Biology subjects

Masengi, K. W. A.

Publications and source records attributed to Masengi, K. W. A..

2 recordsLinked to original sources

bioRxiv2022

Diversity of sex chromosomes in Sulawesian medaka fishes

Recent genetic and genomic studies have revealed tremendous diversity in sex chromosomes across diverse taxa. Although theoretical studies predict that sex chromosome evolution can drive the evolution of sexual dimorphism, empirical studies are still limited. A taxonomic group that shows diversity in both sex chromosomes and sexual dimorphism provides excellent opportunity to investigate the link between the evolution of sex chromosomes and sexual dimorphism. The medaka fishes (family Adrianichthyidae) exhibit both rapid sex chromosome turnovers and diversification of sexually dimorphic traits. In the present study, we investigated the sex chromosomes of 13 Oryzias species from Sulawesi, Indonesia, that have diversified in sexual dichromatism. Using pooled sequencing we found sex chromosomes in 9 species that all had XY systems, with a few species being possibly modified by multiple loci. Seven species (O. woworae, O. asinua, O. wolasi, O. matanensis, O. celebensis, O. hadiatyae, and O. dopingdopingensis) share linkage group (LG) 24 as sex chromosomes; however, they differed in the length and magnitude of sequence divergence between the X and Y chromosomes. The sex chromosome of O. eversi was LG4, which has not been reported as a sex chromosome in any other medaka species. In O. sarasinorum, LG16 and LG22 are associated with sex. Although LG16 was found to be sex-linked in another medaka species previously examined, the sex-determining regions did not overlap. Frequent turnovers and the great diversity of the sex chromosomes make Sulawesian medaka species a model system for investigating the roles of sex chromosome evolution in the diversification of sexual dimorphism.

evolutionary biology↗

bioRxiv2020

Mitochondrial introgression by ancient admixture between two distant lacustrine fishes in Sulawesi Island

Sulawesi, an island located in a biogeographical transition zone between Indomalaya and Australasia, is famous for its high levels of endemism. Ricefishes (family Adrianichthyidae) are an example of taxa that have uniquely diversified on this island. It was demonstrated that habitat fragmentation due to the Pliocene juxtaposition among tectonic subdivisions of this island was the primary factor that promoted their divergence; however, it is also equally probable that habitat fusions and resultant admixtures between phylogenetically distant species may have frequently occurred. Previous studies revealed that some individuals of Oryzias sarasinorum endemic to a tectonic lake in central Sulawesi have mitochondrial haplotypes that are similar to the haplotypes of O. eversi, which is a phylogenetically related but geologically distant (ca. 190 km apart) adrianichthyid endemic to a small lake. In this study, we tested if this reflects ancient admixture of O. eversi and O. sarasinorum. Population genomic analyses of genome-wide single-nucleotide polymorphisms revealed that O. eversi and O. sarasinorum are substantially reproductively isolated from each other. Comparison of demographic models revealed that the models assuming ancient admixture from O. eversi to O. sarasinorum was more supported than the models assuming no admixture; this supported the idea that the O. eversi-like mitochondrial haplotype in O. sarasinorum was introgressed from O. eversi. This study is the first to demonstrate ancient admixture of lacustrine organisms in Sulawesi beyond 100 km. The complex geological history of this island enabled such island-wide admixture of lacustrine organisms, which usually experience limited migration.

evolutionary biology↗