Chapter 25 - CR

Chapter 25 - CR - Chapter 25 Phylogeny and Systematics 1 of...

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1 of 25 of 25 Chapter 25 Chapter 25 Phylogeny and Systematics Phylogeny and Systematics
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2 of 25 of 25 Investigating the Tree of Life Investigating the Tree of Life Phylogeny : The evolutionary history of a species or group of related species Based on common ancestries inferred from fossil, morphological, and molecular evidence The Fossil Record provides information about ancient organisms Systematics is used as an analytical approach to understanding the diversity and relationships of organisms, both present-day and extinct Infers evolutionary relationships based upon morphological, biochemical, and molecular comparisons
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3 of 25 of 25 The Fossil Record The Fossil Record Sedimentary rocks are the richest source of fossils The most common type of fossil Are deposited into layers called strata The fossil record is based on the sequence in which fossils have accumulated in such strata Fossils reveal ancestral characteristics that may have been lost over time 1 Rivers carry sediment to the ocean. Sedimentary rock layers containing fossils form on the ocean floor. 2 Over time, new strata are deposited, containing fossils from each time period. 3 As sea levels change and the seafloor is pushed upward, sedimentary rocks are exposed. Erosion reveals strata and fossils. Younger stratum with more recent fossils Older stratum with older fossils Figure 25.3
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4 of 25 of 25 Morphological and Molecular Morphological and Molecular Homologies Homologies Phylogenetic history can be inferred from certain morphological and molecular similarities among living organisms In general, organisms that share very similar morphologies or similar DNA sequences are likely to be more closely related than organisms with vastly different structures or sequences Sorting Homology from Analogy A potential misconception in constructing a phylogeny is similarity due to convergent evolution , called analogy , rather than shared ancestry
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5 of 25 of 25 Analogous Features Analogous Features Convergent evolution Occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages Analogous structures or molecular sequences that evolved independently are also called homoplasies Figure 25.5
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6 of 25 of 25 Phylogenetic systematics Phylogenetic systematics Connects classification with evolutionary history Taxonomy Is the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differences Binomial nomenclature Is the two-part format of the scientific name of an organism Was developed by Carolus Linnaeus The binomial name of an organism or scientific epithet Is latinized Is the genus and species
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7 of 25 of 25 Hierarchical Classification
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This note was uploaded on 04/07/2008 for the course BIO 103 taught by Professor Mannino during the Fall '08 term at Long Island U..

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Chapter 25 - CR - Chapter 25 Phylogeny and Systematics 1 of...

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