SEXUAL dimorphism in body size is widespread in the animal kingdom. Whereas male giantism has been studied and explained extensively1,2, male dwarfism has not. Yet it is neither rare3–7 nor without theoretical interest8,9. Here we provide experimental and comparative data on spiders to support the theory that dwarf males are associated with high differential adult mortality, with males at much greater risk. Species with sedentary (low-risk) females have dwarf, roving (high-risk) males. Life-history theory could readily explain dwarfing if juvenile, but not adult, male mortality were large. We present a new model in which high mortality of searching mature males reduces the adult sex ratio (males: females), relaxing male–male competition and reducing the importance of male body size to favour dwarfing by early maturation. Early maturity also reduces male juvenile mortality and thus opposes adult mortality. This provides a mechanism that buffers skews in adult sex ratio and which is quite distinct from Fisher's principle10 and allied mechanisms9,11 for the primary sex ratio.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Cunningham, J. T. Sexual Dimorphism in the Animal Kingdom (Black, London, 1900).
Hendrick, A. V. & Temeles, E. J. Trends Ecol. Evol. 4, 136–139 (1989).
Gerhardt, U. Zool, Anz. 86, 80–82 (1930).
Elgar, M. A., Ghaffar, N. & Read, A. J. Zool. 222, 455–470 (1990).
Darwin, C. A. Monograph on the Cirripedia (Royal Society, London, 1851).
Kaestner, A. Invertebrate Zoology Vol. 2 (Wiley, New York, 1967).
Regan, C. T. Proc, R. Soc. B97, 386–399 (1925).
Darwin, C. The Descent of Man and Selection in Relation to Sex 2nd edn (Murray, London, 1894).
Ghiselin, M. T. The Economy of Nature and the Evolution of Sex (University of California Press. Berkeley, 1974).
Fisher, R. A. The Genetical Theory of Natural Selection (Oxford University Press. 1930).
Hamilton, W. D. Science 156, 477–488 (1967).
Vollrath, F. Z. Tierpsychol. 53, 61–78 (1980).
Pagel, M. D. & Harvey, P. H. Q. Rev. Biol. 63, 413–440 (1988).
Christenson, T. E. in Contemporary Issues in Comparative Psychology (ed. Dewsbury, D. A.) 149–174 (Sinaur, Sunderland, Massachusetts, 1990).
Vollrath, F. in Ecophysiology of Spiders (ed. Nentwig, W.) 357–370 (Springer, Berlin, 1987).
Newman, J. A. & Elgar, M. A. Am. Nat. 138, 1372–1395 (1991).
Gertsch, W. J. American Spiders (Van Nostrad, New York, 1949).
Levi, H. W. J. New York ent. Soc. 58, 59–91 (1955).
Watson, P. J. Behavl Ecol. Sociobiol. 26, 77–90 (1990).
Gunnarson, B. J. Zool. 217, 1–7 (1989).
Clutton-Brock, T. The Evolution of Parental Care (Princeton University Press, 1991).
Emlen, S. T. & Oring, L. W. Science 197, 215–223 (1977).
Parker, G. A. J. Fish. Biol. (in the press).
Maynard Smith, J. Evolution and the Theory of Games (Cambridge University Press, 1982).
Clutton-Brock, T. & Parker, G. A. Q. Rev. Biol. (in the press).
Smith, G. Fauna Flora Golf. Neapel 29, 1–123 (1906).
Caullery, M. Mitt. zool. Stn Neapel 18, 583–643 (1908).
Bertelsen, E. Dana Rep. 39, 1–176 (1951).
Beebe, W. Zoologica 6, 149–241 (1934).
Lockett, G. H. & Millidge, A. F. British Spiders Vol. 1 (Royal Society, London, 1951).
Lockett, G. H. & Millindge, A. F. British Spiders (Royal Society, London, 1953).
Shinkai, E. & Takano, S. Spiders of Japan (Tokai University Press, 1984).
Koh, J. K. H. A Guide to Common Singapore Spiders (Singapore Science Centre, 1989).
Mascord, R. Australian Spiders (Reed, Wellington, New Zealand, 1970).
About this article
Cite this article
Vollrath, F., Parker, G. Sexual dimorphism and distorted sex ratios in spiders. Nature 360, 156–159 (1992). https://doi.org/10.1038/360156a0
Annual Review of Entomology (2020)
Evolution Letters (2020)
Natural history of the ogre-faced spider Deinopis cf. cylindracea (Araneae: Deinopidae): revealing its phenology
Studies on Neotropical Fauna and Environment (2020)
Ecophysiological determinants of sexual size dimorphism: integrating growth trajectories, environmental conditions, and metabolic rates
Animal Behaviour (2019)