Signatures of functional constraint at Fgfr1a Genes in schizothoracine fishes (Pisces: Cypriniformes): The dermal skeleton variation adapted to high-altitude environments.

Fishes harbor a huge resource of phenotypic diversity and are useful for understanding the genetic basis of morphological variation. However, it is difficult to transfer classical genetic mapping to most non-model species. In this study, we performed a comparative sequence analysis of Fgfr1a to first interpret the evolution of this candidate scale-loss gene in 15 schizothoracine fishes with various scale phenotypes. While considerable amino acid (AA) substitutions were observed, molecular evolution analysis indicates that the overall coding regions were subject to functional constraint. We also identified extra copies of Fgfr1a in 4 scale-loss fishes and detected accelerated evolution in one AA substitution specific to these duplicates. We speculate that Fgfr1a had accumulated mutations in the ancestral lineage of scale-loss schizothoracine fishes before experiencing duplication events, which was further followed by the diversification of species. In silico mutation analysis predicted deleterious effects of the mutations while no disruptive molecular mechanism was detected. Collectively, our results highlight the important role of Fgfr1a gene in the adaptive evolution of schizothoracine fishes during their radiation in the Qinghai-Tibetan Plateau.

The complete mitochondrial genome sequence of Platypharodon extremus (Cypriniformes: Cyprinidae).

Platypharodon extemus is a monotypic species of Schizothoracine fishes and it was listed as Endangered species in the "China Red Data Book (Pisces)", Vulnerable (V) by the National Environmental Protection Agency and Endangered Species Scientific Commission. So far, little mitochondrial genome information of this genus has been described. In this study, we obtained the complete mitochondrial DNA genome sequences of this species. The mitogenome was 16,668 bp in length, which consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 2 noncoding regions. The base composition of this mitochondrial genome was 28.6% A, 27.3% T, 18.2% G, 25.9% C, with a high A + T content (55.9%). The complete mitochondrial genome of P. extremus would be of great utility in the phylogenetic analysis of the schizothoracine fishes and also provide meritorious insights into the deeper problems of the phylogenic analysis.