Phylogeny & Systematics Chapter 25

Phylogeny: the evolutionary history of a species

The study of biological diversity in an evolutionary context Analytical approach Focuses on morphological, biochemical and molecular resemblances Systematics

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

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

Limitations? The fossil record

Inferring a Phylogeny: Morphological and Molecular Homologies: Homologies= similarities do to shared ancestry Inferring a Phylogeny:

Inferring a Phylogeny:: Homology vs. analogy Homoplasies- independent evolution of analogous structures Bat and butterfly wings Inferring a Phylogeny::

Inferring a Phylogeny: Homology vs. analogy Convergent(independent) evolution vs shared ancestry Similar environmental pressures can produce analogous adaptations in organisms from different lineages Example of Convergent Evolution: Steatopygia Inferring a Phylogeny:

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

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

Hierarchical Classification:

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

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

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

Phylogenetic systematics: 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

Valid vs. non valid clades 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

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

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

A Cladogram