Genetic and growth differences in the outcrossings between two clonal strains of the self-fertilizing mangrove killifish

The populations of the only known self-fertilizing vertebrate Kryptolebias marmoratus (Poey, 1880) (formerly known as Rivulus marmoratus Poey, 1880; Cyprinodontiformes: Aplocheilidae) usually consist of different homozygous lineages; however, heterozygous individuals are found occasionally and ratios of homozygosity and heterozygosity in populations are dependent on the proportion of males. However, it is still unclear what impact male-mediated genetic diversity has on the phenotype of K. marmoratus. To clarify this, we attempted outcrossing between male and hermaphrodite of two different clonal strains with different life-history traits using artificial insemination, and examined the genotypes and growth of the hybrid F2 generation. We detected genetic differences between the two clonal strains using amplified fragment length polymorphism (AFLP) analysis with 3 primer combinations, and then obtained 11 AFLP markers. From a total of 31 artificial inseminations with two clonal strains, 1 of 13 hatched fish clearly indicated heterozygosity. The hybrid F2 generations were also heterozygous. Moreover, the growths of the hybrid F2 generation were intermediate of the parental strains from days 0 to 30. Therefore, outcrossing changes genetic architecture and the new genotypes potentially result in new phenotypes of the subsequent generations of K. marmoratus. It may also play a role in adaptation to new environments and the facilitation of local adaptation

Fluviphylax palikur : a new Poeciliid from the Rio Oiapoque basin, northern Brazil (Cyprinodontiformes : Cyprinodoidei), with comments on miniaturization in Fluviphylax and other neotropical freshwater fishes

International audienceFluviphylax palikur, new species, is described from the rio Taparabu, rio Oiapoque basin, northern Brazil. It differs from all other species of the genus by the possession of numerous anal fin rays and vertebrae and by the shape of fourth and fifth ceratobranchials and second pharyngobranchial. Five synapomorphies shared by all species of Fluviphylax except F. palikur, in addition to characters supporting Fluviphylax monophyly, support a hypothesis of a sister-group relationship between the new species and a clade consisting of the remaining species of the genus. Miniaturization and reductive morphological conditions in Fluviphylax are discussed in a phylogenetic context. Miniaturization in Fluviphylax is hypothesized to correspond to a single event, with reductive conditions originating at the base of the Fluviphylax clade and in different intrageneric lineages. A list of Neotropical miniature freshwater fish described in the last 10 years is presented