Landscape genetics and wing morphometrics show a lack of structuring across island and coastal populations of the drone fly in theMediterranean

Abstract

The Mediterranean basin is a region of species richness, rarity and endemism, and is thus an area of significant conservation importance. Conservation of insect biodiversity benefits pollination services in the fragmented Mediterranean landscape. However, the question of the distribution patterns of an important longdistance pollen disperser, the hoverfly Eristalis tenax (Diptera, Syrphidae), remains open. Therefore, we explored the spatial distribution of genetic and phenotypic diversity of this species across the Central-Eastern Mediterranean. Connectivity between continental and island populations of E. tenax was studied by integrating molecular (allozyme loci and mitochondrial DNA sequences of the cytochrome c oxidase subunit I gene) and phenotypic data (wing geometric morphometrics). Allozyme (FST values, STRUCTURE analysis, analysis of molecular variance) and phenotypic data (wing shape) and landscape genetics (Alleles in Space analysis) suggest that E. tenax populations within the Mediterranean are largely connected, and that there is an absence of large-scale geographic structuring. Intraspecific variability was only 1.54% among samples, and the Mediterranean populations showed an almost complete lack of COI mtDNA haplotype diversity. Thus, our results suggest that E. tenax populations are well mixed, and that a considerable amount of gene flow takes place, even among populations that are a great distance apart. As E. tenax's ecological amplitude is wide, and the species is therefore widespread in both natural and man-made landscapes, it probably maintains a high level of population similarity by its large population sizes (as revealed by the θ parameter) and constant intermixing among populations. From an applied point of view, large-scale species intermixing enables pollen spread across distant island plant populations, especially those threatened by extinction. Potts & Packer, 2005;Potts et al., 2006).The diversity of flower-visiting insects (e.g. Steffan-Dewenter et al., 2002) may be influenced by landscape context and habitat quality. For instance, Meyer, Jauker & Steffan-Dewenter (2009) found contrasting resource-dependent responses of hoverfly richness and density to landscape structure. Hence, landscape structure can be expected to affect the number, size, quality and distance of flower patches available for insect visitors. Although it seems certain that pollinators may bring pollen to relatively distant isolates, providing infusions of new genetic variability in plant populations (e.g. Richards, 2000), much more studies are needed as we bs_bs_banner Journal of Zoology Journal of Zoology. Print ISSN 0952-8369 L. Francuski et al. Landscape genetics and wing morphometrics of the drone fly Journal of Zoology 292 (2014) 156-169

Assessing spatial population structure and heterogeneity in the dronefly

“…We obtained individual genotypes from subsets of individuals used in previous studies: Francuski et al . (2011; 2013 a,b ; 2014 a,b ). Sample sizes in populations ranged from 11 to 122 individuals while distance between sampling sites ranged from 17 to 3322 km.…”

“…Up to date, two studies were brought to bear on questions of E. tenax widerange movement and gave contrasting results. Using genetic (allozymes and mitochondrial DNA sequences of the cytochrome c oxidase subunit I gene) and phenotypic data (wing shape), our previous study suggested that E. tenax populations in the Central-Eastern Mediterranean are largely connected and that there is an absence of geographic structuring across island and coastal populations (Francuski et al, 2014b). On the other hand, application of landscape genetics revealed a subtle but significant subdivision between Balkan populations and populations from Central and Northern Europe of the taxon despite the continuous between-population exchange of individuals across the European landmass (Francuski et al, 2013a).…”

Sexual size and shape dimorphism, and allometric scaling in the pupal and adult traits of Eristalis tenax

“…Such consistent allometric patterns, accompanied with the conserved pattern of SShD (e.g. Francuski et al, 2011; Francuski, Djurakic, Ludoški, et al, 2014; Francuski, Djurakic, Ståhls, & Milankov, 2014; Ludoški et al, 2008; Milankov et al, 2010a, 2010b, 2013), might be developmentally (Bolstad et al, 2015; Reis et al, 2021) and/or evolutionarily constrained, suggesting species‐specific adaptations and plastic responses. For instance, the percentage of wing shape variation explained by allometry was found to range from 34% ( Drosophila melanogaster ) to 16% ( Ceratitis capitata ) and 13% ( Musca domestica ), which was congruent with species‐specific scaling relationships (Reis et al, 2021).…”

“…Contrary to this, deeper insights into spatial pattern of genetic and phenotypic variation on the local and regional scale were provided. Indeed, landscape genetic studies suggested that populations of this highly migratory species were largely connected (Francuski, Djurakic, et al, 2013; Francuski, Djurakic, Ståhls, & Milankov, 2014; Francuski, Ludoški, & Milankov, 2013; Francuski & Milankov, 2015).…”

Investigating population differentiation in a major African agricultural pest: evidence from geometric morphometrics and connectivity suggests high invasion potential

“…To address these important knowledge gaps, in this study, we generated both molecular and morphological data for the same individuals, resulting in two parallel but independent data sets. Surprisingly, few studies have adopted this approach despite the clear potential value thereof (but see Bouyer et al 2007;Francoy et al 2009;Bomfim et al 2011;Krosch et al 2013;Francuski et al 2014;Schutze et al 2015a,b).…”