Journal of Biosciences

, Volume 35, Issue 2, pp 257–265

Unusual allometry for sexual size dimorphism in a cichlid where males are extremely larger than females


DOI: 10.1007/s12038-010-0030-6

Cite this article as:
Ota, K., Kohda, M. & Sato, T. J Biosci (2010) 35: 257. doi:10.1007/s12038-010-0030-6


When males are the larger sex, a positive allometric relationship between male and female sizes is often found across populations of a single species (i.e. Rensch’s rule). This pattern is typically explained by a sexual selection pressure on males. Here, we report that the allometric relationship was negative across populations of a shell-brooding cichlid fish Lamprologus callipterus, although males are extremely larger than females. Male L. callipterus collect and defend empty snail shells in each of which a female breeds. We found that, across six populations, male and female sizes are positively correlated with not only sexual and fecundity selection indices, but also with shell sizes. Given their different reproductive behaviours, these correlations mean that males are required to be more powerful, and thus larger, to transport larger shells, while female bodies are reduced to the shell size to enable them to enter the shells. Among the three size selections (sexual selection, fecundity selection and shell size), shell size explained the allometry, suggesting that females are more strongly subject to size selection associated with shell size availability than males. However, the allometry was violated when considering an additional population where size-selection regimes of males differed from that of other populations. Therefore, sexual size allometry will be violated by body size divergence induced by multiple selection regimes.


Phenotypic plasticitysexual selectionshell-broodingshell size

Abbreviations used




reduced major axis


standard length


sexual size dimorphism



Copyright information

© Indian Academy of Sciences 2010

Authors and Affiliations

  1. 1.Department of ZoologyKyoto UniversitySakyo, KyotoJapan
  2. 2.Department of Biology and GeosciencesOsaka City UniversitySumiyoshi, OsakaJapan
  3. 3.Faculty of Tourism and Environmental StudiesNagano UniversityUeda, NaganoJapan