Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Evolution of Escape Behavior Diversity

Jos. J. Schall and Eric R. Pianka
The American Naturalist
Vol. 115, No. 4 (Apr., 1980), pp. 551-566
Stable URL: http://www.jstor.org/stable/2460484
Page Count: 16
  • Read Online (Free)
  • Download ($19.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Evolution of Escape Behavior Diversity
Preview not available

Abstract

Predators which form search images or learn to predict prey escape behavior should be hindered by diverse prey morphologies and escape behaviors. Thus, among conspecific prey populations, escape tactic diversities should vary positively with predation pressure and escape tactics should diverge among similar sympatric species that share predators. Escape behaviors were quantified for whiptail lizards at sites with only one species (Cnemidophorus tigris) scattered over the western North American deserts and for an assemblage of five species of sympatric whiptails in southwestern Texas. Relative predation pressure was estimated by frequency of broken tails. Several factors confound use of this index; however, percent broken tails is correlated with actual density of potential whiptail predators seen at sites. Escape-behavior diversity is positively correlated with percent of tails broken at single-species sites and is also correlated with three estimates of predator abundance, although not significantly. These results also fit another hypothesis, namely, that lizards become wary after being attacked by a predator. However, lizards with broken tails are not more wary than unharmed lizards. Sympatric whiptail species differ significantly in escape behavior. Escape behaviors are more divergent than if each species evolved its escape tactics independently of others in a random fashion. Behaviors of each whiptail species are described; syntopic species frequently differ greatly in escape behaviors. However, differences among species in escape behaviors may be related to differences in microhabitat selection, a possibility that is difficult to discount. Cnemidophorus tigris in southwestern Texas has a reduced frequency of broken tails compared with populations at more westerly sites where this species occurs without congeners but with presumed similar predation pressures, perhaps as a result of the protection offered by the assemblage of species with diverse escape behaviors.

Page Thumbnails

  • Thumbnail: Page 
551
    551
  • Thumbnail: Page 
552
    552
  • Thumbnail: Page 
553
    553
  • Thumbnail: Page 
554
    554
  • Thumbnail: Page 
555
    555
  • Thumbnail: Page 
556
    556
  • Thumbnail: Page 
557
    557
  • Thumbnail: Page 
558
    558
  • Thumbnail: Page 
559
    559
  • Thumbnail: Page 
560
    560
  • Thumbnail: Page 
561
    561
  • Thumbnail: Page 
562
    562
  • Thumbnail: Page 
563
    563
  • Thumbnail: Page 
564
    564
  • Thumbnail: Page 
565
    565
  • Thumbnail: Page 
566
    566