Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The scaling of average daily metabolic rate and energy intake
- 3 Why do larger species invest relatively less in their offspring?
- 4 The intraspecific relationship of parental investment to female body weight
- 5 Growth and productivity
- 6 Quantitative models of body size
- 7 Sexual dimorphism in body size
- 8 Are larger species more dimorphic in body size?
- 9 Surface area/volume arguments in biology
- 10 Prospectus
- Glossary of mathematical terms
- References
- Index
8 - Are larger species more dimorphic in body size?
Published online by Cambridge University Press: 02 December 2009
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 The scaling of average daily metabolic rate and energy intake
- 3 Why do larger species invest relatively less in their offspring?
- 4 The intraspecific relationship of parental investment to female body weight
- 5 Growth and productivity
- 6 Quantitative models of body size
- 7 Sexual dimorphism in body size
- 8 Are larger species more dimorphic in body size?
- 9 Surface area/volume arguments in biology
- 10 Prospectus
- Glossary of mathematical terms
- References
- Index
Summary
Many authors, from Darwin (1871) onwards, have considered factors that might affect the degree of sexual dimorphism. Two generalizations are frequently made. First, that dimorphism increases with the degree of polygyny (e.g. Crook, 1962; Lack, 1968; Clutton-Brock & Harvey, 1976; Clutton-Brock et al., 1977; Alexander et al., 1979) and, secondly, that larger species are more dimorphic (e.g. Rensch, 1950; Wiley, 1974; Rails, 1976a; Leutenegger, 1978; Harvey & Mace, 1982). Intrasexual selection acting on males is usually given as the reason why males are larger than females in polygynous species (Selander, 1972; Belovsky, 1978). With increased polygyny increased sexual selection is expected, with the predicted consequence that the sexes should differ more in their optimal sizes. More recently, however, the role of selection for optimal female size has been emphasized, and advantages for smaller females have been postulated in polygynous species (Willner & Martin, 1985; Robinson, 1986).
The reasons, however, why larger species should exhibit greater sexual dimorphism in body size are less apparent than the reasons why more polygynous species should be more dimorphic. This chapter first reviews the evidence for the association between size and sexual dimorphism, and then considers those theories that predict that larger species should show greater dimorphism in body size.
A review of the evidence
Rensch (1950) and Rensch (1959) are frequently cited as evidence that sexual dimorphism is greater in larger species, but the data are unconvincing. No data are presented in Rensch (1959). In his 1950 paper, Rensch presented information from birds, mammals and carabid beetles.
- Type
- Chapter
- Information
- The Allometry of Growth and Reproduction , pp. 117 - 128Publisher: Cambridge University PressPrint publication year: 1989