关键词: 榕小蜂, 线粒体基因组, 基因重排, 核苷酸多态性； 纯化选择； 氨基酸替换

Abstract:

【Aim】 At present, there are few reports on the mitochondrial genomes of fig wasps. The purpose of this study is to explore whether there are some differences in the evolution of mitochondrial genome (mitogenome) between pollinating fig wasps (PFWs) and non-pollinating fig wasps (NPFWs). 【Methods】 Based on the mitogenomes from 15 fig wasp species, of which the mitogenomes of 11 species were newly determined, we used the comparative mitochondrial genomic method to analyze the sequence and evolutionary characteristics of the mitogenomes of fig wasps. 【Results】 The length of the mitogenomes of 11 fig wasps newly determined ranges from 12 768 to 17 060 bp, and the AT content in the 11 mitogenomes is more than 80%. The AT-skew is negative and the GC-skew is positive in most species except for the non-pollinating fig wasp Philotrypesis tridentata. Frequent mitochondrial gene rearrangement occurs in fig wasps, which may be valuable for phylogenetic analysis of the species. Further analysis of selection pressure indicates that the ω ratios of protein-coding genes (PCGs) in mitogenomes of fig wasps are far less than 1, suggesting that these genes have experienced purifying selection. However, most of the genes in PFWs may have accumulated more nonsynonymous mutations than those in NPFWs. Furthermore, compared with the NPFWs, the mitogenomes of PFWs have more gene rearrangements, and higher nucleotide diversity and amino acid substitution rate. 【Conclusion】 The mitogenome evolution of PFWs is faster than that of NPFWs, which may be related to the significantly different lifestyles or evolutionary histories of the two groups.

Key words: Fig wasps, mitochondrial genome, gene rearrangement, nucleotide diversity, purifying selection, amino acid substitution