The genetic structure of 10 populations of the Merodon aureus group from the Balkan Peninsula was examined through allozyme electrophoresis and mitochondrial DNA sequencing of the cytochrome c oxidase subunit I (COI). Six diagnosable cryptic taxa were identified within the morphologically defined species M. aureus Fabricius, 1805 and M. cinereus (Fabricius, 1794), with clear separation of the populations (((M. aureus A + M. aureus B) + cinereus complex) + M. aureus C). The parsimony analysis of COI sequence data of the aureuscinereus complex using Merodon avidus A species as an outgroup resulted in two main clades, (M. aureus A + M. aureus B) and ((M. aureus C + M. cinereus B + M. cinereus C) + M. cinereus A), which differed on average by 5.7%. The observed spatial distribution of the taxonomic diversity of the group suggested that these taxa originated from a common ancestral population in the Mediterranean. Identification of genetic uniqueness and genetic endemism emphasizes the importance of molecular markers and estimation of genetic diversity in recognition of conservation units. The primary goals of the conservation measures that we propose are the protection of phylogenetic lineages within the highly diverse M. aureus group taxa and conservation of the genetic variation through management of important areas.
Because of its importance as a pollinator and its potential economic usefulness for the biodegradation of organic animal waste, the genetic and phenotypic diversity of the drone fly, Eristalis tenax L. (Diptera: Syrphidae), was studied in both wild and captive populations from southeastern Europe. Wild specimens from a natural protected habitat (with low human impact), field crop habitat (semisynanthropic condition), and intensive pig farming habitat (synanthropic condition) were compared with a laboratory colony reared on artificial media An integrative approach was applied based on allozyme loci, cytochrome c oxidase I mitochondrial DNA, wing traits (size and shape), and abdominal color patterns. Our results indicate that the fourth and eighth generations of the laboratory colony show a severe lack of genetic diversity compared with natural populations. Reduced genetic diversity in subsequent generations (F4 and F8) of the laboratory colony was found to be linked with phenotypic divergence. Loss of genetic variability associated with phenotypic differentiation in laboratory samples suggests a founder effect, followed by stochastic genetic processes and inbreeding. Hence, our results have implications for captive bred Eristalis flies, which have been used in crop pollination and biodegradation of organic waste under synanthropic conditions.
This paper examines molecular and phenotypic variability in the widely spread European hoverfly species complex Merodon avidus. Herein, based on the mitochondrial DNA (mtDNA) sequences of the cytochrome c oxidase subunit I (COI) and morphometric wing parameters, M. avidus is shown to comprise a complex of cryptic species, and one variety is redefined as a valid species: M. bicolor Gil Collado, 1930 (as var. of spinipes). The species M. bicolor, M. avidus A, and M. avidus B were clearly delimited based on their wing size. A total of 29 M. avidus and M. bicolor individuals presented 20 mtDNA haplotypes, four of which were shared by M. avidus A and M. avidus B, three were confined to M. bicolor, seven to M. avidus A, and six to M. avidus B. Sequence divergences between lineages occurring in the Balkan and in Spain ranged from 4.93 to 6.0 (uncorrected p in %) whereas divergences between M. avidus A and M. avidus B were 0.26 to 1.56. Divergence among morphologically identified individuals of M. avidus A and M. avidus B species ranged from 0.13 to 1.58, and from 0.13 to 0.52, respectively. The phenotypic substructuring and observed genetic uniqueness of populations in spatially and temporally fragmented M. avidus taxa were used to identify genetic units. The early split of two allopatric lineages, Spanish M. bicolor and Balkan M. avidus, was followed by diversification in each lineage. Present-day morphological uniformity masks much of the genetic complexity of lineages within the M. avidus complex.
Eristalis tenax L. (Diptera: Syrphidae) is commonly known as the drone fly (adult) or rat-tailed maggot (immature). Both adults and immature stages are identified as potential mechanical vectors of mycobacterial pathogens, and early-stage maggots cause accidental myiasis. We compared four samples from Mount Fruška Gora, Serbia, with the aim of obtaining insights into the temporal variations and sexual dimorphism in the species. This integrative approach was based on allozyme loci, morphometric wing parameters (shape and size) and abdominal colour patterns. Consistent sexual dimorphism was observed, indicating that male specimens had lighter abdomens and smaller and narrower wings than females. The distribution of genetic diversity at polymorphic loci indicated genetic divergence among collection dates. Landmark-based geometric morphometrics revealed, contrary to the lack of divergence in wing size, significant wing shape variation throughout the year. In addition, temporal changes in the frequencies of the abdominal patterns observed are likely to relate to the biology of the species and ecological factors in the locality. Hence, the present study expands our knowledge of the genetic diversity and phenotypic plasticity of E. tenax. The quantification of such variability represents a step towards the evaluation of the adaptive potential of this species of medical and epidemiological importance.
Molecular and phenotypic diversities of Merodon albifrons (Diptera, Syrphidae) of the Aegean islands (Greece) were assessed and compared with the Aegean (Greece) island and island versus mainland sites (Volos, Greece; Alicante, Spain). The complementary use of molecular markers of nuclear and mitochondrial genomes and the study of phenotypic traits (wing size and shape) were found to be powerful tools for revealing hidden temporal (spring versus autumn generation) and spatial (Iberian versus Greek clade, within the Greek clade) diversity within M. albifrons. First, wing size and shape differences discriminated the Spanish M. albifrons clade from the Greek populations, implying the presence of an evolutionarily independent lineage. Wing measurements also revealed hidden temporal (spring versus autumn) phenotypic diversity. By contrast to the mitochondrial cytochrome c oxidase I gene diversity observed in Lesvos (seven haplotypes), Naxos (three haplotypes), and Volos (five haplotypes), only one haplotype was registered in both spring and autumn generations from Chios. The observed allelic and genotypic uniqueness at nuclear allozyme loci indicates temporal (spring versus autumn) and spatial (within and between Chios and Lesvos islands) patterns of genetic diversity. By contrast to the genetic homogeneity found among samples from Chios Island, population structure was found to characterize Lesvos Island. Based on individual relatedness, spatial analysis across islands clustered particular populations of both generations from Lesvos compared to others, which is in agreement with the barriers identified by the software ALLELES IN SPACE.
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