1 / 21

Chapter 19

Organizing Information About Species: Taxonomy and Cladistics. Chapter 19.

kknapp
Download Presentation

Chapter 19

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Organizing Information About Species: Taxonomy and Cladistics Chapter 19 An unexpected family tree. What are the evolutionary relationships among a human, a mushroom, and a tulip? Molecular systematics has revealed that—despite appearances—animals, including humans, and fungi, such as mushrooms, are more closely related to each other than either are to plants.

  2. Phylogeny & Systematics • Phylogeny • evolutionary history of a species • based on common ancestries inferred from • fossil record • morphological & biochemical resemblances • molecular evidence • Systematics • connects classification system to phylogeny by categorizing & naming organisms

  3. Fossils

  4. Fossil record • Sedimentary rock are richest source of fossils • fossil record is a substantial, but incomplete, chronicle of evolutionary history • history of life on Earth is punctuated by mass extinctions 5000 year old ice mummy found on an Alpine ridge dividing Austria from Italy at 10,500 feet above sea level.

  5. Paleontology • Study of fossils • fossils provide the strongest evidence of change • links past & current organisms Woolly mammoth tusks

  6. Taxonomy • The science of naming and classifying species • Began thousands of years ago • Consistency in naming became important in 18th century

  7. Building phylogenies Two ways: Morphological & molecular homologies These are similarities based on shared ancestries Morphological homologies refer to body structures BUT you must… …Be beware of analogous structures Recall: convergent evolution

  8. How are molecular homologies evaluated? • Aligning DNA sequences • more bases in common = more closely related • analyzed by software beware of molecular homologies

  9. What is? Systematics • Connecting classification to phylogeny • A hierarchical system • Originated with CarolusLinnaeas • latin binomial • genus • species

  10. We make the connection by: Building trees • Connection between classification & phylogeny Tracing possible evolutionary relationships between some of the taxa of the order Carnivora, a branch of the class Mammalia.

  11. Illustration of phylogeny is done by making cladograms They show patterns of shared characteristics Classify organisms according to the order in time at which branches arise along a phylogenetic tree

  12. STOP AND BEGIN BUILDING YOUR CLADOGRAM!!!

  13. Molecular Systematics • Scientists who work in this area hypothesize phylogenies using molecular data • apply principle of parsimony • simplest explanation • fewest evolutionary events that explain data hypothetical bird species 3 possible phylogenies (there are more)

  14. Parsimony • Choose the “tree” that explains the data invoking the fewest number of evolutionary events

  15. Phylogenetic trees are hypotheses Which is the most parsimonious tree?

  16. Modern Systematics • Shaking up some trees! Crocodiles are now thought to be closer to birds than other reptiles

  17. Of Mice and Men… • Evolving genomes • now that we can compare the entire genomes of different organisms, we find… • humans & mice have 99% of their genes in common • 50% of human genes have a close match with those of yeast! • the simplest eukaryote

  18. Molecular clocks HIV-1M samples were collected from patients between early 1980s & late 1990s. The gene evolved at a relatively constant rate. Concluded that HIV-1M strain first infected humans in 1930s. Trace variations in genomes to date evolutionary changes Rate of change is calculated and then extrapolate back What does this assume?

  19. Universal Tree of Life • 3 Domains • Bacteria • Eukarya • Archaea

  20. Any Questions??

  21. Aaaaah… Structure-Function yet again!

More Related