Insects are part of the earliest faunas that invaded terrestrial environments and are the first organisms that evolved controlled flight. Nowadays, insects are the most diverse animal group on the planet and comprise the majority of extant animal species described. Moreover, they have a huge impact in the biosphere as well as in all aspects of human life and economy; therefore understanding all aspects of insect biology is of great importance. In insects, as in all cells, translation is a fundamental process for gene expression. However, translation in insects has been mostly studied only in the model organism Drosophila melanogaster. We used all publicly available genomic sequences to investigate in insects the distribution of the genes encoding the cap-binding protein eIF4E, a protein that plays a crucial role in eukaryotic translation. We found that there is a diversity of multiple ortholog genes encoding eIF4E isoforms within the genus Drosophila. In striking contrast, insects outside this genus contain only a single eIF4E gene, related to D. melanogaster eIF4E-1. We also found that all insect species here analyzed contain only one Class II gene, termed 4E-HP. We discuss the possible evolutionary causes originating the multiplicity of eIF4E genes within the genus Drosophila. 1. Introduction Insects are the most diverse animal group on Earth and comprise over half of all extant described species, dominating thus all terrestrial ecosystems [1–4]. Winged insects were the first organisms that evolved controlled flight, some 120, 200, and 300 million years (Myr) before flying reptiles, birds, and bats, respectively. Indeed, wings are believed to have led largely to the spectacular diversification of insects because they were able to explore and invade all terrestrial ecosystems, escape predators, and exploit scattered resources [2, 5]. Many studies show that insect diversity has been also strongly shaped by other evolutionary and ecological processes, including their relative ancient geological age, low extinction rate, ecological niches occupancy, sexual selection, and sexual conflict [1]. Insects originated 434–421？Myr ago during the Silurian Period, and it is suggested that earliest terrestrial faunas already included wingless insects [2, 5, 6]. Indeed, the aquatic-terrestrial transition of insect ancestors is associated with the earliest vascular land plants fossils. Thus, it is thought that true insects evolved from an aquatic arthropod that formed an ecological association with the earliest vascular plants and subsequently both lineages coevolved
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