1 / 98

Biogeography of Island Faunas: Patterns, Isolation, and Convergence

Explore the unique biogeography of island faunas, examining the correlation between isolation and species uniqueness, the dominance of dispersive forms, and the variation within and between species. Learn about the observations made by Charles Darwin during his voyage of the Beagle and his contributions to the understanding of how change occurs.

williamward
Download Presentation

Biogeography of Island Faunas: Patterns, Isolation, and Convergence

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. Argentina Australia C. Observations 4. Biogeography - Community Convergence In similar environments, there are organisms that fill similar ecological roles – and they are morphologically similar. Correlated patterns…

  2. C. Observations 4. Biogeography – Island Faunas

  3. C. Observations 4. Biogeography – Island Fauna - Fauklands – species same as mainland - Galapagos – species different from mainland a. degree of isolation correlated with uniqueness of inhabitants…..

  4. Voyage of the Beagle – Darwin (1845) "The natural history of these islands is eminently curious, and well deserves attention. Most of the organic productions are aboriginal creations, found nowhere else; Flightless Cormorant

  5. “…there is even a difference between the inhabitants of the different islands; yet all show a marked relationship with those of America, though separated from that continent by an open space of ocean, between 500 and 600 miles in width.” Green Iguana – Central and South America

  6. “…The archipelago is a little world within itself, or rather a satellite attached to America, whence it has derived a few stray colonists, and has received the general character of its indigenous productions. Considering the small size of the islands, we feel the more astonished at the number of their aboriginal beings, and at their confined range.” Galapagos Land Iguana, pallid species, only on Santa Fe island.

  7. “… Seeing every height crowned with its crater, and the boundaries of most of the lava streams still distinct, we are led to believe that within a period geologically recent the unbroken ocean was here spread out.”

  8. “…Hence, both in space and time, we seem to be brought somewhat near to that great fact -- that mystery of mysteries -- the first appearance of new beings on this earth.” The Voyage of the Beagle – Charles Darwin

  9. C. Observations 4. Biogeography – Island Faunas a. Isolation correlates with uniqueness

  10. C. Observations 4. Biogeography – Island Faunas a. Isolation correlates with uniqueness b. islands are dominated by dispersive forms

  11. C. Observations 4. Biogeography – Island Faunas a. Isolation correlates with uniqueness b. islands are dominated by dispersive forms c. there is even variation among islands

  12. - Finches

  13. "Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends."

  14. - Mockingbirds

  15. - Mockingbirds Darwin classified four varieties of one species: One species

  16. - Mockingbirds John Gould, the premiere ornithologist of the day, classified these as four species:

  17. - Mockingbirds Darwin began to think… could the variation WITHIN species eventually lead to variation BETWEEN species? Could organisms in a species become so different that they become different species?

  18. C. Observations 4. Biogeography – Island Faunas - How did these animals get here? Everything points to migration from Americas

  19. C. Observations 4. Biogeography – Island Faunas - How did these animals get here? Everything points to migration - But if ancestors migrated from Americas,

  20. C. Observations 4. Biogeography – Island Faunas - How did these animals get here? Everything points to migration - But if ancestors migrated from Americas, then the species must have changed over time into the species we observe there today…. Because they are not the same.

  21. C. Observations 5. Argument for Evolution as Historical Fact: P1: Species that are alive today are different from those that have lived previously. P2: Spontaneous Generation is refuted, so organisms only come from other organisms. C1: Thus, the organisms alive today must have come from those pre-existing, yet different, species. C2: There must have been change through time (evolution). Corollary: The fossil record, vestigial organs, and homologies are all explicable and logical in this context, and inexplicable (even heritical) in some theological contexts (imperfection).

  22. I. Darwin’s Contributions A. His Life B. Origin of Species C. Observations D. Hypothesis – How Change Occurs

  23. D. Hypothesis – How Change Occurs 1. Transitional Observations a. Domesticated Animals

  24. D. Hypothesis – How Change Occurs 1. Transitional Observations a. Domesticated Animals

  25. D. Hypothesis – How Change Occurs 1. Transitional Observations a. Domesticated Animals Humans can change the characteristics of a species by ‘selecting’ for particular traits. This can lead to the expression of extreme variation, well beyond the original range of variation in the initial group. Selection can create…. There are no wolves that are as small as Chihuahuas…

  26. D. Hypothesis – How Change Occurs 1. Transitional Observations b. 1844: Darwin Reads Malthus - EssayOn the Principle of Population (1798) Thomas Malthus (1766-1834)

  27. D. Hypothesis – How Change Occurs 1. Transitional Observations b. 1844: Darwin Reads Malthus - EssayOn Population P1: All populations have the capacity to ‘over-reproduce’ P2: Resources are finite C: There will be a “struggle for existence”… most offspring born will die before reaching reproductive age.

  28. D. Hypothesis – How Change Occurs 2. Natural Selection P1: All populations have the capacity to ‘over-reproduce’ P2: Resources are finite C: There will be a “struggle for existence” P3: Organisms in a population vary, and some of this variation is heritable

  29. D. Hypothesis – How Change Occurs 2. Natural Selection P1: All populations have the capacity to ‘over-reproduce’ P2: Resources are finite C: There will be a “struggle for existence” P3: Organisms in a population vary, and some of this variation is heritable C2: Some organisms, as a consequence of their inherited traits, will be more likely to survive and reproduce than others. There will be “differential reproductive success.”

  30. D. Hypothesis – How Change Occurs 2. Natural Selection C2: Some organisms, as a consequence of their inherited traits, will be more likely to survive and reproduce than others. There will be “differential reproductive success.” C3: So, adaptive traits will be passed on in a population at higher frequency than less adaptive traits. These adaptive traits will accumulate in a population. The population will change over time. LINEAGE EVOLUTION.

  31. D. Hypothesis – How Change Occurs 2. Natural Selection C2: Some organisms, as a consequence of their inherited traits, will be more likely to survive and reproduce than others. There will be “differential reproductive success.” C3: Over time, adaptive traits will be passed on in a population at higher frequency than less adaptive traits. These adaptive traits will accumulate in a population. The population will change over time. LINEAGE EVOLUTION. Corollary: Two populations, adapting to different environments, will become different from one another; perhaps so different that they are unable to mate, and are different species RADIATIONAL EVOLUTION.

  32. E. Dilemmas 1. Evolution of complex traits

  33. E. Dilemmas 1. Evolution of complex traits

  34. E. Dilemmas 1. Evolution of complex traits - "we should be extremely cautious in concluding that an organ could not have been formed by transitional gradations of some kind. Numerous cases could be given in the lower animals of organs performing at the same time wholly distinct functions"

  35. E. Dilemmas 1. Evolution of complex traits 2. Where are the continuous sequences of transitional forms, both through time and at present (connecting existing species?) X X X X ? X X X X X

  36. E. Dilemmas • 1. Evolution of complex traits • 2. Where are the continuous sequences of transitional forms? • the fossil record is incomplete – not all species leave a fossil • Keep looking…

  37. E. Dilemmas 1. Evolution of complex traits 2. Where are the continuous sequences of transitional forms? 1861: Archeopteryx Lithographica

  38. E. Dilemmas 1. Evolution of complex traits 2. Where are the continuous sequences of transitional forms? - Connecting species: Adapted forms swamp intermediates, which are typically rare and are not as 'perfected' as adapted forms...

  39. E. Dilemmas 1. Evolution of complex traits 2. Where are the continuous sequences of transitional forms? 3. How are instincts evolved?

More Related