# Molecular Population Genetics of Aspen Mosaic-Associated Virus in Finland and Sweden
## 4 Conclusions
The nucleotide diversity of blackberry leaf mottle-associated virus (BLMaV) was rather low when compared to FMV and European mountain ash ringspot-associated virus (EMAReV) [31]. Therefore, it could be concluded that the genomes of emaraviruses including AsMaV are relatively conserved. The AsMaV isolates sequenced in this study were separated based on their geographical origin based on the phylogenetic trees. Deviations from the neutral equilibrium model for the three analyzed genes together with a combination of high haplotype diversity, overall low nucleotide diversity within Finnish and Swedish isolates, and negative values of [PERSON]'s and Fu and Li's value indicate the existence of population expansions for AsMaV which is expected following genetic drift, which accompanies bottleneck transmission [74]. Evolutionary bottlenecks/founder effects may arise as a result of plant- or vector-associated effects [75]. Root suckering will generally occur in the aspen stands as they deteriorate or as they are disturbed by fire or other events. In addition, some species of gall mites have been identified as a natural vector for a few emaraviruses and for most emaraviruses such a natural vector has not been identified so far [6]. Occurrence of population expansions following a bottleneck event for other multi-segmented plant RNA virus have been reported [76], and suggest that the inferred differentiation between viral populations is because of demographically related events. The Finnish and Swedish AsMaV isolates sequenced in this study displayed geographical structuring that may have arisen by founder effects. The purifying selection acts on low to moderate genetic diversity of AsMaV isolates to preserve function of the protein. Since emaraviruses have a narrow host range and, in most of reported emaraviruses, they have been reported only from one natural host, it might reduce some factors affecting the shape of the population in comparison with viruses with a wider host range. Only a few reports are available for natural vectors of emaraviruses. The reported mites have also a narrow host range which could subsequently cause the lower genetic diversity of the emaraviruses. In this context, the most diversity in AsMaV isolates was found in Kuninkaansaari and Vallisari islands. There is a need for investigation of the mite species found on _Populous_ spp. and their potential in transmissions of AsMaV. Distant isolates of AsMaV showed some changes in aa sequences in comparison to other isolates and bioinformatic data predicted a post-translational Mucin-type O-glycosylation site in GPP which could happen because of interactions with the natural vector. Further studies are needed to investigate whether the mutations identified in the sequence variants of AsMaV RNA1, RNA3, and RNA4 affect the virus replication cycle, the severity of symptoms expressed by virus, may contribute to the decline in trees, or have an impact on the interaction with the assumed mite vectors of the virus. The functional characterization of the AsMaV-host-vector relationships will contribute to our understanding of the ecological position of the virus, and are a prerequisite to handle and prevent the damages including the decline that may be caused by the virus, especially when considering additional stress factors such as the predisposition and impacts of climate change. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/v15081678/s1](https://www.mdpi.com/article/10.3390/v15081678/s1)]([https://www.mdpi.com/article/10.3390/v15081678/s1](https://www.mdpi.com/article/10.3390/v15081678/s1)), Table S1: list of collected samples; Table S2: characteristics of the oligonucleotides used in this study; Table S3: (a) the GenBank accession numbers of the isolates sequenced in this study; (b) the GenBank Accession numbers for the complete genome. Figure S1: distribution of Aanl restrictotypes of AsMaV-RNA3 on a geographical map. **Author Contributions:** Conceptualization, S.N.Z.