Animal Biology




Nicola Watson


Start date

Mar 2007

Submission date

Mar 2010

Nicola Watson

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The Evolution of Female Ornamentation in Onthophagine Dung Beetles


My thesis is an investigation into the evolution of female ornamentation, using the dung beetle, Onthophagus sagittarius, as a model species.

My research will determine the sex roles of the species and identify potential intra and inter-sexual selection pressures that may have led to the evolution of female horns in O.sagittarius.

I am interested in how the level of horn expression is correlated with individual fitness, the role of female horns in female-female competition and male mate choice, and the genetic basis of horn expression.

Why my research is important

The evolutionary importance of secondary sexual traits in enhancing reproductive success among males has long been recognised, and empirical support for the function of male armaments and ornaments in inter and intrasexual competition is vast. However, there are a number of species in which females also exhibit secondary sexual characteristics, and this phenomenon still remains poorly understood.

Horns are characteristic of male dung beetles and serve as weapons during male-male competition.

In the dung beetle Onthophagus sagittarius, females exhibit horns that are qualitatively different from and much larger than those present in males. The reasons for this are not understood.

A better understanding of the potential selective pressures operating to favour the evolution of armaments and ornaments in females is required and necessary to re-address the imbalance of sexual selection studies that focus solely on sexual selection on males.


  • International Postgraduate Research Scholarship