Phylogeography of Trochodendron aralioides (Trochodendraceae) in Taiwan and its adjacent areas

Abstract

Phylogeography (Avise et al., 1987) is a branch of historical biogeography that involves determining the history of taxa in space and time by integrating the phylogenetic and geographical patterns. This is carried out especially at the level of species complex or intraspecific populations to reveal how the present distribution patterns of taxa have been shaped by geological events or other factors. As the taxon is at species level, the scale in time and space is much shorter and smaller than the study of generic or higher taxonomic levels, and is suitable for revealing the taxon's history from the Quaternary, < 2 Myr.The origin of the island Taiwan can be traced to the Pliocene, about 4-5 Ma, when it began to emerge. Taiwan quickly became the present shape at about 2 Ma through mountain building (Ho, 1982;Shaw, 1996). It is thus suitable to study Taiwan's species based on phylogeography. Taiwan ABSTRACT Aim This paper described current phylogeographical patterns of chloroplastic DNA variation of Trochodendron aralioides, a temperate tree species, and inferred its possible refugium in Taiwan. This information was compared with the known phylogeographical pattern of subtropical tree species.Location A total of 24 populations were sampled including 20 from Taiwan, two each from the Ryukyus and Japan.Methods A haplotype network was constructed by computer program TCS, various parameters of genetic diversity were calculated and neutrality was tested by computer program DnaSP. To examine the similarity of genetic structure among populations, a maximum parsimony tree was reconstructed by computer program PAUP*. The results of isozyme of T. aralioides from a previous publication were incorporated into this study to infer the phylogeographical history.Results Nine haplotypes according to six substitutions, two indels and one inversion of the two cpDNA intergenic spacer fragments (petG-trnP and petApsbJ) of T. aralioides were recognized. Genetic structure of the population of Japan is totally different from those of Taiwan and the Ryukyus. In Taiwan, the genetic structure was differentiated among populations revealed by G st ¼ 0.700 and N st ¼ 0.542, and the population genetics was clearly spatially structured. Two population groups were recognized. The first group was distributed islandwide and extended to the Ryukyus. The second group contained five of the seven known haplotypes, and was restricted to the area between latitude 24°46¢ and 24°06¢ N.Conclusions In Taiwan, north-central area between latitude 24°46¢ and 24°06¢ N is potentially a refugium during the last glaciations. This finding is contradicted to subtropical species as Cyclobalanopsis glauca.

Two genetic divergence centers revealed by chloroplastic DNA variation in populations of Cinnamomum kanehirae Hay

“…glauca (Huang et al 2002;Lee et al 2006;Shih et al 2006), T. aralioides (Huang et al 2004), Cunninghamia konishii , Cas. carlesii (Cheng et al 2005), Machilus thunbergii (Wu et al 2006), M. kusanoi (Wu et al 2006), Abies kawakamii (Shih et al 2007), and C. kanehirae (this study).…”

“…4), and includes the Hsuehsahan, Shiouhluan, Ssuyan, Hakannishan, Lishan, Tahu, Tashueshan, and Huisun populations for the seven respective tree species. Species here include several temperate species: T. aralioides (Huang et al 2004), Cu. konishii (Chung et al 2004), Cas.…”

“…Using a similar strategy, Huang et al (2004) inferred that the north-central region, west of the central mountain range (CMR) was a potential refugium for Trochodendron aralioides, a temperate species, during the last glaciation. Cheng et al (2005) proposed that the above regions might have been potential refugia for Castanopsis carlesii, another widespread species in Taiwan according to the average F ST values of individual populations compared to the remaining populations, which means where the most-divergent populations are located.…”

Geographical traceability of an important tropical timber (Neobalanocarpus heimii) inferred from chloroplast DNA

“…Chloroplast DNA is thought to evolve slowly, with low mutation and recombination rates, and is known to be maternally inherited in most angiosperms. Maternally inherited DNA markers generally reveal much greater genetic structure in comparison with biparentally inherited nuclear markers (Petit et al, 1993a,b) and these markers have been successfully applied to identify possible glacial refugia and species migration routes of many plant species (Huang et al, 2004;Cheng et al, 2005;Fjellheim et al, 2006;Shephard et al, 2007). In principle, the geographical origin of wood samples can be checked with the cpDNA markers that show enough geographical structure.…”

Nested clade phylogeographical analysis of the finless porpoise (Neophocaena phocaenoides) inhabiting Chinese and Japanese coasts

“…NCPA has been advantageous for disentangling contributions of historical processes and current gene flow to the observed patterns of haplotype composition. This method has been instrumental in phylogeographical research of humans (Hammer et al, 1998), reptiles (Paulo et al, 2002;Amato et al, 2008), fishes (Weiss et al, 2002), insects (Contreras-Díaz et al, 2003), mollusks (Turner et al, 2000;Wilke and Pfenninger, 2002), coelenterates (Márquez et al, 2002), and plants (Huang and Lin, 2006).…”