Less favourable climates constrain demographic strategies in plants

Correlative species distribution models are based on the observed relationship between species’occurrence and macroclimate or other environmental variables. In climates predicted less favour-able populations are expected to decline, and in favourable climates they are expected to persist.However, little comparative empirical support exists for a relationship between predicted climatesuitability and population performance. We found that the performance of 93 populations of 34plant species worldwide–as measured byin situpopulation growth rate, its temporal variation andextinction risk–was not correlated with climate suitability. However, correlations of demographicprocesses underpinning population performance with climate suitability indicated both resistanceand vulnerability pathways of population responses to climate: in less suitable climates, plants expe-rienced greater retrogression (resistance pathway) and greater variability in some demographic rates(vulnerability pathway). While a range of demographic strategies occur within species’ climaticniches, demographic strategies are more constrained in climates predicted to be less suitable.