Phylogeny & Systematics Chapter 25

Phylogeny: the evolutionary history of a species

 Systematics: the study of biological diversity in an evolutionary context  Analytical approach  Focuses on morphological, biochemical and molecular resemblances Constructing a Phylogeny:

 The fossil record: the ordered array of fossil, within layers (strata) of sedimentary rock Constructing a Phylogeny:

 Sedimentary rock(?) :  Richest source of fossils  Lake Turkana Boy(1984) The fossil record

 Limitations? The fossil record

 Morphological and Molecular Homologies:  Homologies= similarities do to shared ancestry Constructing a Phylogeny:

 Homology vs. analogy  Convergent(independent) evolution vs shared ancestry  Similar environmental pressures can produce analogous adaptations in organisms from different lineages Some more challenges:

 The tracing of evolutionary relationships (phylogenetic tree)  Linnaeus(taxonomy)  Binomial Nomenclature Phylogenetics

 Binomial Nomenclature-two part naming system  First part: genus(genera)  Second part: species(specific epithet) Phylogenetics

Hierarchical Classification:

 1. Domain  2. Kingdom  3. Phylum  4. Class  5. Order  6. Family  7. Genus  8. Specie s Hierarchical Classification

 1. Eukarya  2. Animalia  3. Chordata  4. Mammalia  5. Primate  6. Homidae  7. Homo  8. sapiens Example:

 Classification is reflected in the branching of the phylogenic trees  Evolutionary relationships are traced between some of the taxa What is the connection between classification and phylogeny:

  Cladograms: diagrams that show patterns of shared characteristics   Clade: a group of species that includes an anestral species and all its descendants. Phylogenetic systematics:

  Cladistics: the analysis of how species may be grouped into clades Phylogenetic Trees

 Monophyletic- single ancestor that gives rise to all species in that taxon and to no species in any other taxon  The only valid clade(cladogram) Valid vs. non valid clades

 Paraphyletic- lacks information about some species  Consists of an ancestral species but not all descendants  Not valid Valid vs. non valid clades

 Polyphyletic-grouping of several species that lack a common ancestor  Not valid Valid vs. non valid clades

{ A Cladogram

This-File.swf  simevolution/obonu/cladog rams/Open-This-File.swf simevolution/obonu/cladog rams/Open-This-File.swf simevolution/obonu/cladog rams/Open-This-File.swf