Turtles: a cause for wonder, a cause for concern Thomas Akre
Longwood University Farmville, VA
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The Tortoise and the Hare
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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
(18941973)
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Remarkable Defensive Armor E. S. Gaffney.
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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
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Survivors in Armor Millions of years agoThousands of Genera All
Genera Well-defined Genera Mass Extinctions Triassic
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Survivors in Armor
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Millions of years agoThousands of Genera All Genera
Well-defined Genera Mass Extinctions Cretaceous K-T
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Survivors in Armor
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Turtles in the Tree of Life Laurin & Gauthier 2009
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Turtle Relatives - Procolophonids Nycteroleter D. Bogdanov
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Turtle Relatives - Pareiasaurs E. Karkemish
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Turtles in the Tree of Life Modesto & Anderson 2004
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Turtle Relatives - Plesiosaurs Thalassiodracon hawkinsi N.
Tamura
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The First Turtle? Li et al. 2008 Odontochelys semitestacea M.
Donnelly
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The Earliest Turtles Li et al. 2008 C. Houck Proganochelys
quenstedti
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The Turtle Tree of Life Joyce & Gauthier 2004
Odontochelys
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Tortoise and Freshwater Turtle Species Richness by 12100 km 2
Grid Species Richness
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The Side-Neck Turtles Gaffney and Meylan 1988
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How to Protect Your Neck Pleurodire F. Ippolito.
Cryptodire
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The Side-Neck Turtles Pleurodires
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Tortoise and Freshwater Turtle Mean Root Distance by 12100 km 2
Grid Global Diversification
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Renous et al. 2008
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Meiolania: the Horned Turtle Gaffney and Meylan 1988
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Meiolania: Survivors in Armor Meiolania platyceps C. Houck F.
Ippolito.
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Oceanic Voyages Gerlach et al. 2006
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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
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General Model of Turtle Life-History Traits Low nest (clutch)
survivorshipLow nest (clutch) survivorship Low, but variable
juvenile survivorshipLow, but variable juvenile survivorship
Delayed sexual maturity (430 yrs)Delayed sexual maturity (430 yrs)
At a certain size the shell confers protection that leads to high
adult survivorship (often > 95%)At a certain size the shell
confers protection that leads to high adult survivorship (often
> 95%) Low annual reproductive output (fecundity)Low annual
reproductive output (fecundity) Repeated reproductive cycles
(extreme iteroparity)Repeated reproductive cycles (extreme
iteroparity) Long life-span (mean max. from 15200 yrs)Long
life-span (mean max. from 15200 yrs) Reduced or non-existent
senescenceReduced or non-existent senescence
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Delayed Maturity A. Teti Glyptemys muhlenbergii Loxodonta
africana
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The Whale in the Turtle Dermochelys coriacea C. Safina
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Mammalian Bone Growth Wyneken et al. 2008
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Giant Turtles R. Somma Stupendemys geographicus F. A. Lucas
Archelon ischryos
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Survival
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The Tongue of the Turtle Heiss et al. 2010
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The Fish in the Turtle
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Feeding
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A Buffer Against the Cold
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Temperature Dependent Sex Determination and Female Choice
Chrysemys picta M. JonesM. Marchand
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Nest Site Selection & Diapause Cann 1998
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Diapause and Aestivation
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Longevity
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Reproduction & Longevity Indeterminant Growth and
Experience Reproductive output, Nest Success & Hatchling
survivorship Cost of reproduction
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Turtles: a cause for concern commonplace objects were they
entirely extinct "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 (18941973)
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There is a Global Turtle Survival Crisis Habitat Loss
Unsustainable Use Disease
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Global Turtle Survival Crisis Invasive species Global Climate
Change Pollution
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Primary feeder markets of turtle imports into China have now
reached into India, New Guinea, Africa, and the United India, New
Guinea, Africa, and the UnitedStates
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Nearly half (42%) of the worlds 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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Discoveries, rediscoveries, and elevations
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Turtle Services They occupy a diverse array of ecological
niches and many species are considered to be critical components of
the ecosystems they inhabit M. Dorcas D. Scott
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R. Masroor
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Turtle Symbols
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Global Species Richness and Turtle Hotspots Tortoise and
Freshwater Turtle Species Richness by 12100 km 2 Grid
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Turtle Hotspots and Priority Areas Ganges-Brahmaputra Basin of
India and Bangladesh
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The Human Footprint
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58 species of five families in North America Turtle Priority
Areas