Genomic divergence of the Italian drywood termites Kalotermes italicus and K. flavicollis (Blattodea Kalotermitidae): insights from genome skimming

Genome skimming provides a cost-effective and rapid method for phylogenomic studies, enabling the reconstruction of mitochondrial genomes, nuclear markers, and transposable element profiles. We applied this method to Kalotermes italicus, successfully reconstructing its mitochondrial genome and performing phylogenetic analysis, which confirmed a close evolutionary relationship with Kalotermes flavicollis. Mitochondrial gene divergence between the two species ranges from 2.3 to 12%, while a lower divergence was observed across BUSCO genes, ribosomal DNA, and ultraconserved elements (UCEs). This could explain the observed high colony fusion rates and potential hybridization. Analysis of transposable elements (TEs) revealed a similar genomic composition between the two species. However, K. italicus showed a marked recent TEs activity, which is consistent with the inferred speciation time (~ 7 million years ago). This suggests a link between TEs dynamics and demographic processes, such as population bottlenecks, occurring at speciation. Our findings provide new insights into the evolutionary dynamics of Italian drywood termites and highlight the utility of genome skimming for studying termite biodiversity.