1 / 31

How Diversity Evolves

How Diversity Evolves. Macroevolution. The evolution of large scale diversity Evolutionary novelties Wings, feathers, brain sizes Speciation: origin of new species. What is a species?. The morphological species concept: if it looks like a duck, and quacks like a duck…. What is a species?.

evelia
Download Presentation

How Diversity Evolves

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. How Diversity Evolves

  2. Macroevolution • The evolution of large scale diversity • Evolutionary novelties • Wings, feathers, brain sizes • Speciation: origin of new species

  3. What is a species? • The morphological species concept: if it looks like a duck, and quacks like a duck…

  4. What is a species? • The morphological species concept: Mature leaves of arrowhead plants (Sagittaria sagittifolia)

  5. What is a species? • The biological species concept: groups of interbreeding natural populations that are reproductively isolated from other such groups. • What problems might exist with this definition?

  6. What is Speciation? • For speciation to occur, populations must attain reproductive isolation. • Genetic Divergence: when populations become reproductively isolated.

  7. Reproductive Isolating Mechanisms • Any heritable features that prevent interbreeding between populations • Isolating mechanisms can be physical (body form), physiological (body function), or behavioral • Isolating mechanisms can be prezygotic or postzygotic. Note: a zygote is a fertilized egg.

  8. Reproductive Barriers

  9. Prezygotic Isolation • Temporal (reproduce at different times)

  10. Prezygotic Isolation • Behavioral (courting behaviors are different) Bird courtship behavior include visual, acoustic and tactile rituals that identify members of the same species.

  11. Prezygotic Isolation • Mechanical (differences in reproductive organs) • Plants and their pollinators

  12. Prezygotic Isolation • Habitat (same area but different habitats) • Microhabitats of Manzanita in Nevada

  13. Prezygotic Isolation • Gametic Mortality (egg & sperm incompatibility) Correct chemical signal needed for successful fertilization

  14. Postzygotic Isolation • If fertilization does occur the embryo is often weak and dies. • In others, hybrids are vigorous but sterile. Mules are produced by a male donkey and female horse.

  15. Mechanisms of Speciation • Allopatric speciation: geographically isolated by a physical barrier. • Sympatric speciation: species form within home range of an existing species.

  16. Allopatric Speciation • “allo” = different; “patric” = lands • Antelope squirrels and the Grand Canyon

  17. Evidence for Allopatric Speciation

  18. Allopatric Speciation • Archipelagos island chain and adaptive radiation • low competition and predation • abundant habitats and resources

  19. Sympatric Speciation • “sym” = together • Cichlids of Lake Barombi Mbo • Many species by feeding modes (open water, bottom feeders, shoal feeders)

  20. Sympatric Speciation • Polyploidy • How does this happen? • Improper separation during meiosis & mitosis • 50% of all flowering plants are polyploidy • Animal problems

  21. The Evolution of Wheat

  22. Evolutionary Trees and Rates of Change • Trees summarize information about the relationship among species over time. • Two types of models: • Gradual model: branches at slight angles to show slow changes over time • Punctuation model: horizontal branches show abrupt speciation followed by stable conditions

  23. Evolutionary Trees and Rates of Change

  24. Macroevolution and Exaptation • Biological novelties • Structures that evolved in one context becomes adapted for other functions

  25. Macroevolution and “Evo-Devo” • Genetic changes in developmental biology • Homeotic genes • Control timing, rate, and spatial patterns in embryos • Subtle changes can have profound effects • Paedomorphosis Axolotl

  26. “Evo-Devo” Research

  27. Macroevolution and Earth’s History

  28. Macroevolution and Historical Events

  29. Evolution Today?

More Related