Sequential Polygyny During Egg Attendance is Rare in a Tree Frog and Does not Increase Male Fitness Wei-Chun Cheng*, Yi-Huey Chen†, Hon-Tsen Yu‡, J. Dale Roberts§,¶ & Yeong-Choy Kam* * Department of Life Science, Tunghai University, Taichung, Taiwan † Department of Life Science, Chinese Culture University, Taipei, Taiwan ‡ Institute of Zoology and Department of Life Science, National Taiwan University, Taipei, Taiwan § Centre for Evolutionary Biology, School of Animal Biology M092, University of Western Australia, Crawley, WA, Australia ¶ Centre of Excellence in Natural Resource Management, University of Western Australia, Crawley, WA, Australia Correspondence Yeong-Choy Kam, Department of Life Science, Tunghai University, Taichung, Taiwan 40704, R.O.C. E-mail: biyckam@thu.edu.tw Hon-Tsen Yu, Institute of Zoology and Department of Life Science, National Taiwan University, Taipei, Taiwan 10617, R.O.C. E-mail: ayu@ntu.edu.tw Received: October 1, 2012 Initial acceptance: November 23, 2012 Final acceptance: January 11, 2013 (T. Tregenza) doi: 10.1111/eth.12062 Abstract Sequential polygyny is a reproductive strategy that allows males to con- tinue to mate and compensates for the loss of future breeding opportuni- ties incurred by parental care (i.e. egg attendance). Using the frog Kurixalus eiffengeri, we tested predictions that (1) attending males fathered two, overlapping clutches; and (2) that double clutching leads to improved offspring numbers. Using five microsatellite DNA markers, we genotyped 15 pairs of overlapping clutches, which differed slightly in developmental stage at a single egg-laying site. Parentage analyses showed at least 12 of 15 pairs of overlapping egg clutches were sired by the attend- ing male mated with different females, providing the first genetic evidence to support an earlier prediction that attending males sired both egg clutches. Field surveys found a low incidence of overlapping clutches (4.9% of 263 egg-occupied stumps), suggesting sequential polygyny is uncommon. Stumps with multiple clutches contained significantly more eggs than stumps with single clutches but hatched similar number of tad- poles. Results suggest that continuous calling that attracts females during egg attendance is a reproductive tactic that maximizes mating opportuni- ties. However, adoption of the sequential polygyny tactic may only result in marginal fitness gains for males that are traded off against average higher egg mortality in larger egg clutches. Parental investment is any parental effort put into an individual offspring that increases the offspring’s survivorship and hence the parent’s reproductive success. However, parental investment is at the cost of the parent’s ability to invest in other offspring and consequently future reproductive success (Wil- liams 1966; Trivers 1972; Sargent & Gross 1986). Time and the energy expended in gamete produc- tion and parental care are two major components of parental investment. As most male animals devote less time and energy to gamete production than females, reproductive success for males is usually determined by the number of successful matings rather than gamete production (Trivers 1972; Krebs & Davies 1993; Shuster & Wade 2003). Males can benefit more than females from increas- ing the number of mates, and therefore, male parental care is not expected if the time or energy allocated to current offspring results in a decrease in future mating opportunities (Sargent & Gross 1986; Krebs & Davies 1993; Manica & Johnstone 2004; Alonzo 2012). The reproductive strategies adopted by males are therefore shaped by the costs and benefit of parental care, that is, the trade-off between current and future reproductive outputs (Trivers 1972; Clutton-Brock 1991). Paternal egg attendance, a male parent remaining with an egg mass at a fixed location, is a common form of parental care in oviparous animals (Crump 1995; Smith & Wootton 1995; Manica & Johnstone Ethology 119 (2013) 286–295 © 2013 Blackwell Verlag GmbH 286 Ethology