Ecogeographic patterns of macrophyte metacommunities in the Hengduan Mountain region

Biological communities exhibit multiple distribution patterns at the metacommunity scale, and assessing the major drivers of these patterns is a key issue in community ecology. Here we investigated how the environmental and geographic gradients shape the distribution patterns of macrophytes at the metacommunity level. We applied the framework of the elements of the metacommunity structure (EMS) to identify the distinct types of 48 macrophyte metacommunities in the Hengduan Mountain region (HDMR) of China. We then used a generalized linear model and model selection approaches to determine which variables contributed to the variations of EMS and linear discriminant function analysis to evaluate how well the tested variables predicted metacommunity patterns. We found wide variations in the 3 EMS (i.e., coherence, range turnover, and range boundary clumping): latitude and alpha diversity were most important in determining coherence; nestedness was mostly related to turnover; and sampling depth was significantly associated with boundary clumping. Seven metacommunity types were identified in HDMR, and most metacommunities best fitted the Gleasonian and Clementsian patterns as well as their quasi-structures. Notably, Gleasonian and Q-Gleasonian patterns as well as the other 3 patterns (i.e., Q-nested, evenly spaced, and nested) were for the first time detected for macrophytes. These metacommunity types were best discriminated by nestedness, altitude, and latitude. Our results provide strong evidence of the impact of geographic patterns on macrophyte metacommunities, with the Gleasonian patterns dominant at both ends of the latitude/altitude gradient and Clementsian patterns common near the central part of the gradient.