Data from: On the use of climate covariates in aquatic species distribution models: are we at risk of throwing the baby out?

Species distribution models (SDMs) in river ecosystems can incorporate
climate information by using air temperature and precipitation as
surrogate measures of instream conditions or by using independent models
of water temperature and hydrology to link climate to instream habitat.
The latter approach is preferable but constrained by the logistical burden
of developing water temperature and hydrology models. We therefore
assessed whether regional scale, freshwater SDM predictions are
fundamentally different when climate data versus instream temperature and
hydrology are used as covariates. Maximum Entropy (MaxEnt) SDMs were built
for 15 freshwater fishes using one of two covariate sets: (1) air
temperature and precipitation (climate variables) in combination with
physical habitat variables; or (2) water temperature, hydrology (instream
variables) and physical habitat. Three procedures were then used to
compare results from climate vs. instream models. First, equivalence tests
assessed average pairwise differences (site-specific comparisons
throughout each species’ range) among climate and instream models. Second,
‘congruence’ tests determined how often the same stream segments were
assigned high habitat suitability by climate and instream models. Third,
Schoener’s D and Warren’s I niche overlap statistics quantified range-wide
similarity in predicted habitat suitability values from climate vs.
instream models. Equivalence tests revealed small, pairwise differences in
habitat suitability between climate and instream models (mean pairwise
differences in MaxEnt raw scores for all species < 3×10-4).
Congruence tests showed a strong tendency for climate and instream models
to predict high habitat suitability at the same stream segments (median
congruence = 68%). D and I statistics reflected a high margin of overlap
among climate and instream models (median D = 0.78, median I = 0.96).
Overall, we found little support for the hypothesis that SDM predictions
are fundamentally different when climate versus instream covariates are
used to model fish species’ distributions at the scale of the Columbia
Basin.