Shared and unique features of morphological differentiation between predator regimes inGambusia caymanensis

Abstract

When multiple groups of organisms experience similar environmental gradients, their patterns of differentiation might exhibit both shared and unique features. Here, we investigated the relative importance of three factors in generating body shape variation in a livebearing fish, Gambusia caymanensis, inhabiting the Cayman Islands: (i) shared patterns of divergent selection between predator regimes (presence/absence of piscivorous fish) driving replicated morphological differentiation, (ii) historical island effects yielding different morphologies across the three islands and (iii) unique effects of predation on morphological differentiation within each island. Shared effects of predation proved much more important than historical or unique effects. Populations coexisting with piscivorous fish exhibited larger caudal regions and smaller heads than conspecifics found in the absence of predatory fish. These results match a priori predictions, and mirror recent findings in a number of fish species, suggesting predation might often drive predictable morphological trends in disparate fishes. However, interestingly, the sexes achieved this morphological pattern through different means: head depth, caudal peduncle length and depth in males; head length, caudal peduncle depth in females. In G. caymanensis, we quantitatively confirmed that predation intensity represents a primary driver of body shape differentiation.

Shape variation in the least killifish: ecological associations of phenotypic variation and the effects of a common garden

“…2005; Hendry et al. 2006; Langerhans and Makowicz 2009). In these locations, the lentic ponds do, on average, present male H. formosa with a higher predation risk.…”

Shared and unique morphological responses of stream fishes to anthropogenic habitat alteration

“…On the other hand, the stream habitats in this basin may have environmental conditions that resemble reservoirs, leading to similar morphologies in the two habitats. More probably, however, the different evolutionary histories of populations in the different basins may influence their phenotypic responses to similar selective pressures among basins [41]. Indeed, the basin  habitat term was significant in three of the four species-based MANCOVAs (indicating unique responses of populations to reservoir habitats in the different basins; table 1).…”

Geographical and morphological variation within and between colour phases inCoris julis(L. 1758), a protogynous marine fish

“…Despite the fact that time series of sea temperature and chlorophyll a data are now easy to obtain as satellite-derived data, such data have not been widely used to study patterns of morphological variation in the field. Although patterns of geographical variation in body shape have been studied in both marine and freshwater species, the possible differences between sexes in such patterns have been explored, to the best of our knowledge, only in gonochorist freshwater species (Hendry et al, 2006;Langerhans & Makowicz, 2009). While various studies on the morphometric variation in hermaphrodite fish species exist (Vidalis, Markakis & Tsimenides, 1997;Moran, Burton & Caputi, 1999;Palma & Andrade, 2002, they do not use advanced techniques such as the combination of geometric morphometrics and spatial analysis and they do not test for differences between sexual phases in patterns of geographical variation.…”