Life-History Variation in Caribbean gambusia, Gambusia puncticulata puncticulata (Poeciliidae) from the Cayman Islands, British West Indies

We studied seasonal and spatial variability in the reproductive life-history traits of Caribbean gambusia, Gambusia puncticulata puncticulata, using collections representing dry and wet periods from eight pond sites located across the three Cayman Islands. Caribbean gambusia exhibited a seasonal life-history response over the 5-month interval between the relatively dry and wet periods, marked by shifts to larger adult sizes and smaller broods made up of larger offspring. This seasonal shift in the life-history pattern coincided with increased rainfall, lower salinity, lower water temperature, and higher food availability. Overall, there was a reproductive trade-off involving a reciprocal relationship between brood size and mean embryo mass, and a direct relationship between brood size and total embryo mass. Levels of various environmental variables, including salinity, submerged aquatic vegetation cover, and capture depth, were apparently unrelated to the life-history pattern. Furthermore, the life-history pattern did not reflect an island effect. However, a correlation between the seasonal difference in salinity and offspring size suggested that the Cayman Island life-history pattern may correspond in part with the environmental stability hypothesis.