Efeito de hospedeiros na variabilidade de caracteres morfológicos e marcadores epigenéticos em Moscas-das-frutas Anastrepha fraterculus (DIPTERA; TEPHRITIDAE)

Abstract

In the genus Anastrepha (Diptera: Tephritidae) of fruit flies, the fraterculus group stands out for having highly generalist species specialized in different fruits, being one of the most economically important for national and global agriculture. In general, such species are differentiated through morphological characters, however the limits of this differentiation are difficult to determine for some taxa, especially in the fraterculus species group, which presents inclusive cryptic species. This happens in some cases due to the recent separation between species, but also due to overlapping of character measurements . This phenotypic variation may even occur through the action of epigenetic factors, since these changes may be related to environmental stimuli that trigger rapid responses. This work aimed to investigate the effect of hosts fruits on populations of Anastrepha fraterculus, identifying phenotypic variations in several morphological characters present in the head, thorax, aculeus and wing, as well as investigating the presence of epigenetic marks, such as DNA methylation, between specimens that emerged from different fruits. For this purpose, flies derived from the ecosystem were used, collected from five different hosts (cherry do rio grande, pitanga, uvaia, guava and guabiroba) around the Federal University of São Carlos – São Carlos campus. Morphometric analyzes were carried out on 117 samples from the 5 fruits found, with 18 morphological characters being analyzed using the multivariate statistical method, such as principal component analysis (PCA), discriminant analysis (DFA) and Mahalanobis distance (MD). Epigenetic analyzes were investigated in a subset of these flies, using data obtained through sequencing on a MinION equipment from Oxford Nanopore Technologies of two pools of heads per fruit, which allows the study of 5mC and 6mA DNA methylation. Methylation calling at 6mA sites between flies that emerged from different fruits was done using the mCaller software and its variation between samples (DMRs) investigated by a non-parametric analysis. In turn, an analysis of differentially methylated 5mC regions (DMRs) was performed using the pycoMeth pipeline, the results of which were investigated for enrichment of gene ontological categories (GO). The morphometric results indicated phenotypic variability in morphological characters of flies from five different fruits enough to separate the vast majority of samples emerging from different fruits. Epigenetic analyzes allowed recording for the first time the presence of DNA methylation in fruit flies A. fraterculus at both cytosines (5mC) and adenines (6mA). The investigation into the distribution of these DMRs suggested important genes in the process of differentiating this species into different fruits, as well as several enriched classes of genes responsible for different functions in biological processes, including the morphogenesis of anatomical structures and the development of the nervous system. These results provide a basis for future investigations into epigenetic modifications and phenotypic variability in fruit flies, highlighting their relevance in the regulation of phenotypes, host influence and choice, and evolutionary adaptation. Understanding these adaptation patterns is crucial not only for taxonomy, but also for elucidating the evolutionary processes, and ecological dynamics, involved in the interactions between flies and their hosts.