Data from: Lifetime fitness, sex-specific life history, and the maintenance of a polyphenism

Polyphenisms, alternative morphs produced through plasticity, can reveal
the evolutionary and ecological processes that initiate and maintain
diversity within populations. We examined lifetime fitness consequences of
two morphs in a polyphenic population of Arizona Tiger Salamanders using a
27-year data set with 1,317 adults and 6,862 captures across eight
generations. Larval salamanders develop into either an aquatic paedomorph
that retains larval traits and stays in its natal pond or a terrestrial
metamorph that undergoes metamorphosis. To evaluate the adaptive
significance of this polyphenism, we compared lifetime reproductive
success of each morph and assessed how life history strategies and
spatiotemporal variation explained fitness. We found sex-specific
differences in lifetime fitness between morphs. For males, paedomorphs had
more reproductive opportunities than metamorphs when we accounted for the
potential mating advantage of larger males. For females, in contrast,
metamorphs had higher estimated egg production than paedomorphs. Life
history strategies differed between morphs largely because the morphs
maximize different ends of the trade-off between age at first reproduction
and longevity. Spatiotemporal variation affected larval more than adult
life history traits with little to no effect on lifetime fitness. Thus,
environmental variation likely explains differences in morph production
across time and space but contributes little to lifetime fitness
differences between morphs and sexes. Our long-term study and measures of
lifetime fitness provide unique insight into the complex selective regimes
potentially acting on each morph and sex. Our findings motivate future
work to examine how sex-specific selection may contribute to the
maintenance of polyphenism.