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Ecological release in White Sands lizards

Authors


  • Funded by the National Science Foundation (DEB-1054062 CAREER award to EBR and DBI-0939454 to the BEACON Center for the Study of Evolution in Action), the Natural Science and Engineering Research Council of Canada and the University of Idaho Student Grant Program to SDR.

S. Des Roches, Department of Biological Sciences, Life Sciences South 252, University of Idaho, P.O. Box 443051, Moscow, ID 83844-3051. Tel: (208) 885-6280; Fax: (208) 885-7905; E-mail: simone.desroches@gmail.com

Abstract

Ecological opportunity is any change that allows populations to escape selection from competition and predation. After encountering ecological opportunity, populations may experience ecological release: enlarged population size, broadened resource use, and/or increased morphological variation. We identified ecological opportunity and tested for ecological release in three lizard colonists of White Sands, New Mexico (Sceloporus undulatus, Holbrookia maculata, and Aspidoscelis inornata). First, we provide evidence for ecological opportunity by demonstrating reduced species richness and abundance of potential competitors and predators at White Sands relative to nearby dark soils habitats. Second, we characterize ecological release at White Sands by demonstrating density compensation in the three White Sands lizard species and expanded resource use in White Sands S. undulatus. Contrary to predictions from ecological release models, we observed directional trait change but not increased trait variation in S. undulatus. Our results suggest that ecological opportunity and ecological release can be identified in natural populations, especially those that have recently colonized isolated ecosystems.

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