Abstract Detail

Population Genetics

Qi, Xinshuai [5], Chen, chen [5], Comes, Hans Peter [1], Sakaguchi, Shota [2], Liu, Yihui [5], Tanaka, Nobuyuki [3], Sakio, Hitoshi [4], Qiu, Yingxiong [5].

Contrasting gene genealogies and ecological niche modelling reveal the complex biogeographic history of Cercidiphyllum (Cercidiphyllaceae), a Tertiary relict tree genus endemic to East Asia.

Little is known about the genetic and evolutionary consequences of range fluctuations during the Quaternary for East Asia's Tertiary relict flora. Cercidiphyllum, a prominent member of this flora, comprises two species inhabiting warm-temperate deciduous forests in subtropical China/Japan (C. japonicum) and cool-temperate/subalpine forests in CentralJapan (C. magnificum). Variation in chloroplast DNA and nuclear ribosomal DNA sequences, as well as nuclear microsatellites in 53 populations of Cercidiphyllum was examined to assess the phylogenetic relationships among species, and to explore geographic patterns of molecular variation in relation to Quaternary climate change using ecological niche modeling (ENM). Our results revealed that the two species underwent an allopatric phase of divergence before coming into secondary contact in central Honshu,resulting in the capture of chlorotypes native to C. magnificum by C. japonicum.Divergence dating and coalescent simulations indicate that speciation occurred at the Mio-/Pliocene boundary, while diversification within each species and the phylogeographic processes associated with them occurred within the Quaternary. Cercdiphyllum japonicum likely survived Quaternary ice ages in three major refugia (Southwest China,Southeast China, South Japan), which were linked by gene flow via "steppingstone" populations. Upon climate amelioration, range expansion in China occurred into areas north of the Yangtze from refugial areas around the Sichuan Basin and/or the middle-Yangtze, and from South Japan to North Japan. Postglacial range expansion of the warm-temperate C.japonicum to the very far north of Japan may have been facilitated through introgressive hybridization with its cool-temperate congener, C. magnificum, in central Honshu.

Broader Impacts:

1 - Salzburg University, Department of Organismic Biology, A-5020 Salzburg, Austria
2 - Kyoto University, Graduate School of Agriculture, Kyoto, 6068502, Japan
3 - Forestry and Forest Products Research Institute, Department of Plant Ecology, Ibaraki , 305-8687, Japan
4 - Niigata University, Field Center for Sustainable Agriculture and Forestry, Niigata , 952-2206
5 - Zhejiang University, College of Life sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China

Keywords:
Cercidiphyllum
East Asia
ecological niche modelling
organellar introgression
phylogenetic analyses.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM
Number: PPG001
Abstract ID:378