Or83b-like基因内含子2个体内及个体间长度杂合现象揭示了Philotrypesis sp.的进化不稳定性

佩妃延腹小蜂Philotrypesis pilosa和Philotrypesis sp.是寄生在对叶榕Ficus hispida L.上的同属非传粉榕小蜂，二者可能拥有最近共同祖先。榕小蜂利用嗅觉对寄主榕树的专一性识别可能是其产生交配前隔离的重要机制，Or83b-like基因是一类在不同昆虫间高度保守的非典型嗅觉受体基因，研究其内含子序列对解决近缘种的物种形成和进化方向问题有重要意义。本文采用PCR法对这两种小蜂的Or83b-like基因进行分析。结果表明：该两种小蜂的Or83b-like基因编码区核苷酸序列及推导的氨基酸序列一致度非常高，分别为98.2%和99.03%，内含子序列平均一致度也很高，为84.5%左右，进一步证明二者亲缘关系很近。我们在P. sp.的Or83b-like基因部分内含子序列中发现个体内及个体间具长度杂合现象(LVHs)，但P. pilosa却不存在。据此推测，P. pilosa为进化上已经趋于稳定的物种，而P. sp.则没有完全稳定。

Inter- and intra-individual length-variant heterozygotes of intron 2 in Or83b-like gene unveil evolutionary instability in Philotrypesis sp. (Hymenoptera: Chalcidoidea: Pteromalidae)

The two non-pollinating fig wasps on Ficus hispida L.,Philotrypesis pilosa and P.sp.,might share the latest common ancestor.Host plant recognition using olfactory system by fig wasps may act as a strict pre-mating isolation mechanism.We investigated the introns of the atypical olfactory receptor gene Or83b-like,which is remarkably conserved among many insects and can be used to unveil speciation and the direction of differentiation in closely related species.The PCR results showed that the nucleotide identity in the coding regions and the identity of the deduced amino sequences between the two fig wasps were 98.2% and 99.03%,respectively,and that of the introns 84.5% on average.The high identity further confirms the close relationship between the two fig wasps.However,inter-and intra-individual length-variant heterozygotes in some introns in P.sp.were observed,but not in P.pilosa.It is so inferred that P.pilosa might have become stable as a species,while P.sp.may be still in the process of speciation.