Niche overlap and ecological tolerance of non-marine Ostracoda in Turkey

Abstract

AbstractWe applied niche overlap indices to for the first time show possible correlational occurrences among 40 non-marine ostracod taxa from seven aquatic habitats (lakes, creeks, ponds, springs, ditches, pools, troughs) in Turkey. Ecological tolerance and optimum estimates of each species were calculated and compared to explain possible reasons for habitat utilization. Eleven species were found suitable for the application of these indices. Overlap ranges of five of the species were found suitable for five variables (pH, dissolved oxygen, water temperature, electrical conductivity, and elevation; P < 0.05). Heterocypris incongruens (Ramdohr, 1808) and H. salina (Brady, 1868) were the only two species with common overlap for all the five variables. These two species generally showed common resource-utilization curves for each of these variables along with relatively similar tolerance ranges. Complete overlap was only possible for some cosmoecious species when they displayed wide-tolerance ranges and low optimum estimates for different environmental variables. Results suggest that cosmopolitan species do not only have wide geographical distributions but tolerance ranges higher than other species. Such wide tolerance ranges seem to help species coinhabit with each other and elevate their co-occurrence probabilities in different types of habitats. Applying the first usage of overlap indices on ostracods and attempting to show the relationship between niche overlap and species ecological tolerance could nevertheless provide a new tool to apply in future studies.