Is species richness congruent among taxa? Surrogacy, complementarity, and environmental correlates among three disparate taxa in geographically isolated wetlands

Globally, there is a growing awareness that geographically isolated wetlands contribute to important landscape functions and ecological services. One of their most important functions is providing habitat to a diverse fauna and flora adapted to variable wet and dry environments. We focus on analysis of similarities among three distinct taxa, vascular plants, aquatic beetles, and amphibians, in isolated wetlands in the southeastern coastal plain of Georgia. Although species richness for these three taxa is quite high in isolated wetlands at a regional scale, we found a low degree of congruence in species richness and species composition among taxa. This finding demonstrates that none of these groups could be used as a surrogate for the overall biodiversity of these wetlands represented by the three taxa. We identified environmental factors influencing the complex patterns of species richness and distribution for the three groups that indicate biotic and abiotic processes operate at different scales for each taxonomic group and for individual species. Our study illustrates the importance of considering structural diversity, hydrologic variation, and landscape position as key elements to understanding overall diversity represented by the three taxa in isolated wetlands and in developing assessment tools of wetland condition.

▸ Plants, amphibians and coleopterans had low congruence among taxa in isolated wetlands. ▸ No taxa could be used as a surrogate to predict species richness or presence of other taxa. ▸ Environmental factors influencing species distribution patterns differed among taxa.