Neighbor effects on population growth rate differ among populations due to variation in demographic rate sensitivities in Sedum lanceolatum

Population growth rates will respond to an environmental driver only if
the driver impacts demographic rate(s) and the population is sensitive to
impacted demographic rate(s). If populations vary in the sensitivity of
population growth rate to demographic rates, the effect of an
environmental driver on population growth rate could vary across
populations, even if the effect of the driver on demographic rates does
not vary across populations. Here, we use five years of demographic data
of a common alpine plant, including data from a neighbor removal
experiment and a climate warming experiment, to quantify the relative
contribution of neighbor effects on demographic rates vs. sensitivity of
population growth rate to demographic rates to across-population variation
in neighbor effects on population growth rate. We find neighbor effects on
population growth rate vary significantly across populations, and this
effect is driven primarily by variation in sensitivity of population
growth rate to demographic rates across populations. Further, results from
our climate warming experiment suggests variation in sensitivity across
populations is partly driven by temperature differences. Our results
highlight the importance of considering changes in the sensitivity of
population growth rate to demographic rates across space, and show how
changes in sensitivity can contribute to spatial variation in the effects
of a driver on population growth rate.