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Biochemical Systematics and Ecology 37 (2009) 589–596

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Biochemical Systematics and Ecology
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High genetic differentiation and low genetic diversity in Incarvillea younghusbandii, an endemic plant of Qinghai-Tibetan Plateau, revealed by AFLP markers
Yong Zhu a, Yupeng Geng a, b, *, TashiTersing c, Nian Liu a, Qingbiao Wang a, Yang Zhong a, c, *

Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China Institute of Ecology and Geobotany, School of Life Sciences, Yunnan University, Kunming 650091, China c Institute for Biodiversity Science and Geobiology, Tibet University, Lhasa850000, China

a r t i c l e i n f o
Article history: Received 20 May 2009 Accepted 10 October 2009 Keywords: AFLP Genetic diversity Incarvillea younghusbandii Population structure Qinghai-Tibetan Plateau

a b s t r a c t
Incarvillea younghusbandii Sprague (Bignoniaceae) is a perennial herbaceous plant endemic to Qinghai-Tibetan Plateau. As a species of medical and horticulture importance, I.younghusbandii is threatened by over exploitation and habitat fragmentation. In this study, we analyze the genetic diversity and population structure of I. younghusbandii using amplified fragment length polymorphism (AFLP) markers. Our data reveal very low levels of genetic diversity in seven natural populations across Tibet. Specifically, at population level, the average Nei’s genetic diversityindex (HE) and Shannon’s diversity index (I) were 0.063 and 0.096, respectively. In contrast, high genetic differentiation among populations (Gst ¼ 0.6238, FST ¼ 0.614) is detected. The results of Neighbor-joining cluster, PCO, and STRUCTURE assignment reveal consistent pattern, suggesting seven well-defined genetic groups that are concordant with their geographical origins. The possible mechanismsand implications of these findings for conservation are discussed. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction Qinghai-Tibetan Plateau is the highest and youngest plateau in the world and has been entitled as ‘‘the third pole’’ on earth because of its extremely high altitude (i.e. more than 4000 m). It is also an important biodiversity hotspot, to which more than 1100 species of 20genera of plants are endemic (Wu, 1980, 1987; Wu et al., 1995). These unique alpine plants, however, are now facing great challenges caused by climate change. Previous studies suggest that the vegetative cover and alpine meadows have decreased significantly in the middle and northwest part of the plateau between 1992 and 2002, which may partially due to the altered temperature and precipitationpatterns (Liang et al., 2007). The degradation of alpine ecosystem may cause great threats to many alpine plant species (Jorgenson et al., 2001; Mcguire, 2002). Whether these species can cope with the coming environmental changes will largely depend on their ability to dispersal into new habitats and/or to evolve in situ based on their standing genetic variations (Aitken et al., 2008). In particular,knowledge of the genetic structure of alpine plants provides data on the levels and distribution of genetic variation within/among populations and the clues of long distance dispersal via seeds or pollen flow, thus providing fundamental information for conservation biology (Hamrick and Godt, 1996; Zheng et al., 2008). However, the genetic structure of alpine plants in Qinghai-Tibet Plateau remainspoorly documented.

* Corresponding author at: Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China. Tel.: þ86 21 55664436; fax: þ86 21 65642468. E-mail addresses: (Y.-P. Geng), (Y. Zhong). 0305-1978/$ – see front matter Ó 2009 Elsevier Ltd. All...
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