Divergence time estimation of genus Tribolium by extensive sampling of highly conserved orthologs

Tribolium castaneum, the red flour beetle, is among the most well-studied
eukaryotic genetic model organisms. Tribolium often
serves as a comparative bridge from highly
derived Drosophila traits to other organisms.
Simultaneously, as a member of the most diverse order of metazoans,
Coleoptera,  Tribolium informs us about
innovations that accompany hyper diversity. However, understanding the
tempo and mode of evolutionary innovation requires well-resolved,
time-calibrated phylogenies, which are not available
for Tribolium. The most recent effort to
understand Triboliumphylogenetics used two mitochondrial and
three nuclear markers. The study concluded that the genus may be
paraphyletic and reported a broad range for divergence time estimates.
Here we employ recent advances in Bayesian methods to estimate the
relationships and divergence times among Tribolium
castaneum, T. brevicornis, T. confusum, T.
freemani, and Gnatocerus cornutus using 1368 orthologs
conserved across all five species and an independent substitution rate
estimate. We find that the most basal split
within Tribolium occurred ~86 Mya [95% HPD 85.90–87.04
Mya] and that the most recent split was between T.
freemani and T. castaneum at ~14
Mya [95% HPD 13.55-14.00]. Our results are consistent with
broader phylogenetic analyses of insects and suggest that Cenozoic climate
changes played a role in the Tribolium diversification.