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Time Scales

Time Scales. Ecological Time - refers to time scales reflective of life spans of organisms and periods of environmental change (usually 0-100 years; can be expanded up to 10,000 years)

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Time Scales

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  1. Time Scales • Ecological Time - refers to time scales reflective of life spans of organisms and periods of environmental change (usually 0-100 years; can be expanded up to 10,000 years) • Geological Time - relates to the time frame over which geological processes occur (millions of years). Relevant to macroevolution

  2. Taxonomy • Linnaeus’ hierarchical system of classification reflects evolutionary relatedness • The farther down you go in a hierarchy (e.g., phylum class family), the more closely related members of that group • Groups at any level can be referred to as taxon (plural taxa)

  3. Now view the hierarchy a little differently

  4. Fig. 26.2

  5. Binomial System of Nomenclature • Two word name that is unique to a species • Ursus americanus • Ceanothus americanus • Not a species without both names

  6. Domains • Similarities evident (principle of continuity and signature principle) • Differences reflect evolutionary divergence (how long ago they split)

  7. Phylogeny • The evolutionary history of a species or a group of related species • Used to track the relatedness of organisms over geological time

  8. Morphology is an Important Part of Studying Phylogenies • Primitive characters - morphological features that are present in a recent species and are also found in an ancestral species • Derived characters - features present in a recent species but not in an ancestral species. Developed through evolution

  9. Morphological Phylogenies

  10. Phylogeny based on sequences encoding the protein cytochrome oxidase subunit II.

  11. Fig. 26.19 – Cladogram of eukaryotes

  12. A Mechanism for Diversification • Horizontal (or lateral) gene transfer • Transfer of genes between different species • Common between prokaryotes • Prokaryotes to eukaryotes • Eukaryote to eukaryote – less common

  13. See figure heading for more complete explanation

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