Morphological and molecular evidence of natural hybridization in Shorea (Dipterocarpaceae)

Shorea (Dipterocarpaceae) is a large genus in which many closely related species often grow together in Southeast Asian lowland tropical rain forests. Many Shorea species share common pollinators, and earlier studies suggested occurrence of interspecific hybridization and introgression. Here, we sho...

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Bibliographic Details
Published in:Tree genetics & genomes 2011-04, Vol.7 (2), p.297-306
Main Authors: Kamiya, Koichi, Gan, Yik Yuen, Lum, Shawn K. Y, Khoo, Min Sheng, Chua, Siew Chin, Faizu, Nik N. H
Format: Article
Language:English
Subjects:
Biomedical and Life Sciences
Biotechnology
Dipterocarpaceae
Forestry
Forests
GapC
Genomes
Hybridization
Life Sciences
Morphology
Natural hybridization
Original Paper
PgiC
Plant Breeding/Biotechnology
Plant Genetics and Genomics
Pollinators
Rainforests
Shorea
Shorea curtisii
Shorea leprosula
Shorea parvifolia
Southeast Asian tropical rain forest
Tree Biology
Trees
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Summary:Shorea (Dipterocarpaceae) is a large genus in which many closely related species often grow together in Southeast Asian lowland tropical rain forests. Many Shorea species share common pollinators, and earlier studies suggested occurrence of interspecific hybridization and introgression. Here, we show morphological and molecular evidence of hybridization between Shorea species. In the census of all the trees of Shorea curtisii, Shorea leprosula, and Shorea parvifolia (>30 cm dbh) within the 164-ha area of Bukit Timah Nature Reserve in Singapore, we found 21 morphologically recognizable hybrid individuals. All of the putative hybrids could be distinguished obviously from the parental species on the basis of vegetative characters. Population genetic analysis of DNA sequences of two nuclear (GapC and PgiC) and chloroplast (trnL-trnF) regions demonstrated that each of the three species had several species-specific mutations. The nuclear sequences of the putative hybrids were heterozygote at all the species-specific sites between two parental species. Hybrid between S. curtisii and S. leprosula was found most, while S. curtisii × S. parvifolia and S. leprosula × S. parvifolia hybrids were also found. Almost no shared polymorphism between populations of the parental species suggests rarity of introgression. The study indicated that natural hybridization between sympatric Shorea species should not be uncommon, but all of the hybrid individuals were F₁, and the post-F₁ hybrids were considerably rare.
ISSN:1614-2942
1614-2950
DOI:10.1007/s11295-010-0332-8