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Article Summary - Meachen, J. A. & Samuels, J. X. (2012), Evolution in Coyotes (Canis Latrans) in Response to the Megafaunal Extinctions.

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Introduction

Article Summary Meachen, J. A. & Samuels, J. X. (2012), Evolution in Coyotes (Canis Latrans) in Response to the Megafaunal Extinctions. Proceedings of the National Academy of Sciences of the United States of America. Vol. 109, no. 11, 4191-4196. It can be theorized that the evolutionary changes that a species undergoes throughout the history of its existence, as well as the divergence of new species and subspecies, can be attributed to a range of different factors, both biotic and abiotic. Meachen and Samuel's research delves into the evolutionary changes in the size of the coyote (Canis Latrans) throughout the Pleistocene and Holocene eras, up to the extant coyote populations. Meachen and Samuel explore the biotic factors that may have contributed to the evolutionary changes during this time, and they present evidence that shows why it was probably not the abiotic factors, such as climate change, that spurred these evolutionary changes. Meachen and Samuels also studied the evolutionary changes of the grey wolf (Canis Lupus) ...read more.

Middle

Meachen and Samuels compared the bone sizes against mean annual temperatures of the areas in which they originated and found that there was no correlation, for coyotes and wolves, with the increase or decrease in temperature. This suggests that coyotes do not follow Bergmann's law and that climate change was not the primary force behind the evolutionary changes. This complied with Meachen and Samuels' initial postulate because it shows that the evolutionary changes were most likely attributable to biotic factors. For the purpose of the their research, the biotic factors that Meachen and Samuels examined were competition and predator/prey interactions. There was a large morphological shift in the coyote that aligned with major megafaunal extinctions at the end of the Pleistocene era. The prey base for coyotes prior to these events consisted of larger mammals and ungulates, including horses, bison, camels, llama, and bison. This prey base required a larger more robust body size and stronger canine teeth, and craniums. ...read more.

Conclusion

This seems to be a negative conclusion, in that they do not explicitly present what is, but rather, what is not. Obviously, when it come to evolutionary development, it is near impossible to make definitive conlcusions due to the difficulty of archiving extensive, or complete, fossil records, and due to the fact that many factors are estimated, approximated, or hypothesized. For example, the effect of climate change was not supported due to the lack of correlation between extant coyote sizes and the temperatures of their habitats. However, predictions on the climate and habitats during the Pleistocene and Holocene eras cannot be completely accurate. 1 Nowak RM (1979) University of Kansas Museum of Natural History Monograph: North American Quaternary Canis (University of Kansas Museum of Natural History, Lawrence, KS), pp 1-154. 2 Merriam JC (1912) The fauna of Rancho La Brea, part II, Canidae. Memoirs of the University of California 1:215-272. 3 Arjo WM, Pletscher DH (1999) Behavioral responses of coyotes to wolf recolonization in northwestern Montana. Can J Zool 77:1919-1927 ?? ?? ?? ?? Juliette Dottle Biodiversity March 27th, 2012 ...read more.

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