Quantifying habitable water temperatures and thermal sensitivities among
species functional traits of stream invertebrates
Abstract
Ectothermic species have body temperatures that reflect their
environment to varying degrees. Environmental temperature drives all
cellular and physiological functions, including metabolism, development,
growth, migration, and reproduction. Extreme temperatures are occurring
more frequently with climate change, and understanding the thermal
tolerance and adaptive traits of species is critical.We hypothesized
that 1) geographic location of stream ecosystems, such as elevation and
latitude, influence the habitable water temperature of lotic (stream)
invertebrates because the thermal habitat of species directly influences
their life cycle and consequently fitness and 2) species functional
traits (e.g., voltinism and feeding behavior) are influenced by
habitable temperature. Here, we tested these hypotheses across diverse
taxa and geographic regions using a dataset for stream invertebrates
traits across North America. We showed that maximum water temperature in
habitats and thermal breadth were significantly lower and narrower
across streams ranging in elevation, from 0 to 3000 m, suggesting that
invertebrate taxa across various elevations are less tolerant of warmer
water temperature. Also, we identified thermal sensitivity differences
among species traits, especially functional feeding group traits, as
these are related to habitat selection in stream ecosystems. Our
synthesis suggests that elevation and species traits can help predict
thermal breadth and thermal tolerance for different species under a
changing climate.