Genetic structure and phylogeography of a relict tree fern, Sphaeropteris brunoniana (Cyatheaceae) from China and Laos inferred from cpDNA sequence variations: Implications for conservation

Abstract

In this study, we analyzed the genetic structure and phylogeography of Sphaeropteris brunoniana from China and Laos. Combining cpDNA trnL‐trnF and atpB‐rbcL sequence variations, five haplotypes were identified from the 10 investigated populations. Moderate haplotype diversity (h= 0.66580) and low nucleotide diversity (π= 0.23 × 10−3) were detected. The S. brunoniana in Yunnan region had much higher genetic diversity (h= 0.60195, π= 0.35 × 10−3) than that of Hainan–Laos (h= 0.00000, π= 0.00). A high level of genetic differentiation (94.74%) between the two regions was revealed by amova. Nested clade analysis identified two major clusters of the five haplotypes, one clade in the Yunnan region and the other in Hainan–Laos. The analysis indicated that restricted gene flow with isolation by distance and allopatric fragmentation were likely the major processes that shaped the spatial distribution of the haplotypes. The isolated distribution of clades implied the emergence of independent refugia of this species in each region during Quaternary glaciations. The Yunnan populations frequently contained an ancestral haplotype, and most of them harbored other descendent haplotypes. Based on the distribution pattern of haplotypes and the nested clade analysis results, the Yunnan region potentially had several refugia of this species during glacial periods, whereas the Hainan populations were probable new colonizations.

Long-Distance Dispersal after the Last Glacial Maximum (LGM) Led to the Disjunctive Distribution of Pedicularis kansuensis (Orobanchaceae) between the Qinghai-Tibetan Plateau and Tianshan Region

“…as refugia during the Quaternary glacial periods, and then recolonized QTP and its surrounding regions during the interglacial phases or at the end of the Last Glacial Maximum (LGM) [35,90–95]. While the other hypothesis suggested some species may have also survived at QTP and its surrounding regions in situ through the Quaternary [96,97]. Previous studies in NW China showed species survival in East Tianshan Mountains [22] and Ili (Yili) Valley [33] during the Quaternary.…”

Phylogeographic studies of plants in China: Advances in the past and directions in the future

“…Multiple refugia may have remained for these species, at least during the LGM (e.g., Wang et al, 2009b; Jia et al, 2011, 2012; Zhang et al, 2012). In fact, the multiple refugia of SW China remained for the studied species (e.g., Gao et al, 2007; Yuan et al, 2008; Wang & Guan, 2011). In western China, deserts seemed to have promoted the allopatric divergences of the studied species and these diverged populations should have survived in the different refugia during the LGM (e.g., Guo et al, 2010; Wang et al, 2011c; An et al, 2012; Li et al, 2012b, 2012d; Zhang & Zhang, 2012).…”

Identifying a contact zone between two phylogeographic lineages of Clematis sibirica (Ranunculeae) in the Tianshan and Altai Mountains

“…Most parts of China are deemed to have been free of an extensive ice sheet (Shi et al, 2006); however, species still experienced glacial‐time retreats and interglacial recolonizations in response to cold–warm climatic cycles. During glacial episodes, separate refugia during glacial advances are hypothesized to have triggered lineage divergence in many species (Gao et al, 2007; Wang et al, 2009a; Guo et al, 2010; Tang et al, 2010; Li et al, 2011; Wang & Guan, 2011). Likewise, evidence from low levels of genetic diversity indicate that demographic expansion, resulting in the founder effect, has frequently occurred following the onset of interglacial warming (Cun & Wang, 2010; Zhang et al, 2010).…”