Although there are many examples of color evolution potentially driven by sensory drive, only few studies have examined whether distinct species inhabiting the same environments evolve similar body colors via shared sensory mechanisms. In this study, we tested whether two sympatric freshwater fish taxa, halfbeaks of the genus Nomorhamphus and ricefishes of the genus Oryzias in Sulawesi Island, converge in both body color and visual sensitivity. After reconstructing the phylogeny separately for Nomorhamphus and Oryzias using transcriptome‐wide sequences, we demonstrated positive correlations of body redness between these two taxa across environments, even after phylogenetic corrections, which support convergent evolution. However, substantial differences were observed in the expression profiles of opsin genes in the eyes between Nomorhamphus and Oryzias. Particularly, the expression levels of the long wavelength‐sensitive genes were negatively correlated between the taxa, indicating that they have different visual sensitivities despite living in similar light environments. Thus, the convergence of body colorations between these two freshwater fish taxa was not accompanied by convergence in opsin sensitivities. This system presents a case in which body color convergence can occur between sympatric species via different mechanisms.

No abstract

Halfbeaks (Nomorhamphus sp.) are freshwater fishes that inhabit the Moramo River. Data and scientific information of this species are still limited. This study aims to determine the morphometric characters and growth patterns of halfbeak fish in the Moramo River. This research was conducted from April to June 2020. The fish was caught using a modified seine net. The length of the net is 15 m, width 1.2 m, and mesh size 0.5 x 0.5 inches. There is a pocket in the middle of the net with 40 cm of diameter and 1.5 m of length. The fish were separated by sex, weighed, and preserved using 4% formalin. Measurement of 22 morphometric characters using calipers with an accuracy of 0.1 mm. A total of 120 fish were caught, with 60 males and 60 females. Male fish have body lengths and weights ranging from 40.5-71 mm and 0.45-2.93 g, while female fish have body lengths and weights ranging from 43.5-91.5 mm and 0.5-5.74 g. The results of the growth patterns of male and female halfbeaks are negative allometric (b<3).

No abstract