Journal of Insect Behavior

, Volume 2, Issue 1, pp 105–121

Sexual selection at varying population densities in male field crickets,Gryllus veletis andG. pennsylvanicus

  • B. Wade French
  • William H. Cade

DOI: 10.1007/BF01053621

Cite this article as:
French, B.W. & Cade, W.H. J Insect Behav (1989) 2: 105. doi:10.1007/BF01053621


Male field crickets call and attract females or they silently search for females in the vicinity of calling males. At high population densities, fewer calling sites are available, defense of calling sites is costly, and an increased proportion of matings should result from searching behavior. To test these predictions, individually marked field crickets, Gryllus veletisand G. pennsylvanicus,were observed for 10 h nightly in large outdoor arenas at relatively high and low densities (20∶20 and 5∶5, males and females). Data were gathered on body weight, calling duration, movement, and mating frequency for individual crickets. These observations showed that variance in male mating success was significantly greater at a low density in G. pennsylvanicus,and calling duration correlated with mating success at this density. Direct selection on a trait was estimated as the partial regression coefficient (selection gradient, β′) and the total selection was estimated (direct and indirect selection on correlated traits) as the covariance (standardized intensity of selection, s′) of the trait on the relative mating success. Direct selection favored increased movement at a high density in G. veletis,and direct and total selection favored increased calling duration at a low density in G. pennsylvanicus.Most other comparisons were not statistically significant. The data are discussed in terms of density-dependent fluctuations in sexual selection on correlated male traits.

Key words

Gryllus sexual selection density dependence mating success acoustical signals alternative reproductive behavior searching behavior correlated traits Orthoptera Gryllidae 

Copyright information

© Plenum Publishing Corporation 1989

Authors and Affiliations

  • B. Wade French
    • 1
  • William H. Cade
    • 1
  1. 1.Department of Biological SciencesBrock UniversitySt. CatharinesCanada

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