Parallel adaptation prompted core-periphery divergence of Ammopiptanthus mongolicus

Abstract

Range expansion requires peripheral populations to shift adaptive optima to breach range boundaries. Opportunities for range expansion can be assessed by investigating the associations of core-periphery environmental and genetic differences. This study investigates differences in the core-periphery adaptation of Ammopiptanthus mongolicus, a broad-leaved evergreen shrub species in a relatively homogeneous temperate Asian desert environment, to explore the environmental factors that limit the expansion of desert plants. Temperate deserts are characterized by severe drought, a large diurnal temperature range, and seasonality. Long-standing adaptation to the harsh desert environment may confine the genetic diversity of A. mongolicus, despite its distribution over a wide range of longitude, latitude, and altitude. Since range edges defined by climate niches may have different genetic responses to environmental extremes, we compared genome-wide polymorphisms between nine environmental core populations and ten fragmented peripheral populations to determine the “adaptive peripheral” populations. At least four adaptive peripheral populations had similar genetic-environmental association patterns. High elevations, summer drought, and winter cold were the three main determinants of converging these four adaptive peripheral populations. Elevation mainly caused similar local climates among different geographic regions. Altitudinal adaptation resulting from integrated environmental-genetic responses was a breakthrough in breaching niche boundaries. These peripheral populations are also located in relatively humid and warmer environments. Relaxation of the drought and cold constraints facilitated the genetic divergence of these peripheral populations from the core population’s adaptive legacy. We conclude that pleiotropic selection synchronized adaptative divergence to cold and drought vs. warm and humid environments between the core and peripheral populations. Such parallel adaptation of peripheral populations relies on selection under a background of abundant new variants derived from the core population’s standing genetic variation, i.e., integration of genetic surfing and local adaptation.

Genomic insights into local adaptation and vulnerability of Quercus longinux to climate change

“…For example, the low spring precipitation and high clay content in habitats in southeastern Taiwan may act as strong environmental stresses that initiate genetic and phenotypic adaptation (e.g., drought resistance) in response to local conditions. In plant species, hostile environmental conditions in edge populations prompt local adaptation processes [103]. Distinct environmental pressure, along with a lack of migration between HC and the rest of the Q. longinux population, could speed up the fixation of alleles in a relatively smaller group, further facilitating the genetic and phenotypic adaptation [25,104].…”

Relict Plants Are Better Able to Adapt to Climate Change: Evidence from Desert Shrub Communities

“…It is speculated that island isolation may occur in the future, and problems such as difficulty in gene exchange and heritability decline may occur. These plants generally lack the ability to regenerate naturally and coupled with the vulnerability of the distribution environment and the intensification of climate change, there is a problem of limited regeneration [85,[93][94][95].…”

Genomic insights into local adaptation and vulnerability of Quercus longinux to climate change

“…For example, the low spring precipitation and high clay content in habitats in southeastern Taiwan may act as strong environmental stresses that initiate genetic and phenotypic adaptation (e.g., drought resistance) in response to local conditions. In plant species, hostile environmental conditions in edge populations prompt local adaptation processes [102]. The substantial divergence, relatively high genetic diversity, and high offsets of the populations in southern Taiwan indicate that Q. longinux var.…”