Phylogeny and Systematics

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Chapter 25

• Phylogeny and Systematics

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Phylogeny

• The evolutionary history of a species or group of
  species.

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Systematics

• The analytical study to understanding the
  diversity and relationships of organisms

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What data is used?

• Fossil records
• Remember- youngest species are in the upper strata

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What data is used?

• Molecular homologies
• Compare amino acids sequences
• Amount of heat needed to separate hybrid DNA

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What data is used?

• Morphological homologies
• Homologous and vestigial structures
• BUT be careful of analogous structures

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Carolus Linnaeus

• Developed system of Taxonomy
• An ordered division of organisms into categories
  based on a set of characteristics.
• Had 2 major contributions

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Squirrels
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Binomial Nomenclature

• Practice of using a 2 part scientific name for
  every species.
• First part is the genus name
• Second part is the species specific name
• Both words are in italics
• Genus name is capitalized
• ex. Homo sapien

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2. Hierarchical Classification
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Taxon

• Any named group at any level.
• However, grouping, especially at higher levels,
  is somewhat arbitrary.

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Creating Trees

• Cladograms
• Displays patterns of shared characteristics.
• Clade- a group of species that includes an
  ancestral species and all its descendants.

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Creating Trees

• What makes a valid clade?
• Monophyletic- an ancestral species and all its
  descendants (valid)

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Creating Trees

• Paraphyletic- ancestral species and some
  descendants (not valid- missing some info)

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Creating Trees

• Polyphyletic- has several species but not the
  ancestor (not valid- missing some info)

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Creating trees

• Shared primitive character- A character that
  extends beyond the taxon you are defining.
• Shared derived character- evolutionary novelty
  unique to a clade.

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Creating Trees

• Phylogenetic trees
• Phylogram- Like a cladogram BUT it also includes
  relative times of changes.

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Creating Trees

• Ultrametric Trees- Like a Phylogram BUT includes
  actual times of changes.

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Domains

• Three Domains
• Bacteria- Most prokaryotes
• Archae- The rest of the prokaryotes that live in
  a variety of environments
• Eukarya- All eukaryotes

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Universal Tree of Life

• 1. Last common ancestor of all things.
• 2. Possible fusion of bacterium and archaen,
  which led to eukaryotes.
• 3. Symbiosis with mitochondria
• 4. Symbiosis with chloroplast and the start of
  plants.