Population and reproductive structure in the endangered and highly endemic freshwater crab Aegla concepcionensis (Decapoda:Pleocyemata:Aeglidae) from Chile

Abstract

Population and reproductive information of highly endemic species allow us to understand their underlying conservation problems. Aegla concepcionensis is restricted to a small and intervened Chilean basin, and its conservation status has varied from extinct in nature to endangered. We characterized their life history measuring population, morphological and environmental variables during an annual cycle capturing individuals with a catch and release method based on electroshocking. Although the maximum water temperature was related to the recruitment, it can be physiologically risky for the remaining macroinvertebrate community. The relationship between abundance and narrow pH variations indicates a condition of unstable equilibrium given the environmental deterioration by deforestation. Sex ratio was predominantly male biased during copulatory activity, and sexually dimorphic body size distributions supported the hypothesis of greater natural selection in females and sexual selection in males. The period of ovigerous females was comparatively restricted, late and consistent with an efficient ecophysiological strategy of reproductive investment. Patterns of pubertal moult, onset of morphometric maturity, absence of morphological differentiation in both sexes suggested that A. concepcionensis tends to maximize reproductive performance favouring the recovery of their relict populations.

Evolvability in the Cephalothoracic Structural Complexity of Aegla araucaniensis (Crustacea: Decapoda) Determined by a Developmental System with Low Covariational Constraint

“…Both functions optimize the quantity and quality of the new progeny, favoring population fitness by natural selection [ 15 , 16 ]. The greater anterior amplitude and prominence of the latero-frontal spines in males determine the performance of agonistic confrontations between males and copulatory behavior [ 17 , 18 , 19 ] These responses favor the individual fitness of males through mating success, which involves an important component of sexual selection [ 16 , 20 , 21 ]. We hypothesize that these divergent adaptive causes also influence the sexually dimorphic expression of functional modularity, because the direct developmental pathway is a weak driver of cephalothoracic canalization, which implies a low correlation in the asymmetry of the developmental modules and significant changes in the covariation structure that defines its modularity.…”