Systematics/Phytogeography / Taxonomie/ Section
Li, Qingyan , Guo, Wei , Liao, Wenbo , Macklin, James A. , Li, Jianhua .
Generic Limits in the subtribe Pyrinae (Rosaceae): Evidence from Nuclear and Chloroplast DNA Sequence Data.
Pyrinae, formerly the Maloideae, includes many well-known fruit species such as apple (Malus), pear (Pyrus), quince (Cydonia), loquat (Eriobotrya), chokeberry (Aronia), and serviceberry (Amelanchier). According to Potter et al. (Pl. Syst. Evol. 2007), Pyrinae as a clade consists of 30 genera and close to 1000 species. The potential synapomorphies include prismatic crystals in axial parenchyma, stamens 20, hypanthium adnated to more than half of the ovary, and fruit a pome or polypyrenous drupe. There exist two outstanding issues in the phylogenetics of Pyrinae: (1) what are the intergeneric relationships? (2) what are the generic limits? Campbell et al. (Pl. Syst. Evol. 2007) studied the first problem and concluded that even with about 500,000 bp of DNA sequence there was still little resolution for intergeneric relationships within Pyrinae, indicating an ancient, rapid radiation as suggested by the fossil record. The focus of this study was on the second question. We sampled multiple species and/or accessions of each of the genera and obtained their nrDNA ITS sequences ourselves as well as from the GenBank. Albeit with low bootstrap support, our data provide some insights for generic limits of Pyrinae. Fourteen genera are monophyletic including Amelanchier, Aria, Chaenomeles, Chamaemeles, Chamaemespilus, Cormus, Cotoneaster, Crataegus, Cydonia, Osteomeles, Pseudocyonia, Pyrus, Sorbus, and Torminalis. However, Mespilus is paraphyletic and closely related to the Crataegus clade. Pyracantha does not appear to be monophyletic, while Photinia is highly polyphyletic. Amelanchier is most closely related to Malacomeles and Peraphyllum, whereas Malus sensu lato forms a clade including Eriolobus, Docyniopsis, Heteromeles, and some species of Photinia. We are gathering sequences from low copy nuclear genes and chloroplast non-coding regions to further test the hypotheses hoping to stabilize generic limits of Pyrinae. This study was partially supported by a CNSF grant to WL and a CSC Scholarship to QL.
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1 - Sun Yat-sen University,, School of Life Sciences, Guangzhou, Guangdong, 510275, China
2 - Sun Yat-sen University, School of Life Sciences, Guangzhou, Guangdong, 510275, China
3 - Harvard University Herbaria, Organismal and Evolutionary Biology, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
4 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
nrDNA ITS sequences
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM