Yet coyotes can be opportunistic hunters with changing prey-killing behaviors because of their intermediate size and adaptability. In contrast, coyotes are usually solitary predators of small mammals, such as rodents and rabbits. Wolves are large-prey specialists that hunt in packs by means of a long, enduring chase. "This study provides evidence that interactions among carnivores and their prey are the probable cause of evolutionary change in coyotes." "In a time of increasing loss of biodiversity, understanding the degree to which species interactions drive evolutionary change is important," says Saran Twombly, program director in NSF's Division of Environmental Biology, which supported the research. orcutti was more carnivorous than modern coyotes. Pleistocene coyotes also had wider teeth for processing meat-an adaptation for killing larger prey and dealing with higher stresses during food acquisition and processing. orcutti were significantly thicker and deeper than those of recent populations. They found few differences between Pleistocene and Holocene wolf populations.Ĭoyotes in the Pleistocene ( Canis latrans orcutti) were distinct from existing coyotes, however. They also measured the skeletons of wolves ( Canis lupus) and coyotes ( Canis latrans) from Pleistocene-aged tar deposits, as well as of early, mid-, and recent Holocene (end of the Pleistocene to the present) populations of both. To find out if this could be the case, the scientists examined body size in living coyotes across different climates from North Dakota to southern California. They hypothesized that perhaps species interactions, or lack thereof, caused the shift. The researchers then took another approach. Surprisingly, however, coyotes don't show a correlation between climate and body size. Meachen and Samuels began searching for the answer for these changes in appearance by looking at an ecogeographic principle called Bergmann's rule, which states that as climate gets colder, or as one moves farther away from the equator, animals get bigger. Gray wolves usually weigh 80 to 120 pounds coyotes, in comparison, weigh a mere 30 to 40 pounds. Today's gray wolf is five to six feet from nose-to-tail modern-day coyotes measure three to four feet. The journal Proceedings of the National Academy of Sciences published the results this week. Changes in body size occurred for coyotes because large prey and their large competitors were disappearing, the researchers find. When the last ice age ended more than 10,000 years ago, many large species of mammals went extinct and others underwent changes in appearance.īut what caused evolutionary changes to take place in the mammals that remained alive?Ī study by Julie Meachen of the National Science Foundation (NSF) National Evolutionary Synthesis Center and Josh Samuels of the John Day Fossil Beds National Monument reveals that gray wolves and coyotes, once more similar in size, took the extinction in different strides.Ĭoyotes changed from large, pack-hunting dogs to the smaller canines we know today and wolves essentially remained the same. Telephone numbers or other contact information mayīe out of date please see current contact information at media This material is available primarily for archival Office of Small and Disadvantaged Business Utilization (OSDBU)Ī young modern coyote looking at a fossil coyote skull in a southern California tar pit.National Center for Science and Engineering Statistics (NCSES).Award Statistics (Budget Internet Info System).Proposal and Award Policies and Procedures Guide (PAPPG).Responsible and Ethical Conduct of Research.Technology, Innovation and Partnerships (TIP).Social, Behavioral and Economic Sciences (SBE).Mathematical and Physical Sciences (MPS).International Science and Engineering (OISE).Environmental Research and Education (ERE).Computer and Information Science and Engineering (CISE).
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