3.4 Genome evolution
To better understand the evolutionary history of C. undulatus , we
identified single-copy orthologs by clustering homologous gene sequences
from L. bergylta , S. melops , O. niloticus , A.
percula , D. rerio , S. anshuiensis , C. semilaevis ,G. aculeatus , O. latipes , B. pectinirostris ,L. maculates , T. rubripes , and C. milii . As a
result, 619 single-copy genes and 22,286 genes from 15,410 families were
identified in C. undulatus (Fig. 6A). Next, we used the coding
sequences of 619 single-copy genes to construct a phylogenetic tree and
determine divergence times. According to the phylogenetic analysis,C. undulatus was clustered together with S. melops andL. bergylta , belonging to the Labrida family. C. undulatusdiverged from the common ancestor with G. aculeatus and L.
maculates around 92.28 Mya (Fig. 6B). Our results are consistent with
major percomorph subclade (Labrida family included) diversification,
which occurred approximately 85-100 Mya in the Late Cretaceous period
(Alfaro et al. 2018). C. undulatus diverged from the
common ancestor with L. bergylta and S. melops around
58.37 Mya. This calibration time is believed to be the initial
diversification of Labridae; subsequently, the pharyngeal jaw
accelerated adaptive radiation of the Labrid ecomorphological diversity
(Alfaro et al. 2009).