Investigating the Tree of Life

Investigating the Tree of Life - InvestigatingtheTreeofLife...

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Investigating the Tree of Life 04:18 Phylogeny Greek  o phylon : tribe o genesis : origin the evolutionary history of a species or group of species Utilities to construct phylogenies Fossil Record Systematics o o Molecular systematics:  evolutionary relationships between individual genes and even  between entire genomes
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25.1: Phylogenies are based on  Common Ancestries inferred from  Evidence 04:18 The Fossil Record Based on the sequence in which fossils have accumulated in strata Sedimentary rocks: richest source of fossils A large no. Earth’s species probably did not die in the right place at the  right time to be preserved as fossils Biased in favor of species that o Existed for a long time o o Hard shells, skeletons / other parts that facilitated their fossilization Homologies o Similarities among living organisms can indicate phylogenetic history o Exception o Big morphological difference  BUT  small genetic divergence Sorting Homology from Analogy o Genetic comparison o Observation of ancestors (fossils) o Homoplasies Analogous structures that have evolved independently o Consideration of the complexity of the characters being compared < points of resemblance » > likely independent evolution Sharing of many portions of nucleotide sequences Evaluating Molecular Homologies Technical challenges because of mutations o Accumulation / Deletion o Molecular homoplasy: where 2 not closely-related organisms that could  share parts of bases in their nucleotide sequences 
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25.2: Phylogenetic systematics  connects classification with evolutionary history 04:18 Taxonomy:  an ordered division of organisms into categories based on a set  Binomial Nomenclature Genus ( plural,  genera)  – 1 st  part of species’ name to which the species  belongs o CAPITALIZED Specific epithet  – 2 nd
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Investigating the Tree of Life - InvestigatingtheTreeofLife...

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