Flatfishes colonised freshwater environments by acquisition of various DHA biosynthetic pathways.

The colonisation of freshwater environments by marine fishes has historically been considered a result of adaptation to low osmolality. However, most marine fishes cannot synthesise the physiologically indispensable fatty acid, docosahexaenoic acid (DHA), due to incomplete DHA biosynthetic pathways, which must be adapted to survive in freshwater environments where DHA is poor relative to marine environments. By analysing DHA biosynthetic pathways of one marine and three freshwater-dependent species from the flatfish family Achiridae, we revealed that functions of fatty acid metabolising enzymes have uniquely and independently evolved by multi-functionalisation or neofunctionalisation in each freshwater species, such that every functional combination of the enzymes has converged to generate complete and functional DHA biosynthetic pathways.

Phenotypic/genotypic sex mismatches and temperature-dependent sex determination in a wild population of an Old World atherinid, the cobaltcap silverside Hypoatherina tsurugae.

Several New World atheriniforms have been recognized as temperature-dependent sex determined (TSD) and yet possess a genotypic sex determinant (amhy) which is primarily functional at mid-range temperatures. In contrast, little is known about the sex determination in Old World atheriniforms, even though such knowledge is crucial to understand the evolution of sex determination mechanisms in fishes and to model the effects of global warming and climate change on their populations. This study examined the effects of water temperature on sex determination of an Old World atheriniform, the cobaltcap silverside Hypoatherina tsurugae, in which we recently described an amhy homologue.

The Duplicated Y-specific Gene Is Conserved and Linked to Maleness in Silversides of the Genus .

Sex-determining genes have been successively isolated in several teleosts. In and , the gene has been identified as a master sex-determining gene. However, whether this gene is conserved along related species is still unknown.

A Duplicated, Truncated Gene Is Involved in Male Sex Determination in an Old World Silverside.

A master sex-determining gene, the Y chromosome-linked anti-Müllerian hormone () gene, has been described in two New World atheriniform species but little is known on the distribution, evolution, and function(s) of this gene in other Atheriniformes. Interestingly, has been found to coexist with temperature-dependent sex determination (TSD), providing a unique opportunity to explore the interplay between genotypic and environmental sex determination. In this study, the search for an homolog was extended to an Old World atheriniform, the cobaltcap silverside (Atherinidae).