Project description:The fish order Syngnathiformes has been referred to as a collection of misfit fishes, comprising commercially important fish such as red mullets as well as the highly diverse seahorses, pipefishes, and seadragons-the well-known family Syngnathidae, with their unique adaptations including male pregnancy. Another ornate member of this order is the species mandarinfish. No less than two types of chromatophores have been discovered in the spectacularly colored mandarinfish: the cyanophore (producing blue color) and the dichromatic cyano-erythrophore (producing blue and red). The phylogenetic position of mandarinfish in Syngnathiformes, and their promise of additional genetic discoveries beyond the chromatophores, made mandarinfish an appealing target for whole-genome sequencing. We used linked sequences to create synthetic long reads, producing a highly contiguous genome assembly for the mandarinfish. The genome assembly comprises 483 Mbp (longest scaffold 29 Mbp), has an N50 of 12 Mbp, and an L50 of 14 scaffolds. The assembly completeness is also high, with 92.6% complete, 4.4% fragmented, and 2.9% missing out of 4584 BUSCO genes found in ray-finned fishes. Outside the family Syngnathidae, the mandarinfish represents one of the most contiguous syngnathiform genome assemblies to date. The mandarinfish genomic resource will likely serve as a high-quality outgroup to syngnathid fish, and furthermore for research on the genomic underpinnings of the evolution of novel pigmentation.
Project description:The complete mitogenome sequence of the ruby dragonet Synchiropus sycorax was first determined using next-generation sequencing strategy in this study. The circle genome was 16,656 bp in length and consisted of 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and 1 control region. The mitochondrial gene arrangement of S. sycorax is similar to those of most other fish species. Results from neighbor-joining phylogenetic analysis showed that S. sycorax clustered with S. splendidus and other species of the family Callionymidae. This study will be valuable for phylogenetic analysis of the genus Synchiropus and the other genera of the order Syngnathiformes.
Project description:The mandarinfish Synchiropus splendidus is extensively collected in Southeast Asia (mainly in the Philippines) and highly favoured for the marine aquarium trade. Males are more popular than females for their large first dorsal fins and the fishery is not managed. To examine possible population replenishment dynamics arising as a result of selective fishing, the effects of sex-selective fishing on sex ratios and population connectivity were considered. This study determined the sex ratios and analyzed the population genetic structure from mandarinfish collected at six locations: one from Palau, where the species is not exploited, and five from Bohol in the Philippines, where the species has long been heavily fished. The findings reported very low male to female ratios (0.12 to 0.30) from four of the five locations in Bohol, with relatively more males to females in the specimens collected from Palau (2.3). The analyses from allozymes (43 alleles from 10 loci) and microsatellites (118 alleles from 5 loci) revealed that genetic connectivity was high among the five locations in the Philippines as well as with the specimens collected from the more-distant Palau. The genetic homogeneity observed across the geographical range considered is inconsistent with the hypothesized limited dispersal ability of the species and could be explained by recent species range expansion associated with sea level rise in the region. The results suggest that the present genetic structure, at least in the geographic region considered, may not be determined by current patterns of gene flow, but may, instead, be driven by recent sea-level changes associated with periods of glaciation. Caution is suggested to ensure that heavily localized fishing does not produce excessively biased adult sex ratios.
