Data from: Biodiversity patterns diverge along geographic temperature gradients

Models applying space-for-time substitution, including those projecting
ecological responses to climate change, generally assume an elevational
and latitudinal equivalence that is rarely tested. However, a mismatch may
lead to different capacities for providing climatic refuge to dispersing
species. We compiled community data on zooplankton, ectothermic animals
that form the consumer basis of most aquatic food webs, from over 1,200
mountain lakes and ponds across western North America to assess
biodiversity along geographic temperature gradients spanning nearly 3,750
metres of elevation and 30 degrees latitude. Species richness,
phylogenetic relationships, and functional diversity all showed
contrasting responses across gradients, with richness metrics plateauing
at low elevations but exhibiting intermediate latitudinal maxima. The
nonmonotonic/hump-shaped diversity trends with latitude emerged from
geographic interactions, including weaker latitudinal relationships at
higher elevations (i.e. in alpine lakes) linked to different underlying
drivers. Here, divergent patterns of phylogenetic and functional trait
dispersion indicate shifting roles of environmental filters and limiting
similarity in the assembly of communities with increasing elevation and
latitude. We further tested whether gradients showed common responses to
warmer temperatures and found that mean annual (but not seasonal)
temperatures predicted elevational richness patterns but failed to capture
consistent trends with latitude, meaning that predictions of how climate
change will influence diversity also differ between gradients. Contrasting
responses to elevation- and latitude-driven warming suggest different
limits on climatic refugia and likely greater barriers to northward range
expansion.