Elongation Factor-1a Occurs as Two Copies in Bees: Implications for Phylogenetic Analysis of EF-1a Sequences in Insects

We report the complete sequence of a paralogous copy of elongation factor-1a (EF-1a) in the honeybee, Apis mellifera (Hymenoptera: Apidae). This copy differs from a previously described copy in the positions of five introns and in 25% of the nucleotide sites in the coding regions. The existence of two paralogous copies of EF-1a in Drosophila and Apis suggests that two copies of EF-1a may be widespread in the holometabolous insect orders. To distinguish between a single, ancient gene duplication and parallel, independent fly and bee gene duplications, we performed a phylogenetic analysis of hexapod EF-1a sequences. Unweighted parsimony analysis of nucleotide sequences suggests an ancient gene duplication event, whereas weighted parsimony analysis of nucleotides and unweighted parsimony analysis of amino acids suggests the contrary: that EF-1a underwent parallel gene duplications in the Diptera and the Hymenoptera. The hypothesis of parallel gene duplication is supported both by congruence among nucleotide and amino acid data sets and by topology-dependent permutation tail probability (TPTP) tests. The resulting tree topologies are also congruent with current views on the relationships among the holometabolous orders included in this study (Diptera, Hymenoptera, and Lepidoptera). More sequences, from diverse orders of holometabolous insects, will be needed to more accurately assess the historical patterns of gene duplication in EF-1a.