| Mate choice and sex ratio allocation in the side blotched lizard
photo credit: Barry Sinervo |
I have been collaborating with Barry Sinervo at the University of California Santa Cruz to examine the impact of interactions within and between the sexes on the reproductive strategies of the side-blotched lizard, Uta stansburiana. The side-blotched lizard exhibits genetically based throat colors (orange, blue, or yellow) that could be used as a sexually selected signal since they reliably predict the genetic quality of mates. The frequency of male and female morphs cycle between years, and both male and female morphs have an advantage when rare, thus genetic quality will depend on morph frequency. We examined a game theoretical model that predicts female mate choice as a function of morph frequency and population density (Alonzo and Sinervo 2001). The model predicts the following flexible mate choice rule: both female morphs should prefer rare males in ‘boom years’ of the female cycle (e.g., ‘rarest-of-N rule’), but prefer orange males in ‘crash years’ of the female cycle (‘orange-male rule’). In the side-blotched lizard, cycling mate choice games and context-dependent mate choice are predicted to maintain genetic variation in the presence of choice for good genes. Experiments testing these predictions are currently underway.
We also studied patterns of sex ratio allocation in this species (Alonzo and Sinervo Submitted). In this species, the expected fitness of sons and daughters depends on population density, social environment, and individual genotype. Using a game theoretical model, we predict that female sex ratio bias will be context-dependent conditional on female morph, population density, social environment, and mate quality. The predicted patterns of sex ratio bias have been observed experimentally and suggest that sex allocation theory is most powerful when known fitness effects through sexual and natural selection are considered concurrently.
For more information on the side-blotched lizard see Barry Sinervo’s website.
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