Zooplankton body size is filtered by a thermo‐oxygenic niche at the regional scale

Abstract

AbstractAimThere is ongoing debate regarding the extent to which body size is selected by the environment. To address this issue, we assessed how thermo‐oxygenic conditions select body size of rotifer species composing a regional species pool.LocationApproximately 600 different water bodies in Sweden.TaxonRotifers (188 species).MethodsData were acquired from previously published studies. For the environmental parameters, we conducted principal component analysis (PCA) to recognize the pattern among the species‐specific thermal and oxygenic preferences of rotifers of different ecology. We assigned a standard body length to each species. We performed phylogenetically correlated analyses to evaluate the relationships between body length and the parameters that were selected as PCA drivers.ResultsThermal and oxygenic tolerance ranges, designated by the differences between the minimum and maximum of species occurrence, were grouped separately from the optima designated by the conditions referring to the highest species abundance, according to PC1 versus PC2. The parameters representing temperature and oxygen occupied opposite positions on the PC2 axis. Body size selection was driven by both temperature and oxygen, but the cues for this selection differed; species with higher thermal optima were smaller, while species with wider oxygen tolerance ranges were larger.Main conclusionThe body sizes of rotifer species are filtered by both thermal and oxygenic conditions. Selection is driven by tolerance ranges and optima. Oxygenic conditions are as important as thermal conditions in body size selection within a species assemblage.