Chin J Plant Ecol ›› 2013, Vol. 37 ›› Issue (2): 150-163.DOI: 10.3724/SP.J.1258.2013.00016

Special Issue: 青藏高原植物生态学:种群生态学

• Research Articles • Previous Articles     Next Articles

Seedling performance of Pinus densata and its parental population in the habitat of P. tab- uliformis

LIANG Dong1, MAO Jian-Feng2, ZHAO Wei2, ZHOU Xian-Qing3, YUAN Hu-Wei1, WANG Li-Ming2, XING Fang-Qian1, WANG Xiao-Ru1, LI Yue1,*()   

  1. 1Key Laboratory of Genetic and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, National Engineering Laboratory for Tree Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China
    2State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    3Qigou State-owned Forest Farm in Hebei Province, Pingquan, Hebei 067509, China
  • Received:2012-08-28 Accepted:2013-01-09 Online:2013-08-28 Published:2013-01-31
  • Contact: LI Yue

Abstract:

Aims Pinus densata is the natural diploid hybrid of P. tabuliformis and P. yunnanensis, and is one of a few known examples of homoploid hybrid speciation. In order to describe the adaptive and growth characteristics among the three pine species at seedling stage and clarify the role of ecological selection in interspecific isolation between hybrid and parental species, we conducted a common garden comparative analysis of fitness traits at seedling stage in this species complex.
Methods We investigated 14 adaptive and growth characters in seedlings from 25 representative populations of the three pine species in a typical habit of P. tabuliformis. The 14 traits are germination rate, seedling survival in Aug., Sept. and Nov. 2011, winter survival rate of one-year old seedlings, seedling survival rate in Oct. 2012, rates of bud-set in Nov. 2011 and Oct. 2012, the proportion of yellow, green and purple seedlings, seedling height, ground diameter and crown height of seedlings. Patterns of the variation of these characters were analyzed using multi-factor nested analysis of variance and correlated to geographical factors of each population.
Important findings Most of the traits were significantly differentiated among species and among populations at seedling stage, and the large amount of variance were partitioned among species or among populations. Germination rate, the rates of bud-set in two years, and the survival rate in Oct. 2012 of two-year old seedlings were the best indicators of among-species divergence. P. tabuliformis showed the highest values in most of the traits and appeared as more fit in its native habits than the other two pines. P. yunnanensis was at disadvantage in several critical traits, e.g. the survival rates of Aug., Sept., Nov. 2011 and rates of bud-set in two years. Most of one-year old seedlings of P. yunnanensis have not bud-set at the end of Nov. and the proportion of yellow seedlings were highest and its survival rate in Oct. 2012 was zero, which illustrates its low fitness in P. tabuliformis habitat. The hybrid pine, P. densata was intermediate between the parental species in most of traits except indice of the proportion of purple seedlings. The populations from the ancestry hybrid zone in the northeast of P. densata range coped with the test site environment better than the populations from the western range. Our study highlights the role of ecological selection in speciation of this homoploid hybrid pine.

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Key words: growth and development, Pinus densata, Pinus tabuliformis, Pinus yunnanensis, adaptation