Connection and isolation degree of the environment as force in the shape patterns in the freshwater prawns Palaemonetes argentinus

ITUARTE, R. B.; GIRI F.; COLLINS P.; VAZQUEZ M.G.; TORRES, M. V; RUMBOLD, C.

Barcelona

Congreso; The Crustacean Society Mid-Year Meeting, 2017; 2017

The Crustacean Society - Universitat de BArcelona

Population connectivity can be thought as the degree to which populations in all their geographic distribution range are linked through the exchange and establishment of the individuals. When populations are separated by long distances or geographic barriers, they often present restricted gene flow, which can allow a phenotypic divergence among populations. Cephalothorax shape variations of freshwater prawn Palaemonetes argentinus between isolated and connected environments were evaluated. Geometric tools were used to compare the prawn shapes from environments with different degree of connection at Pampean lagoons. Configurations of 15 landmarks were digitised to represent the lateral cephalothorax structure. Allometry and sexual dimorphism were tested. Canonical Variate Analyses (CVA) was applied to compare the shape between prawns of lagoons in each sex. The correlations and covariations among shapes and geographical location were analyzed with Partial Least-Squares analysis. The CVA showed that the prawns of isolated lagoons were significantly different in shape, while prawns of connected lagoons were similar showing a greater overlap. Correlations and covariations among shapes and geographical location were high and significant. These results suggest that populations that were more distant and geographically isolated (different sub-basins) had different morphological conditions from those of populations of nearby and connected sites. This variation can be the product of the level of interchange of individuals between populations more or less distant, with barriers or facilitators of movement. Low geographical differentiation of cephalothorax shape is attributable to the gene flux and consequent homogenisation that results from the continuous distribution of this species and its free dispersal.