The abundant-centre hypothesis using porcelain crabs
What is it about?
The abundant-centre hypothesis (ACH) is based on the assumption that physiological constraints limit populations at the edges of their distributional range. Here we examine the applicability of the ACH in a marine system by testing whether physiological predictions are reflected in large-scale variations of life-history traits of five porcelain crab species collected along the Chilean coast. The relative abundance and life-history traits showed different spatial patterns among species. Sex ratio showed a prominent hump-shaped pattern, with females prevailing in the centre of the ranges and males dominating towards the range boundaries; this pattern was statistically significant in three of the five studied species. The proportion of ovigerous females showed no clear latitudinal trends, and mature individuals were observed across most of the geographical range of the species. However, recruits tended to be absent towards the southern (poleward) boundaries of the distribution. We assumed that the ACH does not apply to all species equally.