Sexually selected sexual selection: Can evolutionary retribution explain female ornamental colour?

Complete mitochondrial genome of a livebearing freshwater fish (Cyprinodontiformes: Poeciliidae): Poecilia parae

Members of the fish family Poeciliidae (livebearing 'tooth-carps') have historically been used as models in medical research, behavior ecology, and biological control. This group of primarily freshwater fishes is highly tolerant to environmental factors such as salinity and warm temperatures and includes some invasive species. Here, we present the mitochondrial genome of Poecilia parae. A representative of this species was obtained from Suriname. The complete mitochondrial genome was sequenced using Oxford Nanopore technology and is 16,559 bp long. The genome contains 13 protein-coding genes, two ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs), and one control region (D-loop). Phylogenetic analysis yielded topologies similar to those previously published. The data generated here will be useful in future studies of comparative biology and those utilizing environmental DNA (eDNA).

Genome biology of the Darkedged Splitfin, Girardinichthys multiradiatus, and the evolution of sex chromosomes and placentation

Viviparity evolved independently about 150 times in vertebrates and more than 20 times in fish. Several lineages added to the protection of the embryo inside the body of the mother, the provisioning of nutrients, and physiological exchange. This often led to the evolution of a placenta. Among fish, one of the most complex systems serving the function of the placenta is the embryonal trophotaenia/ovarian luminal epithelium of the goodeid fishes. For a better understanding of this feature and others of this group of fishes, high-quality genomic resources are essential. We have sequenced the genome of the darkedged splitfin, Girardinichthys multiradiatus. The assembly is chromosome level and includes the X and Y Chromosomes. A large male-specific region on the Y was identified covering 80% of Chromosome 20, allowing some first inferences on the recent origin and a candidate male sex determining gene. Genome-wide transcriptomics uncovered sex-specific differences in brain gene expression with an enrichment for neurosteroidogenesis and testis genes in males. The expression signatures of the splitfin embryonal and maternal placenta showed overlap with homologous tissues including human placenta, the ovarian follicle epithelium of matrotrophic poeciliid fish species and the brood pouch epithelium of the seahorse. Our comparative analyses on the evolution of embryonal and maternal placenta indicate that the evolutionary novelty of maternal provisioning development repeatedly made use of genes that already had the same function in other tissues. In this way, preexisting modules are assembled and repurposed to provide the molecular changes for this novel trait.