Nature Publishing Group, publisher of Nature, and other science journals and reference works
Nature
my account e-alerts subscribe register
   
Sunday 28 May 2017
Journal Home
Current Issue
AOP
Archive
Download PDF
References
Export citation
Export references
Send to a friend
More articles like this

Letters to Nature
Nature 360, 156 - 159 (12 November 1992); doi:10.1038/360156a0

Sexual dimorphism and distorted sex ratios in spiders

Fritz Vollrath* & Geoff A. Parker

* Department of Zoology, University of Oxford, Oxford 0X1 3PS, UK; Zoologisches Institut, Rheinsprung 9, CH 4051 Basel, Switzerland; Smithsonian Tropical Research Institute, Box 20272, Balboa, Panama
Department of Environmental and Evolutionary Biology, University of Liverpool, Liverpool L69 3BX, UK

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.

------------------

References

1. Cunningham, J. T. Sexual Dimorphism in the Animal Kingdom (Black, London, 1900).
2. Hendrick, A. V. & Temeles, E. J. Trends Ecol. Evol. 4, 136−139 (1989).
3. Gerhardt, U. Zool, Anz. 86, 80−82 (1930).
4. Elgar, M. A., Ghaffar, N. & Read, A. J. Zool. 222, 455−470 (1990).
5. Darwin, C. A. Monograph on the Cirripedia (Royal Society, London, 1851).
6. Kaestner, A. Invertebrate Zoology Vol. 2 (Wiley, New York, 1967).
7. Regan, C. T. Proc, R. Soc. B97, 386−399 (1925).
8. Darwin, C. The Descent of Man and Selection in Relation to Sex 2nd edn (Murray, London, 1894).
9. Ghiselin, M. T. The Economy of Nature and the Evolution of Sex (University of California Press. Berkeley, 1974).
10. Fisher, R. A. The Genetical Theory of Natural Selection (Oxford University Press. 1930).
11. Hamilton, W. D. Science 156, 477−488 (1967). | PubMed | ISI | ChemPort |
12. Vollrath, F. Z. Tierpsychol. 53, 61−78 (1980).
13. Pagel, M. D. & Harvey, P. H. Q. Rev. Biol. 63, 413−440 (1988). | Article | PubMed | ChemPort |
14. Christenson, T. E. in Contemporary Issues in Comparative Psychology (ed. Dewsbury, D. A.) 149−174 (Sinaur, Sunderland, Massachusetts, 1990).
15. Vollrath, F. in Ecophysiology of Spiders (ed. Nentwig, W.) 357−370 (Springer, Berlin, 1987).
16. Newman, J. A. & Elgar, M. A. Am. Nat. 138, 1372−1395 (1991). | Article |
17. Gertsch, W. J. American Spiders (Van Nostrad, New York, 1949).
18. Levi, H. W. J. New York ent. Soc. 58, 59−91 (1955).
19. Watson, P. J. Behavl Ecol. Sociobiol. 26, 77−90 (1990).
20. Gunnarson, B. J. Zool. 217, 1−7 (1989).
21. Clutton-Brock, T. The Evolution of Parental Care (Princeton University Press, 1991).
22. Emlen, S. T. & Oring, L. W. Science 197, 215−223 (1977). | PubMed | ISI | ChemPort |
23. Parker, G. A. J. Fish. Biol. (in the press).
24. Maynard Smith, J. Evolution and the Theory of Games (Cambridge University Press, 1982).
25. Clutton-Brock, T. & Parker, G. A. Q. Rev. Biol. (in the press).
26. Smith, G. Fauna Flora Golf. Neapel 29, 1−123 (1906).
27. Caullery, M. Mitt. zool. Stn Neapel 18, 583−643 (1908).
28. Bertelsen, E. Dana Rep. 39, 1−176 (1951).
29. Beebe, W. Zoologica 6, 149−241 (1934).
30. Lockett, G. H. & Millidge, A. F. British Spiders Vol. 1 (Royal Society, London, 1951).
31. Lockett, G. H. & Millindge, A. F. British Spiders (Royal Society, London, 1953).
32. Shinkai, E. & Takano, S. Spiders of Japan (Tokai University Press, 1984).
33. Koh, J. K. H. A Guide to Common Singapore Spiders (Singapore Science Centre, 1989).
34. Mascord, R. Australian Spiders (Reed, Wellington, New Zealand, 1970).



© 1992 Nature Publishing Group
Privacy Policy