Chin J Plant Ecol ›› 2007, Vol. 31 ›› Issue (2): 291-299.DOI: 10.17521/cjpe.2007.0033

• Research Articles • Previous Articles     Next Articles


MAO Jian-Feng1,2, LI Yue3, LIU Yu-Jun3, LIU Hao4, WANG Xiao-Ru1,*()   

  1. 1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
    3Key Laboratory of Genetic and Breeding in Forest Trees and Ornamental Plants, Beijing Forestry University, Beijing 100083, China
    4College of Agriculture, Tibet University, Linzhi, Tibet 860000, China
  • Received:2005-10-17 Accepted:2006-03-03 Online:2007-10-17 Published:2007-03-30
  • Contact: WANG Xiao-Ru


Aims Pinus densata is an important forest species in the high mountains of the southeastern Tibetan Plateau. Previous investigations demonstrated that this pine originated through natural hybridization between P. yunnanensis and P. tabulaeformis. The mechanisms underlying this hybrid speciation and especially its adaptive evolution are poorly understood. Reproductive fitness plays a critical role in hybrid speciation; however, the fitness of P. densata in the high plateau environment has not been investigated.

Methods We investigated 13 cone and seed characters, related to reproductive potential of the species, from six representative populations distributed throughout its natural range. The 13 characters are cone length, number of scales per cone, number of fertile scales, cone scale density, fertile scale density, ratio of fertile scales, number of seeds per cone, seed length, length of seed wing, total seed length per cone, total length of seed wing per cone, seed productivity per cone and ovule abortion rate. Patterns of variation of these characters were analyzed using one-way ANOVA and correlated to geo-ecological factors of each population.

Important fingdings Characters, such as cone length, total number of scales in a cone and number of seeds per cone in P. densata were similar to that in P. tabulaeformis, P. yunnanensis and several other species of Pinus. The maximum mean value of seed productivity per cone was 74%. One-way ANOVA showed significant (p<0.01) differentiation in all 13 characters among the six populations. Correlation analysis between cone and seed characters and geo-ecological factors indicated that total number of cone scales, number of fertile scales, number of seeds per cone and ratio of fertile scales were negatively correlated with latitude and seed productivity was positively correlated with longitude and ecological gradient axes. All results suggested thatP. densata as a hybrid species is not inferior in reproductive fitness in the plateau environment. The patterns of geographic variations in cone and seed characters seem to be related to the genetic background and divergent ecological environments of the populations.

Key words: hybrid, reproductive characters, population differentiation, geographic variation, ecological adaptation