Aversive behavior of beaded lizard, Heloderma horridum, to sympatric and allopatric predator snakes

摘要

Twenty-two beaded lizards (Heloderma horridum) showed their capacity to discriminate chemical cues of 9 sympatric snakes (potential predators of lizards) and 6 allopatric snakes. The study demonstrated a previously unknown ability to recognize and avoid dangerous snakes by this helodermatid. Experiments revealed differences among escape latency (ESC) in 60-s trials for this behavior. Mean number of seconds +/-1 SD for Boa constrictor was 2.81 +/- 1.68, Loxocemus bicolor was 9.41 +/- 1.99, Crotalus basiliscus was 3.04 +/- 1.59, Agkistrodon bilinealus was 3.54 +/- 1.60, Drymarchon corais was 10.77 +/- 2.31, and Masticophis mentovarius was 16.05 +/- 2.17. Other sympatric snakes used as controls, Such as Micrurus distans, Timarphodon biscutatus, and Oxybelis aeneus, elicited no aversive behavior presumably because they do not feed on helodermatids. Experiments also showed antipredator behaviors were elicited by the allopatric snakes Charina trivirgata (16.27 +/- 1.88 s), Crotalus molossus (6.36 +/- 1.73 s), and C. triseriatus (52.09 +/- 2.31 s), but not by Micrurus limbatus, Pituophis deppei, or Pseudoelaphe flavirufa. We hypothesize that extension of this behaviour might involve phylogenetic relationship among sympatric and allopatric species of snakes in the same family. This behavioral response could have a pre-selective effect during geographical dispersion for some species like H. horridum.