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Gigantism and the Island Rule Tim Schmidt. Questions What caused the extinction of gigantism (Pleistocene megafauna)? What are the causes behind the island.

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Presentation on theme: "Gigantism and the Island Rule Tim Schmidt. Questions What caused the extinction of gigantism (Pleistocene megafauna)? What are the causes behind the island."— Presentation transcript:

1 Gigantism and the Island Rule Tim Schmidt

2 Questions What caused the extinction of gigantism (Pleistocene megafauna)? What are the causes behind the island rule? Is there a link between the extinction of gigantism in animals and the “island rule”?

3 Gigantism (Pleistocene megafauna) Mega Fauna = Big animal Pleistocene era ended around 12,000 years ago with recession of last continental glacier Environmental Changes Overhunting journal.davidbyrne.com

4 Megafauna vs. Humans (Barnosky, 2008)

5 Irish Elk Known for large antlers Used for fighting (Only in males) Antlers could reach 3.6 m and weigh almost 40 kg Change of environment led to lack of nutrients (Calcium) Could no longer afford antlers energetically Human hunting

6 Moose vs. Irish Elk (Moen, Pastor, & Cohen, 1999)

7 Island Rule Small vertebrates -  Gigantism Competitive Release Large vertebrates -  Dwarfism Lack of nutrition Increased competition New predators

8 Case Study (Lomolino, 2005)

9 Conclusion Similarities between Extinction of Megafauna and Island Rule o Both have nutritional constraints o New predator relationships o Increased competition

10 Works Cited Barnosky, A, D. (2008). Megafauna biomass tradeoff as a driver of quaternary and future extinctions. PNAS, 105(1), 11543– Lomolino, M.V. (1985). Body size of mammals on islands: the island rule reexamined. The American Naturalist, 125(2), Lomolino, M.V. (2005). Body size evolution in insular vertebrates: generality of the island rule. Journal of Biogeography, 32, McClain, C.R., Boyer, A.G., & Rosenberg, G. (2006). The island rule and the evolution of body size in the deep sea. Journal of Biogeography, 33, Meiri, S., Dayan, T., & Simberloff, D. (2004). Body size of insular carnivores: little support for the island rule. The American Naturalist, 163(3), Millien, V., & Damuth, J. (2004). Climate change and size evolution in an island rodent species: new perspectives on the island rule. Evolution, 58(6), Moen, R.A., Pastor, J., & Cohen, Y. (1999). Antler growth and extinction of irish elk. Evolutionary Ecology Research, 1, Raia, P., & Meiri, S. (2006). The island rule in large mammals: paleontology meets ecology. Evolution, 60(8),

11 Questions?


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