Dryland reservoirs support greater taxonomic and functional beta diversity of zooplankton regardless of hydrological period.

More heterogeneous environments allow for greater availability of ecological niches, thus favoring greater species diversity. However, it is not yet established how heterogeneity influences taxonomic and functional beta diversity. Therefore, we aimed to determine how environmental heterogeneity affects the patterns of taxonomic and functional beta diversity of planktonic microcrustaceans in reservoirs in different regions (semiarid and humid) in Northeast Brazil, in addition to verifying the influence of dry and rainy periods on these measures. Sampling from the semiarid region was carried out between 2013 and 2016, while samples from the humid region were collected between 2019 and 2021. Environmental heterogeneity and taxonomic and functional beta diversity were greater in the semiarid region, regardless of the hydrological period. However, regardless of the region, taxonomic beta diversity was greater during the dry period, while functional beta diversity did not differ between periods. Both types of diversity were driven mainly by local factors in the semiarid region, considered a region of high environmental heterogeneity due to the geomorphological and climatic characteristics that differentiate it from other regions. This type of study reinforces the need to conserve these reservoirs, especially those located in the semiarid region, as they support greater variability in species composition and functional traits. [ABSTRACT FROM AUTHOR]