ScienceAsia 29 (2003): 013-020 |doi: 10.2306/scienceasia1513-1874.2003.29.013

Molecular Characterization of the Divergence of Rare Species of the Genus Afgekia (Papilionoideae, Tribe Tephrosieae) by RAPD Markers and Nucleotide Sequences Analysis

Preecha Prathepha^a,* and Visut Baimai^b

ABSTRACT: The two taxa of the genus Afgekia, namely Afgekia sericea and A. mahidolae are endemic to Thailand. The former species is widely distributed in northeastern Thailand, while the latter has been found only in western Thailand. We previously reported on morphological and cytological data and proposed that these two taxa resulted from allopatric speciation of an ancestral species in different geographical populations. This work provides further characterization of the relationships between them at the DNA level. According to RAPD data, A. sericea and A. mahidolae exhibited a high value of genetic distance (D= 0.55). Furthermore, the nucleotide sequences of the internal transcribed spacer of nuclear ribosomal DNA (nrDNA ITS1 and ITS2) and the chloroplast rbcL gene of the two taxa were compared. For the ITS regions, the sequence divergence of these spacers between the taxa was very high. This indicated that these two species are probably not recently diverged. For the partial nucleotide sequence of rbcL gene, both the divergence at the nucleotide and amino acid level were higher than expected (5.6% for nucleotide, 5.1% for amino acid). These data are likely to reflect the evolutionary process which led to the present patterns of phenotypic and genetic variation between the two taxa.

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a Department of Biotechnology, Faculty of Technology, Mahasarakham University, Mahasarakham 44000 Thailand.
b Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400 Thailand.

* Corresponding author, Email: preecha.p@techno.msu.ac.th

Received 22 Feb 2001, Accepted 7 Oct 2002