Phylogeography of the endangered Cathaya argyrophylla (Pinaceae) inferred from sequence variation of mitochondrial and nuclear DNA

Abstract

Cathaya argyrophylla is an endangered conifer restricted to subtropical mountains of China. To study phylogeographical pattern and demographic history of C. argyrophylla, species-wide genetic variation was investigated using sequences of maternally inherited mtDNA and biparentally inherited nuclear DNA. Of 15 populations sampled from all four distinct regions, only three mitotypes were detected at two loci, without single region having a mixed composition (G(ST) = 1). Average nucleotide diversity (theta(ws) = 0.0024; pi(s) = 0.0029) across eight nuclear loci is significantly lower than those found for other conifers (theta(ws) = 0.003 approximately 0.015; pi(s) = 0.002 approximately 0.012) based on estimates of multiple loci. Because of its highest diversity among the eight nuclear loci and evolving neutrally, one locus (2009) was further used for phylogeographical studies and eight haplotypes resulting from 12 polymorphic sites were obtained from 98 individuals. All the four distinct regions had at least four haplotypes, with the Dalou region (DL) having the highest diversity and the Bamian region (BM) the lowest, paralleling the result of the eight nuclear loci. An AMOVA revealed significant proportion of diversity attributable to differences among regions (13.4%) and among populations within regions (8.9%). F(ST) analysis also indicated significantly high differentiation among populations (F(ST) = 0.22) and between regions (F(ST) = 0.12-0.38). Non-overlapping distribution of mitotypes and high genetic differentiation among the distinct geographical groups suggest the existence of at least four separate glacial refugia. Based on network and mismatch distribution analyses, we do not find evidence of long distance dispersal and population expansion in C. argyrophylla. Ex situ conservation and artificial crossing are recommended for the management of this endangered species.

Genetic diversity of relictual and endangered plant Abies ziyuanensis (Pinaceae) revealed by AFLP and SSR markers

“…The low genetic diversity within populations and high genetic differentiation among populations we observed in A. ziyuanensis are similar to that of another relictual endangered conifer species in China, Cathaya argyrophylla (Wang et al 1996;Ge et al 1998), which may be partially ascribed to the evolutionary history (Wang and Ge 2006). Specifically, the present distribution of A. ziyuanensis is restricted to several isolated alpine habitats with cold microclimates in South China (Ning et al 2005, Zhang et al 2004).…”

Phylogeography of Eurasian Larix species inferred from nucleotide variation in two nuclear genes

“…However, the level of nucleotide diversity revealed in our study was in the same order or slightly higher than those reported for other conifers e.g., Cryptomeria japonica (π sil = 0.0039) over seven loci (Kado et al, 2003), Cathaya argyrophylla (π sil = 0.0024) (Wang and Song, 2006), Pinus tabuliformis, P. yunnanensis and P. densata (π sil = 0.0087 ~ 0.0128 over 7 loci, (Ma et al, 2006). It thus appears that contrary to previous suggestions Larix species have levels of nucleotide diversity comparable to other conifers.…”

Chloroplast DNA phylogeographic analysis reveals significant spatial genetic structure of the relictual tree Davidia involucrata (Davidiaceae)

“…This region has been presumed to be a long-term refuge for plant species in general because of its high diversity and endemism (Ying et al 1993;Wu and Wu 1996;Ying 2001;Wang et al 2009). Many ancient plant species, such as Cathaya argyrophylla, Emmenopterys henryi, C. japonicum, Tetracentron sinense, Ginkgo biloba, Thuja sutchuenensis and Metasequoia glyptostroboides, are found in this region (Ying et al 1993;Wang and Ge 2006;Gong et al 2008). Rather unexpectedly in this study, haplotype H13 grouped in the same lineage as H1 (HPGI) but was distributed outside of the Wuling Mts.…”