We used eight microsatellite loci to investigate the mating system in P. unifilis. DNA samples were collected from 66 hatchlings sampled from six nests on a central Amazon River beach near Barreirinha, Amazonas, Brazil. We found that P. unifilis females exhibited a promiscuous mating system (polyandry) with all nests being fathered by at least two males. The presence of multiple males contributing to each clutch was ascertained by the presence of at least two extra alleles in multilocus genotypes in each nest. Our data demonstrate that polyandry seems to be the prevalent system of mating in this endangered species.

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The developmental time of the embryonic stage of Drosophila melanogaster was 21.66% faster and 14.75% slower than controls in populations selected for fast and slow developmental speed, respectively. The genetic model with two main loci with dominant and additive effect added to maternal effect and their relevant interactions can explain 96% of the phenotypic variability in the embryonic developmental time according to 14 crossing progenies involving fast and slow flies.

Landscape features can influence gene flow detected in genetic structure and diversity. The effect will depend on the ability to disperse and may vary between species. Waterfalls and rapids in the Amazon basin have been suggested as causing the diversification and genetic structure of freshwater species, including turtles. Thus, we evaluated the spatial distribution of genetic diversity of Podocnemis unifilis, a widely distributed and endangered turtle, along the main rivers of the Brazilian Amazon. We used the mitochondrial DNA control region to characterize the population structure and test hypotheses of isolation by distance (IBD) or resistance (IBR) through an integrative approach using genetic, geographic, and ecological data. We compared matrices of geographic (linear and in-water distance) and resistance distances (niche modeling and/or waterfalls and rapids) in genetic distance. We found heterogeneous levels of genetic diversity (no spatial patterns) and a geographically complex pattern of population genetic structure. In some localities, gene flow follows watersheds, connecting watercourses, but it also has some genetic structure withing rivers, where waterfalls and rapids act as barriers to dispersal. The IBR better explains the genetic distance, the movement of individuals is influenced by aquatic, vegetational, biological, and geomorphological variables. Efforts for the conservation of the species need to be applied in all its distribution considering landscape genetics. Thus, projects that impact aquatic organisms such as dams and others need to rely on regional or even local migration of Amazonian turtle populations in rivers, verifying the connectivity within each watercourse, improving the knowledge of negative impacts.