Behavioral Ecology and Sociobiology

, Volume 14, Issue 1, pp 69–76 | Cite as

Advantages and a disadvantage of large size for male gammarus pulex (Crustacea: Amphipoda)

  • Paul I. Ward


The breeding system of the freshwater amphipod Gammarus pulex includes a precopulatory guarding phase by a male. The length of this guarding phase is investigated with respect to a male's size and the number and size of his competitors. As the absolute number of competitors increases, so does the guarding time but as the absolute number of available females increases, the guarding time decreases. Takeovers of the females by unpaired males are more frequent in longer precopulas (Table 2). In contests for females, larger males have two advantages over smaller males; they are better able to make a takeover (Table 2) and better able to resist takeover attempts while paired (Table 3). Males increase the length of the guarding phase as the mean size of their competitors increases (Table 4). When not paired males are usually searching for available females, perhaps in the stream current. Females are unaffected by current speed but increasing current causes decreased male survivorship (Table 5) and increased precopula duration (Table 5). Searching in currents is more dangerous for larger males than smaller ones. It is proposed that the male size distribution observed is the result of selection pressure to increase size from male-male competition balanced by selection against large size while searching for females in the current.


Selection Pressure Absolute Number Current Speed Breeding System Large Male 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alcock J, Jones CE, Buckman SL (1977) Male nesting strategies in the bee Centris pallida Fox (Anthophoridae; Hymenoptera). Am Nat 111:145–155Google Scholar
  2. Birkhead TR, Clarkson K (1980) Mate selection and precopulatory guarding in Gammarus pulex. Z Tierpsychol 52:365–380Google Scholar
  3. Borgia G (1981) Mate selection in the fly Scatophaga stercoraria: female choice in a male-controlled system. Anim Behav 29:71–80Google Scholar
  4. Davies NB, Halliday TR (1977) Optimal mate selection in the toad Bufo bufo. Nature 269:56–58Google Scholar
  5. Dennert HG (1974) Tolerance differences and interspecific competition in three members of the amphipod genus Gammarus. Bijdr Dierkd 44:83–99Google Scholar
  6. Gee JHR (1982) Resource utilization by Gammarus pulex (Amphipoda) in a Cotswold stream: a microdistribution study. J Anim Ecol 51:817–832Google Scholar
  7. Grafen A, Ridley M (1983) A model of mate guarding. J Theor Biol 102:549–567Google Scholar
  8. Hughes RV (1979) Precopula in Gammarus pulex. Unpublished Ph D thesis, University of LiverpoolGoogle Scholar
  9. Hynes HBN (1955) The reproductive cycle of some British freshwater Gammaridae. J Anim Ecol 24:352–387Google Scholar
  10. Hynes HBN (1970) The ecology of running waters. Liverpool University Press, LiverpoolGoogle Scholar
  11. Kim J-O, Kohout FJ (1975) Multiple regression analysis: subprogram regression. In: Nie NH, Hull CH, Jenkins JG, Steinbrenner K, Bent DH (eds) Statistical package for the social sciences. McGraw-Hill, New YorkGoogle Scholar
  12. Manning JT (1975) Male discrimination and investment in Asellus aquaticus (L.) and A. meridianus Racovitsza (Crustacea: Isopoda). Behaviour 55:1–14Google Scholar
  13. Maynard Smith J (1982) Evolution and the theory of games. Cambridge University Press, CambridgeGoogle Scholar
  14. Parker GA (1982) Phenotype-limited evolutionarily stable strategies. In: King's College Sociobiology Group (eds) Current problems in sociobiology. Cambridge University Press, CambridgeGoogle Scholar
  15. Partridge L, Farquhar M (in press) Lifetime mating success of male fruitflies (Drosophila melanogaster) is related to their size. Anim BehavGoogle Scholar
  16. Ridley M, Thompson DJ (1979) Size and mating in Asellus aquaticus (Crustacea: Isopoda). Z Tierpsychol 51:380–397Google Scholar
  17. Sutcliffe DW, Carrick TR, Willoughby LG (1981) Effects of diet, body size, age and temperature on growth rates in the amphipod Gammarus pulex. Freshwater Biol 11:183–214Google Scholar
  18. Ward PI (in press) The effects of size on the mating decisions of Gammarus pulex. (Crustacea: Amphipoda). Z TierpsycholGoogle Scholar

Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • Paul I. Ward
    • 1
  1. 1.Department of ZoologyUniversity of LiverpoolLiverpoolEngland

Personalised recommendations