletic and polyphyletic are wrong versions of a cladogram Two kinds of homologies Shared Ancestral a character that is shared beyond the taxon we are trying to define For example backbones in mammals AKA synpleisiomorphic Shared Derived an evolutionary novelty that is unique to a particular clade For example hair in mammals backbones in vertebrates AKA synapomorphic Outgroups are used to differentiate between shared derived and shared primitive characters Species or group of species that is closely related to the ingroup are specifically the species we are studying Principle of parsimony the theory that the simplest explanation is the best solution aka Occam s Razor Molecular systematics Is used to comparing DNA to infer relatedness Above and below species level When morphological process are not possible researchers use the method of molecular systematics DNA that codes for rRNA changes slowly therefore these genes known to be highly conversed Researchers use this method to distinguish two distant organisms in a phylogeny mtDNA or mitochondrial DNA changes rapidly and so it is used for distinguishing closely related species Facts Bacteria and Archae are prokaryotes Neutral Theory is the theory that most mutations are neutral Genes that are changing slowly are affected by mutations which consequently affect survival Genes that are changing rapidly when affected by mutations do not affect survival Current Lecture Chemistry of Life