Abstract:
BACKGROUND: Gene duplication events play an important role in the evolution and adaptation of organisms.
Duplicated genes can arise through different mechanisms, including whole-genome duplications (WGDs). Recently,
WGD was suggested to be an important driver of evolution, also in hexapod animals.
RESULTS: Here, we analyzed 20 high-quality hexapod genomes using whole-paranome distributions of estimated
synonymous distances (KS), patterns of within-genome co-linearity, and phylogenomic gene tree-species tree
reconciliation methods. We observe an abundance of gene duplicates in the majority of these hexapod genomes,
yet we find little evidence for WGD. The majority of gene duplicates seem to have originated through small-scale
gene duplication processes. We did detect segmental duplications in six genomes, but these lacked the withingenome co-linearity signature typically associated with WGD, and the age of these duplications did not coincide
with particular peaks in KS distributions. Furthermore, statistical gene tree-species tree reconciliation failed to
support all but one of the previously hypothesized WGDs.
CONCLUSIONS: Our analyses therefore provide very limited evidence for WGD having played a significant role in the
evolution of hexapods and suggest that alternative mechanisms drive gene duplication events in this group of
animals. For instance, we propose that, along with small-scale gene duplication events, episodes of increased
transposable element activity could have been an important source for gene duplicates in hexapods.
