Genetic Variation and Phylogeographical Patterns in Alsophila podophylla from Southern China Based on cpDNAatpB-rbcL Sequence Data

Abstract

Chloroplast DNA (cpDNA) atpB-rbcL intergenii spacers o\ individuals of Alsophila podophylla, collected from eight relict populations distributed in Hainan and Guangdong Province, southern China, were sequenced. Sequence sizes were 726 or 727bp. Base composition had a high A+T content of 62.67-63.00%. Sequences were assessed as evolutionarily neutral 0.76638, P > 0.10). Eight haplotypes were identified based on a statistical parsimony algorithm. A high level of haplotype diversity (h = 0.618) and a low nucleotide diversity [Dij = 0.00208) were detected in A. podophylla. Populations from Hainan shared common haplotypes with those from Guangdong. A network and a NJ tree constructed from cpDNA haplotypes both suggested a close genetic relationship among populations distributed in Hainan and Guangdong. Observed F ST (=0.10537), gene flow Nm (=2.12), AMOVA (Only 0.49% of variation was partitioned among regions, P -0.09), and DNA divergence data cnnsislciith indicated that no geographical differentiation occured at the interregional level. Geographic isolation has not yet resulted in population differentiations within A. podophylla populations in Hainan and Guangdong. Phylogeographical patterns of atpB-rbcL haplotypes demonstrate a 'star-like' feature, which means that populations of A. podophylla have experienced population expansion, and, since then there has been insufficient time to form a more complicated population structure. The majority of haplotypes coalesced near the tip of the NJ tree, indicating recent coalescence events as well. l analysis of atpB-rbcL sequences of A. podophylla.Alsophila podophylla Hook, is a small tree fern belonging to Alsophila subgenus Gymnosphaera of the Cyatheaceae (Xia, 1989). With erect or tilted trunks, it averages 2 m in height and has 2-pinnate-pinnatind fronds at the apex; its sori are round, lack indusia, and are located on raised receptacles positioned at the base of veins (Chen, 1964). Cyatheoids were globally distributed during the middle Mesozoic. Due to subsequent geologic and climatic changes, many of their ancestral species became extinct. Only some survived in tropical and subtropical montane zones with relictual distributions (Lucansky, 1974; Willis and McElwain, 2002). Extant A. podophylla are mainly restricted to rain forests at altitudes of 350-700 m, growing on shaded meadows, wetlands or by streamsides.

Population differentiation and phylogeographic pattern of a relict species, Conandron ramondioides (Gesneriaceae), revealed from sequence polymorphism and haplotypes of the CYCLOIDEA gene

“…If so, then the isolation of the present‐day populations between Taiwan and the mainland might have begun approximately 5 Mya. In contrast, disruption to the mainland populations would have occurred much later, possibly not until the glaciation of the Pleistocene, which resulted in considerable population reduction and habitat fragmentation of numerous species of the tertiary humid‐temperate forest in central and eastern mainland China, as well as Taiwan Island (Wu & Wang, 1983; Shen, 1994; Gong et al, 2008; Yu & Chou, 2001; Wang et al, 2004b; Su et al, 2005).…”

Complete chloroplast genome of the tree fern Alsophila podophylla (Cyatheaceae)

“…It can distinguish from other tree ferns by its nearly entire pinnules, basal pinna with a long stalk, and lamina with a conform terminal pinna. As a relic species, the distribution range of A. podophylla had drastically reduced during the Quaternary glaciation events (Zhou et al 2004;Su et al 2005). In China, its extant individuals are mainly restricted to rain forests at an altitude of 350-700 m (Su et al 2005;Zhang and Nishida 2013).…”

“…As a relic species, the distribution range of A. podophylla had drastically reduced during the Quaternary glaciation events (Zhou et al 2004;Su et al 2005). In China, its extant individuals are mainly restricted to rain forests at an altitude of 350-700 m (Su et al 2005;Zhang and Nishida 2013). Alsophila podophylla represents a core member to deal with the classification and phylogeny of Cyatheaceae (Ching 1978;Wang et al 2003), acquirement of its whole chloroplast (cp) genome sequence will facilitate the chloroplast phylogenomics of Cyatheaceae.…”

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

“…The nucleotide diversity of this species was far less than that of other surveyed tree ferns, viz. Alsophila spinulosa (π= 11.30 × 10 −3 , atp B‐ rbc L; π= 22.63 × 10 −3 , trn L‐ trn F) and A. podophylla (π= 2.08 × 10 −3 , atp B‐ rbc L) (Su et al, 2004, 2005a, 2005b). At a regional level, the Yunnan populations had much higher genetic diversity than that of Hainan–Laos.…”