Chromosome-level genome of Capitulum mitella reveals an ancient whole-genome duplication event and intertidal adaptation of barnacles

Barnacles are the only sessile crustaceans inhabiting intertidal zone, an
extremely stressful environment for sessile organisms. Herein, we report
the chromosome-level genome of a stalked barnacle, Capitulum mitella,
which is a dominant intertidal cirripede of the west Pacific Ocean coast.
After comprehensive comparative genomic analyses, it is the first time to
find an ancient whole-genome duplication (WGD) event that preceded the
divergence of Lepadomorpha and Sessilia approximately 237 million years
ago. The retained duplicated genes of WGD are primarily enriched in many
environmental information processing pathways, shedding light on its
adaptive evolution of intertidal sessile life. In addition, transcriptomic
and metabolomic sequencing and analyses of C. mitella indicated that the
upregulation of some expanded anti-stress factors and accumulation of
acyl-carnitines help barnacles adapt to stressful intertidal conditions.
Therefore, this study provides a valuable resource for understanding the
unique intertidal adaptation mechanism of sessile crustaceans and reveals
novel WGD events in invertebrates.