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Contrast adaptive radiation vs. convergent evolution? Give an example of each.

Contrast adaptive radiation vs. convergent evolution? Give an example of each. What is the correct sequence from the most comprehensive to least comprehensive taxon ?

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Contrast adaptive radiation vs. convergent evolution? Give an example of each.

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  1. Contrast adaptive radiation vs. convergent evolution? Give an example of each. • What is the correct sequence from the most comprehensive to least comprehensive taxon? • In a population of 500 rabbits, 320 are homozygous dominant for brown coat color (BB), 160 are heterozygous (Bb), and 20 are homozygous white (bb). • What are the frequencies of the alleles (B and b)? • What are the frequencies of the different genotypes (BB, Bb, and bb)?

  2. Arrange these animals in a tree-like diagram that shows relatenessbased on this information: • Animal A: 4 chambered-heart (2 atria, 2 ventricles) • Animal B: 3-chambered heart (2 atria, 1 ventricle) • Animal C: muscular tube that pumps blood • Animal D: 2-chambered heart (1 atrium, 1 ventricle) • Animal E: 3-chambered heart (2 atria, 1 partially-divided ventricle) Who is most closely related to Animal A?

  3. Evolution of Heart Chambers in Animals Fish: 2-chambered heart Amphibians & Reptiles: 3-chambered heart Birds & Mammals: 4-chambered heart

  4. Chapter 20 Phylogeny

  5. Systematics: classifying organisms and determining their evolutionary relationships Taxonomy (classification) Systematics Phylogenetics (evolutionary history)

  6. Tools used to determine evolutionary relationships: • Fossils • Morphology (homologous structures) • Molecular evidence (DNA, amino acids) Who is more closely related? Animals and fungi are more closely related than either is to plants.

  7. Legless conditions evolved separately  analogous structures evolved by convergent evolution What kind of organism is this?

  8. Taxonomy: classifying and naming organisms Ordered division of organisms based on similar/different characteristics Dear King Philip Came Over For Good Spaghetti Each category at any level is called a taxon.

  9. Binomial nomenclature (Genus species) Naming system developed by Carolus Linnaeus

  10. Phylogenetic Tree • Branching diagram that shows evolutionary history of a group of organisms

  11. Branch lengths can represent genetic change

  12. Branch lengths can indicate time

  13. Various tree layouts Circular (rooted) tree Unrooted tree Rooted tree

  14. Constructing Phylogenetic Trees • Divergent vs. Convergent Evolution • Sorting homology from analogy

  15. Leopard Turtle Hair Salamander • Clade= group of species that includes an ancestral species + all descendents • Shared derived characteristics (evolutionary novelties) areused to construct cladograms Amniotic egg Tuna Four walking legs Lamprey Hinged jaws Lancelet (outgroup) Vertebral column • Shared ancestral characteristic (of all vertebrates) = vertebral column • Shared derived characteristic of mammals = hair Cladogram

  16. Constructing a phylogenetic tree A 0 indicates a character is absent; a 1 indicates that a character is present.

  17. Draw a phylogenetic tree based on the data below. Draw hatch marks on the tree to indicate the origin(s) of each of the 6 characters.

  18. Answer:

  19. Principle of maximum parsimony: use simplest explanation (fewest DNA changes) to construct phylogenetic tree – “keep it simple” The first tree is the most parsimonious  fewest changes in bases

  20. Molecular clocks: measure evolutionary change based on regions of genome that appear to evolve at constant rates • Estimate date of past evolutionary events • Eg. Origin of HIV infection in humans= 1930’s Molecular clock for mammals Origin of HIV-1 M

  21. Tree of Life 3 Domains: Bacteria, Archaea, Eukarya Based on sequence data for rRNA and other genes

  22. Common Ancestry of All Life Forms Elements conserved across all 3 domains: • DNA and RNA are carriers of genetic info • Universal genetic code (codons amino acids) • Conserved metabolic pathways

  23. Conserved elements in Eukaryotes: • Cytoskeleton • Membrane-bound organelles • Linear chromosomes • Endomembrane systems (including nuclear envelope)

  24. Horizontal Gene Transfer • Movement of genes between different domains • Exchange of transposable elements, plasmids, viral infections, fusion of organisms • Trees are complex! • Phylogenetic trees are hypotheses subject to change based on available data

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