The influence of climate and palaeoclimate on distributions of global conifer clades depends on geographical range size

Aim We investigate how plant distributions are shaped by current and palaeoclimate regimes. We specifically use global conifer biodiversity to test if palaeoclimatic signatures are stronger in range‐restricted taxa relative to widespread taxa. Location Global. Taxon Coniferales. Methods We combine global geographical occurrences for 606 conifer species and 69 conifer genera with climate information (modern day and palaeoclimate) to examine the predictors of current conifer distribution. We test how climate predicts the richness of range‐restricted taxa and influences turnover of widespread taxa using generalized dissimilarity models and a zeta diversity framework. We also construct ensemble distribution models to test if palaeoclimates differentially influence the current distribution of range‐restricted versus widespread taxa. Results Generalized dissimilarity models suggest that palaeoclimatic variation is associated with richness differences among small‐range species and genera; specifically, most occur in areas with little temporal climatic variation. Turnover among more widespread taxa, in contrast, is more strongly related to broad modern and palaeoclimatic temperature gradients. Ensemble distribution models also suggest that palaeoclimatic variation contributes more to the current range of genera with restricted ranges. Main conclusions The most widespread conifers broadly follow past and current temperature gradients, leading to latitudinal sorting of genera based on their physiological adaptations. Range‐restricted species and genera, however, preferentially occur in climatically stable regions where they contribute to richness hotspots. History, rather than current climate patterns, likely exerts a disproportionate influence on global richness patterns in the group.