Data from: Chloroplast population genetics reveals low levels of genetic variation and conformation to the central–marginal hypothesis in Taxus wallichiana var. mairei, an endangered conifer endemic to China

The central–marginal hypothesis predicts that geographically peripheral
populations should exhibit reduced genetic diversity and increased genetic
differentiation than central populations due to smaller effective
population size and stronger geographical isolation. We evaluated these
predictions in the endangered conifer Taxus wallichiana var. mairei. Eight
plastid simple sequence repeats (cpSSRs) were used to investigate plastid
genetic variation in 22 populations of Taxus wallichiana var. mairei,
encompassing nearly its entire distribution range. Low levels of plastid
genetic variation and differentiation were detected in the populations,
and the findings were attributed to low mutation rates, small population
sizes, habitat fragmentation and isolation, and effective pollen or seed
dispersal. Hunan and Hubei were identified as major refugia based on the
number of private haplotypes and species distribution modeling. Trends in
plastid genetic diversity and genetic differentiation from central to
peripheral populations supported the predictions of the central–marginal
hypothesis. In scenarios wherein the future climate becomes warmer, we
predict that some peripheral populations will disappear and southern and
southeastern regions will become significantly less habitable. Factors
that include the levels of precipitation during the driest month, annual
precipitation level, and annual temperature range will be decisive in
shaping the future distribution of these populations. This study provides
a theoretical basis for the conservation of T. wallichiana var. mairei.