Biogeographical patterns of freshwater fauna

Aim Temperature is regarded as an important driver of broad-scale
biodiversity patterns. However, less is known of the role of dispersal in
shaping broad-scale species and trait distributions, particularly given
that species had to disperse out of glacial refugia after the Last Glacial
Maximum (LGM). Here, we used a unique dataset describing the distributions
of freshwater fauna combined with trait information, to evaluate
biodiversity relationships to distance to glacial refugia and temperature.
Location 25 biogeographical regions across Europe Time period Data from
species occurrence gathered in 1978 Major taxa studied 2,816 freshwater
invertebrate species and 230 freshwater fish species Methods using the
occurrence of invertebrate and fish species on the biogeographical
regions, and publicly available trait information, we analyzed patterns in
diversity indices (i.e., species richness, trait richness, and trait
redundancy), trait distribution, and species and trait β-diversity, and
their relationship to distance to known glacial refugia and regional
temperature. Results We show that distributions of European invertebrate
and fish species and traits are primarily explained by distance to refugia
and its covarying effect with temperature (i.e., refugia tend to be
warmer). Specifically, species and trait richness were higher in regions
proximate to refugia and lower in distant regions. Additionally,
communities in colder and distant regions exhibited reduced niche
dimensions and slower life histories, suggesting increased vulnerability
to environmental change. Main conclusions Species more distant from their
refugia were characterized by higher dispersal capacities. Accordingly,
since the LGM, only a subset of species was able to colonize distant
regions, while many species have spatial ranges constrained by their
dispersal capacity, increasing their potential for extinction under
ongoing climate change. Therefore, additional conservation measures
considering species’ dispersal capacities are required.