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Turtles: a cause for wonder, a cause for concern

Turtles: a cause for wonder, a cause for concern. Thomas Akre Longwood University Farmville, VA. The Tortoise and the Hare. Turtles: a cause for wonder.

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Turtles: a cause for wonder, a cause for concern

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  1. Turtles: a cause for wonder, a cause for concern Thomas Akre Longwood University Farmville, VA

  2. The Tortoise and the Hare

  3. Turtles: a cause for wonder • "Because they are still living, turtles are commonplace objects to us: were they entirely extinct, their shells – the most remarkable defensive armor ever assumed by a tetrapod – would be a cause for wonder." Alfred Sherwood Romer (1894–1973)

  4. Remarkable Defensive Armor E. S. Gaffney.

  5. Survivors in Armor • Turtles (Order Testudines) are a unique (monophyletic) and highly divergent lineage • They have existed nearly unchanged for at least 210 million years and survived the last great mass extinction 65 mya

  6. Survivors in Armor All Genera Well-defined Genera Mass Extinctions Triassic Millions of years ago Thousands of Genera

  7. Survivors in Armor

  8. Survivors in Armor All Genera Well-defined Genera Cretaceous “K-T” Mass Extinctions Millions of years ago Thousands of Genera

  9. Survivors in Armor

  10. Turtles in the Tree of Life Laurin & Gauthier 2009

  11. Turtle Relatives - Procolophonids Nycteroleter D. Bogdanov

  12. Turtle Relatives - Pareiasaurs E. Karkemish

  13. Turtles in the Tree of Life Modesto & Anderson 2004

  14. Turtle Relatives - Plesiosaurs Thalassiodracon hawkinsi N. Tamura

  15. The First Turtle? Odontochelys semitestacea Li et al. 2008 M. Donnelly

  16. The Earliest Turtles Proganochelys quenstedti C. Houck Li et al. 2008

  17. The Turtle Tree of Life Odontochelys Joyce & Gauthier 2004

  18. Species Richness Tortoise and Freshwater Turtle Species Richness by 12100 km2 Grid

  19. The Side-Neck Turtles Gaffney and Meylan 1988

  20. How to Protect Your Neck F. Ippolito. Pleurodire Cryptodire

  21. The Side-Neck Turtles • Pleurodires

  22. Global Diversification Tortoise and Freshwater Turtle Mean Root Distance by 12100 km2 Grid

  23. Renous et al. 2008

  24. Meiolania: the Horned Turtle Gaffney and Meylan 1988

  25. Meiolania: Survivors in Armor Meiolania platyceps F. Ippolito. C. Houck

  26. Oceanic Voyages Gerlach et al. 2006

  27. So what is a turtle and what does it mean to be a turtle? • In general, turtles have a suite of co-evolved life history characteristics that make them vulnerable to the effects of human encroachment • Life history theory and evidence from long-term population studies suggest that turtles live so long because they are bet-hedgers; they have adapted to environments with unpredictable juvenile survivorship

  28. General Model of Turtle Life-History Traits • Low nest (clutch) survivorship • Low, but variable juvenile survivorship • Delayed sexual maturity (4–30 yrs) • At a certain size the shell confers protection that leads to high adult survivorship (often > 95%) • Low annual reproductive output (fecundity) • Repeated reproductive cycles (extreme iteroparity) • Long life-span (mean max. from 15–200 yrs) • Reduced or non-existent senescence

  29. Delayed Maturity Loxodonta africana Glyptemys muhlenbergii A. Teti

  30. The Whale in the Turtle Dermochelys coriacea C. Safina

  31. “Mammalian” Bone Growth Wyneken et al. 2008

  32. Giant Turtles Archelon ischryos Stupendemys geographicus F. A. Lucas R. Somma

  33. Survival

  34. The Tongue of the Turtle Heiss et al. 2010

  35. The Fish in the Turtle

  36. Feeding

  37. A Buffer Against the Cold

  38. Temperature Dependent Sex Determination and Female Choice Chrysemys picta M. Marchand M. Jones

  39. Cann 1998 Nest Site Selection & Diapause

  40. Diapause and Aestivation

  41. Longevity

  42. Reproduction & Longevity • Indeterminant Growth and Experience Reproductive output, Nest Success & Hatchling survivorship Cost of reproduction

  43. Turtles: a cause for concern • "Because they are still living, turtles are commonplace objects to us: were they entirely extinct, their shells – the most remarkable defensive armor ever assumed by a tetrapod – would be a cause for wonder." Alfred Sherwood Romer (1894–1973)

  44. Disease Habitat Loss Unsustainable Use There is a Global Turtle Survival Crisis

  45. Global Climate Change Pollution Invasive species • Global Turtle Survival Crisis

  46. Primary feeder markets of turtle imports into China… …have now reached into India, New Guinea, Africa, and the United States

  47. Nearly half (42%) of the world’s tortoise and freshwater turtle species are threatened with extinction At least 70 species (± 25%) are poised on the brink of extinction

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