1. Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, Texas 77843‐2258;2. Section of Integrative Biology C0930, School of Life Sciences, University of Texas, Austin, Texas 78712‐1064;3. Sam Noble Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, Norman, Oklahoma 73072‐7029;4. School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588‐0118