Dr. Waldir Berbel-Filho

Aim: The disjunct distributions of freshwater organisms along coastal drainages are usually explained by paleodrainages formed during sea-level retreats that connected currently isolated basins, or by river capture from tectonic adjustments between adjoining watersheds. We evaluate the relative importance of these events on the genetic variation of freshwater fishes inhabiting the Serra do Mar in eastern Brazil, a region with steep mountains and pronounced bays.
Location: Coastal river drainages in southeastern Brazil. Taxon: Catfishes of the Trichomycterus alternatus group. Methods: We tested the effects of paleolandscape connections (GIS-reconstructed paleodrainages and putative river captures) on the genetic structure (mitochondrial and nuclear markers) of T. alternatus from 15 drainages using phylogenetic reconstructions, lineage delimitation methods and analyses of molecular variance.
Results: Trichomycterus alternatus is monophyletic and comprised of three main lineages: two restricted to the basin at its northernmost distribution and another broadly distributed to the south. In the latter, seven major cytb clades were geographically compatible with the eight paleodrainages, with three
incongruences matching river captures previously described for the Guanabara Bay (GB). Shared haplotypes among isolated rivers flowing into GB provide the first molecular evidence of the ‘Rio de Janeiro’ paleoriver.
Main conclusions: Dispersal via paleorivers is an important process, but it is not enough to recover the most recent dispersive events. Therefore, integrating both paleo-riverine configuration (GIS-based) and localized river captures (geological studies) is crucial to reveal the role of past geological and climatic events on the distribution of freshwater organisms. Taken together, these two factors significantly explained a high portion T. alternatus genetic structure along coastal drainages, revealing a paleolandscape scenario that may have been used by other freshwater Atlantic Forest taxa.

Parental effects influence offspring phenotypes through pre- and post-natal routes but little is known about their molecular basis, and therefore their adaptive significance. Epigenetic modifications, which control gene expression without changes in the DNA sequence and are influenced by the environment, may contribute to parental effects. We investigated the effects of environmental enrichment on the behaviour, metabolic rate and brain DNA methylation patterns of parents and offspring of the highly inbreed mangrove killifish (Kryptolebias marmoratus). Parental fish reared in enriched environments had lower cortisol levels, lower metabolic rates and were more active and neophobic than those reared in barren environments. They also differed in 1,854 methylated cytosines (DMCs). Offspring activity and neophobia were determined by the parental environment. Among the DMCs of the parents, 98 followed the same methylation patterns in the offspring, three of which were significantly influenced by parental environments irrespective of their own rearing environment. Our results suggest that parental environment influences the behaviour and, to some extent, the brain DNA methylation patterns of the offspring.