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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.09.019 Byline: Leeann T. Reaney Abstract: While mate choice is often assumed to be based on an absolute value that may reflect underlying male quality, many mating systems facilitate the comparative evaluation of males. Females can encounter a number of potential mates, either sequentially or simultaneously, before making a mate choice decision. Consequently, the attractiveness of one male may depend on the attractiveness of other males a female has previously encountered. To examine whether female choice in the fiddler crab Uca mjoebergi is based on the comparative evaluation of males, I altered the social context in which a set of males were encountered. Using a robotic crab system to manipulate claw size and wave rate directly, I determined female preference for two male options in the absence and presence of an asymmetrically dominating decoy option. The decoy male option was designed to change the relative attractiveness of the initial two male options. The presence of the decoy significantly altered the absolute preference, but not the relative preference, for the two male options. While this study clearly demonstrates that female U. mjoebergi are not using strict absolute preferences when ranking each male's attractiveness, it does not conclusively support comparative evaluation mechanisms. One possibility is that sexually selected traits in a complex signalling system often vary in how reliably they reflect male quality, and females may use a combination of absolute and comparative measures when assessing male quality. Author Affiliation: School of Botany and Zoology, The Australian National University Article History: Received 30 April 2008; Revised 11 July 2008; Accepted 20 September 2008 Article Note: (miscellaneous) MS. number: 08-00275R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2007.09.021 Byline: Leeann T. Reaney, Richard N.C. Milner, Tanya Detto, Patricia R.Y. Backwell Abstract: Underlying male quality is often reflected in the condition of sexually selected traits. In fiddler crabs, male success in both intra- and interspecific interactions is highly dependent on the size of the major claw. However, males are often forced to autotomize their major claw. Claw regeneration significantly altered the structure of a males' major claw in Uca mjoebergi. We found, however, that claw regeneration did not affect signal quality. Both males and females were unable to visually distinguish a regenerated claw from an original claw. Although regenerated males were inferior fighters, males were able to compensate for this fighting disadvantage by avoiding fights with other males. Regenerated males were, however, less likely to acquire and defend high-quality territories and consequently suffered a decrease in mating success. Author Affiliation: School of Botany and Zoology, The Australian National University, Canberra, Australia Article History: Received 9 July 2007; Revised 15 August 2007; Accepted 23 September 2007 Article Note: (miscellaneous) MS. number: 9450

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.05.022 Byline: Leeann T. Reaney Abstract: Although many animals use refuges to avoid predators, it is often costly to do so. The longer an individual remains in a refuge, the less time it has available for other essential activities, such as foraging and mate searching. Animals should therefore optimize the time spent in a refuge after an attack by adopting a flexible approach to predator avoidance. I examined refuge use in the fiddler crab, Uca mjoebergi, under variable foraging and mating contexts on a mudflat in Australia. There were no sex or size differences in refuge use, suggesting that there are no morphological or gender biases in predation risk. Risk-taking behaviour in U. mjoebergi was, however, highly flexible and appeared to be strongly dependent on the trade-off between the costs and benefits of hiding. Refuge use varied between optimal foraging and reproductive periods of a semilunar cycle. Loss of foraging time influenced risk-taking behaviour in both males and females since both were quicker to re-emerge when food levels were high. During the reproductive period, crabs took longer to re-emerge because of few foraging opportunities, as well as few mating opportunities since receptive females were rare. However, when mating opportunities for males were experimentally increased by introducing a tethered female, actively courting males engaged in highly risky behaviour and re-emerged after a few seconds, with some males abandoning refuge use completely. Refuge use in U. mjoebergi is therefore highly flexible, with the decision to re-emerge influenced by fitness benefits. Author Affiliation: School of Botany and Zoology, The Australian National University, Australia Article History: Received 23 February 2006; Revised 5 April 2006; Accepted 23 May 2006 Article Note: (miscellaneous) MS. number: 8855R