Life-History Evolution in Guppies (Poecilia reticulata: Poeciliidae). IV. Parallelism in Life-History Phenotypes

Abstract

In earlier publications, we reported an association between the life-history patterns of guppies and the types of predators with which they co-occur. We contrasted guppies from high-predation sites (Crenicichla localities) with those from low-predation sites (Rivulus localities) found on the south slope of the Northern Range Mountains of Trinidad. Guppies from high-predation localities attain maturity at an earlier age and smaller size, produce more and smaller offspring per litter, and have higher reproductive allotments than their counterparts from low-predation sites. Here we present a parallel series of analyses for guppies from a new series of localities on the north slope of the Northern Range. These fish are also found in what appear to be high- and low-predation communities, but, with one exception, the species of predators are entirely different from those on the south slope. The larger predators are derived from marine families (gobies and mullets) that have invaded freshwater rivers; the south slope fauna is derived from families typical of mainland South America. If predator-induced mortality selects for life-history evolution, then guppies from high- and low-predation sites on the north slope should have life histories similar to their counterparts on the south slope. We compare the life-history phenotypes of guppies from the north slope communities and find that the high- and low-predation contrasts are remarkably similar to those reported earlier for the south slope communities. We reinforce this comparison with multivariate analyses that use discriminant functions derived for the south slope collections to classify north slope samples. Finally, we exploit recent molecular genetic data and the geographical distribution of high- and low-predation communities to argue for the independent origin of these life-history patterns in each drainage.