Does quality affect growth rate and age at maturity in species with indeterminate growth?

Background: Life-history theory uses optimality models to predict variation in age and size at first reproduction. Whether these models prove successful at the among-population level, they often fail at the within-population level because they do not take into account the frequency-dependent effects of optimal life-history strategies. Questions: Are quality-dependent differential costs of growth rate responsible for within-population variation in life-history traits? Mathematical Methods: Two-player non-zero-sum game. Key assumptions: Males of either high or low quality can choose to grow fast or slow and to reach maturity early or late. Growth is biphasic and decreases after sexual maturity. Growth rate imposes differential survival costs to high and low quality males. Independent of their quality, large males experience a higher mating success. Predictions: if there is variation in size and age at first reproduction then (i) high-quality males are expected to grow faster than low-quality males and (ii) fast-growing males are expected to mature earlier than slow-growing males. Study organisms: male Tyrrhenian treefrogs, Hyla sarda (Anura: Hylidae) Methods: we measured the age and the body size of two groups of reproductive males: males that were first captured at the breeding site in 2007 and recaptured in 2008 (recaptured males) and males that were captured in 2008 for the first time (newly-captured males). Results: Recaptured males were larger than newly-captured males of both their 2008 and 2007 age classes. Conclusions: Both the theoretical and the empirical models suggest that differential costs in growth rate may play an important role in explaining within-population variation in age and size at first reproduction.