Genetic structure of the endemic Papaver occidentale indicates survival and immigration in the Western Prealps

Abstract

Climatic oscillations of the Quaternary rapidly compelled plant species to shift their geographical range. How alpine plant species responded to climate change, however, remains elusive and remnants of the cold-adapted flora that currently strive in restricted ranges as small, isolated populations have been particularly overlooked. To address the evolutionary history of such a ‘glacial relict’, we here sampled and genotyped all known native populations of a narrow endemic species from the northwestern Alps, Papaver occidentale, as well as closely related taxa with double digest restriction-site Associated DNA (ddRAD) sequencing. Spatial patterns of genetic variation across populations coupled with insights from climatic niche modelling through time address underpinings of the long-term persistence of the species in face of climate changes. Evidence from population genetics and ecological modelling indicates that P. occidentale likely persisted through the last glacial maximum outside of the Western Prealps and that a major lineage recolonized the area from lower elevation, external regions. Differentiated lineages at the Northern margins of the species distribution range highlight highly divergent and geographically restricted populations that include considerable share of private markers and may indicate local glacial survival in isolated conditions. Our data thus imply that processes having shaped intraspecific spatial genetic structure within the Alps can be complex and lead to mosaic of populations with a mixed-history of local survival and immigration. A better understanding of spatio-temporal aspects of range contraction–expansion is crucial to shed light on processes underlying the evolution of remnant populations of such endemic species and set conservation priorities considering current climate changes.

Climate Change and Alpine Screes: No Future for Glacial Relict <em>Papaver occidentale</em> (Papaveraceae) in Western Prealps

“…Such a domination in this region is an important discovery of the present study, since the only reports on P. occidentale available to date, attributed regions of Fribourg and Vaud as the main distribution centers of this taxon [38]. Furthermore, the five populations of the canton of Bern represent a unique genetic composition, being highly differentiate in comparison with all the other populations [34]. These results should be therefore taken into consideration in redistribution of the conservation responsibilities and priorities for the concerned regions and administrative units.…”

“…Information about all known locations of P. occidentale was obtained from Info Flora (www.infoflora.ch), as well as elucidated from the literature [32,36], from the unpublished reports [38,39] and from personal communications of local experts (B. Clément from the Botanical Garden of the University of Fribourg and D. Jordan from France). The populations from the Swiss canton of Lucerne were identified as belonging to P. sendtneri [34], and were not taken into consideration in the present study. All information was gathered, duplicates as well as non-precise locations were removed, and the remaining information was used to conduct the populations sampling.…”

“…However, recent molecular data indicate, that both local survival and immigration from edge alpine refugia played an important role during the recolonization of the Western Prealps by P. occidentale, leading to a complex genetic pattern [34]. Papaver occidentale is clearly in refugial situation today.…”

“…sendtneri (both north-eastern Alps), and P. tatricum (Tatra mountains in the Carpathians) [30][31][32][33][34]. The recolonization history of the Prealps by this taxon after the last glaciation was complex and the present genetic structure of P. occidentale is a result of a mixture of local survival and immigration [34]. Despite of its priority status in many regions of Switzerland and France [35] and its symbolic value to some regions [36], the plant was never studied across its entire distribution area.…”

Climate Change and Alpine Screes: No Future for Glacial Relict Papaver occidentale (Papaveraceae) in Western Prealps

“…Information about all known locations of P. occidentale was obtained from Info Flora (www.infoflora.ch), as well as elucidated from the literature [32,36], from the unpublished reports [38,39], and from personal communications of local experts (B. Clément from the Botanical Garden of the University of Fribourg and D. Jordan from France). The populations from the Swiss canton of Lucerne were identified as belonging to P. sendtneri [34] and were not taken into consideration in the present study.…”