Measuring ecological specialization along a natural stress gradient using a set of complementary niche breadth indices

cological specialization refers to a restricted ecological niche breadth fora species, resulting from the trade-off between range of the resources it canexploit and efficacy in exploiting a specific resource. One hypothesis predictsthat specialist species should be dominant in stressful environments, whereasgeneralist species should be dominant at less extreme environmental gradients.An alternative hypothesis states that specialization should be favoured in stablesystems, and that ecological disturbances should affect specialist species nega-tively. These hypotheses have been poorly tested. Mediterranean coastal dunesystems are characterized by strong sea–inland environmental gradients, idealfor tackling this challenge. We ask: (1) is distribution of specialist and generalistplant species related to this gradient; and (2) do different specialization indicesindicate congruent or complementary pattern