1 / 41

Tracing Phylogeny

Tracing Phylogeny. Phylogeny. Phylon = tribe, geny = genesis or origin The evolutionary history of a species or a group of related species. Phylogeny. Found in fossils and the fossil record. Fossils. Any preserved remnant or impression of a past organism. Types of Fossils.

giovanni
Download Presentation

Tracing Phylogeny

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. Tracing Phylogeny

  2. Phylogeny • Phylon = tribe, geny = genesis or origin • The evolutionary history of a species or a group of related species.

  3. Phylogeny • Found in fossils and the fossil record.

  4. Fossils • Any preserved remnant or impression of a past organism.

  5. Types of Fossils 1. Mineralized 2. Organic Matter 3. Trace 4. Amber

  6. Mineralized Fossils • Found in sedimentary rock. • Minerals replace cell contents. • Ex: bone, teeth, shells

  7. Organic Matter Fossils • Retain the original organic matter. • Ex: plant leaves trapped in shale. • Comment – can sometimes extract DNA from these fossils.

  8. Trace Fossils • Footprints and other impressions. No organic matter present.

  9. Amber • Fossil tree resin. • Preserve whole specimen. • Usually small insects etc.

  10. Fossils - Limitations • Rare event. • Hard to find . • Fragmentary. • Dating.

  11. Fossil Dating Methods 1. Relative - by a fossil's position in the strata relative to index fossils. 2. Absolute - approximate age on a scale of absolute time.

  12. Absolute - Methods 1. Radioactive 2. Isomer Ratios

  13. Radioactive • Estimated from half-life products in the fossil. • Ex: Carbon - 14 Potassium - 40

  14. What do fossils tell us? • That the geographical distribution of organisms has changed over time. • Reason? – The land formations of the earth have changed.

  15. Continental Drift • The movement of the earth's crustal plates over time. • Drift is correlated with events of mass extinctions and adaptive radiations of life.

  16. Pangaea • 250 million years ago. • One super continent. • Many life forms brought into contact with each other.

  17. Mesozoic era • Pangaea began to break up. • 180 million years ago.

  18. Result • Geographical Isolation. • New environments formed. • Old environments lost. • As the environments changed, so did Life.

  19. Example • Australian fauna and flora are unique. • Separated early and remained isolated for 50 million years.

  20. Mass Extinctions • The sudden loss of many species in geologic time. • May be caused by asteroid hits or other disasters.

  21. Examples • Permian Extinction • Cretaceous Extinction

  22. Permian Extinction • 250 million years ago. • 90% of species lost.

  23. Cretaceous Extinction • 65 million years ago. • Loss of the dinosaurs. • Good evidence that this event was caused by an asteroid that hit in the Yucatan, causing a “nuclear winter”.

  24. The crater

  25. Result of Mass Extinctions • Areas are open for the surviving species to exploit. • Rapid period of speciation (adaptive radiation). • Many new species are formed in a very short period of time.

  26. Convergent Evolution • When unrelated species have similar adaptations to a common environment. • Ex: Sharks and dolphins

  27. Only one is a cactus

  28. Need • Methods to group organisms by similarities and phylogenies.

  29. DNA Comparisons • A direct measure of common inheritance. • The more DNA in common, the more closely related.

  30. DNA Comparison Methods 1. DNA-DNA Hybridization 2. Restriction Mapping 3. DNA Sequencing All three methods have been used, but DNA Sequencing is becoming the most common.

  31. Protein Comparisons • Examines the Amino Acid sequence of homologous proteins. • Ex: Cytochrome C Study

  32. Schools of Taxonomy 1. Phenetics 2. Cladistics

  33. Phenetics • Makes no phylogenetic assumptions. • Taxonomic affinities based on measurable similarities. • Ex: Numerical Taxonomy

  34. Cladistics • Branch points defined by novel characteristics. • Branch pattern may not reflect evolutionary history.

  35. Cladistics

More Related