Genetic dynamics in the sand fly (Diptera: Psychodidae) nuclear and mitochondrial genotypes: evidence for vector adaptation at the border of Iran with Iraq.

Sahar Ebrahimi,Ali Bordbar,Parviz Parvizi

doi:10.1186/s13071-016-1603-5

Abstract

BackgroundOur investigation uses nucleotide variations of the genera Phlebotomus and Sergentomyia using the EF-1α and Cyt b genotype regions to describe the sand fly fauna and genetic aspects collected at war-torn sites of the Khuzestan boundary between Iraq and Iran.MethodsAll sand fly species were characterized using molecular genetics. The field work was conducted in six districts including 24 locations in remote areas for three years at the peak of sand fly activity during cutaneous leishmaniasis (CL) transmission seasons. The distribution of CL vectors was determined based on the climatic regionalization using the kriging method in ArcGIS model. DNA of sand fly pools were screened via polymerase chain reaction (PCR) using neutrality (Tajima’s D) and neutral allele frequency (Fu’s Fs) tests to measure the effect of randomly evolving DNA sequence on the genetic diversity of sand fly populations in response to habitat fragmentation and landscape modification.ResultsAmong the 1213 specimens, ten species were identified based on morphology. The non-native species Phlebotomus sergenti was unequivocally found for the first time in the studied regions. Nucleotide substitutions of sand fly sequences varied most in the most disrupted districts (Dashte-Azadegan and Abadan; disparity index test: P < 0.05). The haplotypes of Cyt b from the subgenus Sergentomyia and P. papatasi revealed more heterogeneity (Tajima’s D > +2) than P. alexandri (D > +1), which suggests widespread heteroplasmic mitochondrial DNA mutations in the same mtDNA gene among different sand fly species. Subgenus Sintonius exhibited greater fitness (D = 0) and (neutrality test; P > 0.05) no evidence of selection. The sequence of the nuclear gene EF-1α indicated similar nucleotide differences, as observed for the Cyt b gene, in all sand fly species, but lower levels of polymorphisms (D > +1) were observed compared with the mitochondrial Cyt b gene (D > +2) in the subgenus Sergentomyia.ConclusionOur findings describe random nucleotide diversity in the Phlebotomus and Sergentomyia population gene pools due to recent anthropogenic influence. A phylogenetic analysis showed that the closely related species are positioned in monophyletic clades, except for the subgenus Sergentomyia and P. sergenti, and highlights the importance of haplotype variations for the development of adaptability.

Highlights

Our investigation uses nucleotide variations of the genera Phlebotomus and Sergentomyia using the elongation factor-1α (EF-1α) and Cytochrome b (Cyt b) genotype regions to describe the sand fly fauna and genetic aspects collected at war-torn sites of the Khuzestan boundary between Iraq and Iran
In a noteworthy Zoonotic Cutaneous Leishmaniasis (ZCL) focus, in a tropical climate region in southwestern Iran, Khuzestan Province has suffered from the Iraq-Iran war and has recently been involved in Daesh terrorist destruction, which has led to ecological instability in the region, providing adequate conditions for flourishing heterogeneity and allowing for great diversity among sand fly species
Morphological identification and sequenced specimens For this investigation, we identified ten species among Phlebotomus and Sergentomyia sand flies caught in 23 villages and a riverside next to the Khuzestan boundaries (Table 1)

Summary

Introduction

Our investigation uses nucleotide variations of the genera Phlebotomus and Sergentomyia using the EF-1α and Cyt b genotype regions to describe the sand fly fauna and genetic aspects collected at war-torn sites of the Khuzestan boundary between Iraq and Iran. Despite the large and diverse sand fly distribution range in the geographical borders of the Khuzestan Province between Iran and Iraq, the sand fly species and the population structure of CL sand flies are not well-known. Simultaneous utilization of the sequence of applying both mitochondrial Cytochrome b (Cyt b) and conserved nuclear marker elongation factor-1α (EF-1α) as proper DNA markers have already provided data for analyzing the phylogenetic relationship among sand fly species [9]. These genes provide sufficient information to discern the species’ ancestor population in the natural habitat of phlebotomine sand flies [10]

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