Diatraea saccharalis (Fabricius) is one of the major Lepidopteran pests throughout the Western Hemisphere. In Argentina, it causes significant losses mainly in sugarcane and corn. Previous studies determined the existence of reproductive incompatibilities between populations from Buenos Aires and Tucumán from different host plants; however, the genetic base of this incompatibility is still unknown. The aim of this study was to determine the existence of genetic structure of D. saccharalis populations collected from different hosts and regions in Argentina, comparing with those from Brazil, through COI and NGS. The COI analyzes showed a haplotypic diversity of 0.8 and a Nucleotide diversity of 0.0058. AMOVA revealed a greater variation within populations than among them. The 17 haplotypes detected were linked in a single parsimony network that did not reveal clusters clearly influenced by geographic locations or the host plants from which populations were collected. A total of 4.549 SNPs were obtained through NGS. Out of the 2,349 outlier loci, 84 showed similarities with known proteins previously characterized. The coefficient of inbreeding showed that the mating among the populations, although it is being random, presents the same degree of selection. The FST values showed a high variation among Argentina and Brazil populations; however, did not show a clearly defined trend of the influence of the host and/or the distance. In the DAPC, three different groups were formed, a group that includes the samplings from Brazil and two groups from Argentina. Results indicated the existence of genetic divergence in D. saccharalis populations.

Dispersal is a crucial mechanism to living beings, allowing them to reach new resources such that populations and species can explore new environments. However, directly observing the dispersal mechanisms of widespread species can be costly or even impracticable, which is the case for mangrove trees. The influence of ocean currents on the mangroves’ propagules’ movement has been increasingly evident; however, few studies mechanistically relate the patterns of population distribution with the dispersal by oceanic currents under an integrated framework. Here, we evaluate the role of oceanic currents on dispersal and connectivity of Rhizophora mangle along the Southwest Atlantic. We inferred population genetic structure and migration rates based on single nucleotide polymorphisms, simulated the displacement of propagules along the region and tested our hypotheses with Mantel tests and redundancy analysis. We observed a two populations structure, north and south, which is corroborated by other studies with Rhizophora and other coastal plants. The inferred recent migration rates do not indicate gene flow between the sampled sites. Conversely, long-term migration rates were low across groups and contrasting dispersal patterns within each one, which is consistent with long-distance dispersal events. Our hypothesis tests suggests that both isolation by distance and isolation by oceanography (derived from the oceanic currents) can explain the neutral genetic variation of R. mangle in the region. Our findings expand current knowledge of mangrove connectivity and highlight how the association of molecular methods with oceanographic simulations improve the interpretation power of the dispersal process, which has ecological and evolutionary implications.

To the Neotropical genus Acrocomia (Arecaceae) is attributed eight species with a wide distribution in America. A. aculeata and A. totai are the most important species because of their high economic potential for oil production. However, there is no consensus in their classification as different taxons and their distinctiveness is particularly challenging due to morphological similarities with large plasticity of the traits. In addition, there is doubt about the occurrence of interspecific hybrids between both species. In this study, we applied a genetic population approach to assessing the genetic boundaries, diversity and to identify interspecific hybrids of A. aculeata and A. totai. Thirteen loci of simple sequence repeat (SSR) were employed to analyze twelve populations representing a wide distribution of species, from Minas Gerais, Brazil to Formosa, Argentina. Based on the Bayesian analysis (STRUCTURE and NewHybrids) and Discriminant Analysis of Principal Components (DAPC), our study supports the recognition of A. aculeata and A. totai as two species and the estimates of genetic parameters revealed more genetic diversity in A. totai (HE=0.551) than in A. aculeata (HE=0.466). We obtained evidence of hybridization between the species and that admixed individuals were assigned as F2 hybrids. In conclusion, this study showed the usefulness of microsatellite markers to elucidate the genetic boundaries of A. aculeata and A. totai, supporting their classification as different species and increase our knowledge about genetic diversity at the level of populations and species. The results are essentials to establish strategies for the adequate management, conservation, and domestication of both species.