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Genetic differentiation between sandfly populations of Phlebotomus chinensis and Phlebotomus sichuanensis (Diptera: Psychodidae) in China inferred by microsatellites.

Zhang L, Ma Y, Xu J - Parasit Vectors (2013)

Bottom Line: The intra-population genetic diversity, genetic differentiation and effective population size were estimated.Hardy-Weinberg disequilibrium was found in 23 out of 60 (38.33%) comparisons associated with heterozygote deficits, which was likely caused by the presence of allele and the Wahlund effect.The P. chinensis populations did not have a significant divergence from each another.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathogen Biology, Second Military Medical University, Shanghai, China.

ABSTRACT

Background: Phlebotomus chinensis is a primary vector of visceral leishmaniasis; it occurs in various biotopes with a large geographical distribution, ranging from Yangtze River to northeast China. Phlebotomus sichuanensis, a species closely related to P. chinensis in high altitude regions, has a long term disputation on its taxonomic status. Both species occur in the current epidemic regions and are responsible for the transmission of leishmaniasis. Population genetic analysis will help to understand the population structure and infer the relationship for morphologically indistinguishable cryptic species. In this study, microsatellite markers were used for studying the genetic differentiation between P. chinensis and P. sichuanensis.

Methods: Sandflies were collected in 6 representative localities in China in 2005-2009. Ten microsatellite loci were used to estimate population genetic diversity. The intra-population genetic diversity, genetic differentiation and effective population size were estimated.

Results: All 10 microsatellite loci were highly polymorphic across populations, with high allelic richness and heterozygosity. Hardy-Weinberg disequilibrium was found in 23 out of 60 (38.33%) comparisons associated with heterozygote deficits, which was likely caused by the presence of allele and the Wahlund effect. Bayesian clustering analysis revealed three clusters. The cluster I included almost all specimens in the sample SCD collected at high altitude habitats in Sichuan. The other two clusters were shared by the remaining 5 populations, SCJ in Sichuan, GSZ in Gansu, SXL and SXX in Shaanxi and HNS in Henan. The diversity among these 5 populations was low (FST = -0.003-0.090) and no isolation by distance was detected. AMOVA analysis suggested that the variations were largely derived from individuals within populations and among individuals. Consistently, the analysis of ribosomal DNA second internal transcribed spacer (ITS2) sequence uncovered three types of variants, which corresponded with the three gene pools revealed by microsatellites.

Conclusions: The data suggested that the SCD population carried a distinct gene pool, which was differentiated from the other populations. The high altitude ecological habitats, distinctive ITS2 and herein divergence inferred by microsatellite loci support the species status of P. sichuanensis. The P. chinensis populations did not have a significant divergence from each another.

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The UPGMA tree of Phlebotomus sandflies inferred by rDNA-ITS2 sequences. The phylogram was generated using MEGA 5.10. The bootstrap values (1000 replications) are shown on the branch. The sequence id is presented by the Genbank accession numbers followed by the species identity. Population id is indicated next to the clades.
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Figure 4: The UPGMA tree of Phlebotomus sandflies inferred by rDNA-ITS2 sequences. The phylogram was generated using MEGA 5.10. The bootstrap values (1000 replications) are shown on the branch. The sequence id is presented by the Genbank accession numbers followed by the species identity. Population id is indicated next to the clades.

Mentions: The significant deviations from HWE with heterozygote deficiency and the presence of LD suggest the presence of population subdivision within samples (Wahlund effect). We therefore examined if there were different gene pools in these samples. The Bayesian cluster analysis divided specimens into three gene clusters (posterior probability of Bayesian clustering Ln (D) likelihood score optimal for K = 3 clusters) (Figure 2). Sample SCD was clearly distinct from the others; almost all individuals belonged to cluster I (red). The rest of the five samples were mixed with the individuals from the other two gene pools. This pattern was consistent with the pattern inferred from ITS2 sequence comparison [25]. ITS2 sequences of those individuals showed three major types of variants. Based on the alignment of ITS2 sequences (Figure 3), phylogenetic analysis separated those variants into three clades (Figure 4). The SCD collection formed a single clade, the other five collections were clustered into one clade with two sister branches. Interestingly, each of these five collections was mixed with the two major types of ITS variants. In the analysis we also included the ITS2 sequences (PopSet 290794958) available in the NCBI deposited by Gu and Zhang. These specimens were collected in Dongshan, Sichuan; Wen County, Gansu; Sanmenxia, Henan; Yichuan, Shaanxi. Intriguingly, the three major types of ITS2 sequences were found in the collection (Figure 3). The sequence GU385746 was from a specimen collected in Dongshan, Sichuan, where the SCD was sampled in this study. The independent data added a strong support for the presence of distinct genetic clusters in the sandflies.


Genetic differentiation between sandfly populations of Phlebotomus chinensis and Phlebotomus sichuanensis (Diptera: Psychodidae) in China inferred by microsatellites.

Zhang L, Ma Y, Xu J - Parasit Vectors (2013)

The UPGMA tree of Phlebotomus sandflies inferred by rDNA-ITS2 sequences. The phylogram was generated using MEGA 5.10. The bootstrap values (1000 replications) are shown on the branch. The sequence id is presented by the Genbank accession numbers followed by the species identity. Population id is indicated next to the clades.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3649936&req=5

Figure 4: The UPGMA tree of Phlebotomus sandflies inferred by rDNA-ITS2 sequences. The phylogram was generated using MEGA 5.10. The bootstrap values (1000 replications) are shown on the branch. The sequence id is presented by the Genbank accession numbers followed by the species identity. Population id is indicated next to the clades.
Mentions: The significant deviations from HWE with heterozygote deficiency and the presence of LD suggest the presence of population subdivision within samples (Wahlund effect). We therefore examined if there were different gene pools in these samples. The Bayesian cluster analysis divided specimens into three gene clusters (posterior probability of Bayesian clustering Ln (D) likelihood score optimal for K = 3 clusters) (Figure 2). Sample SCD was clearly distinct from the others; almost all individuals belonged to cluster I (red). The rest of the five samples were mixed with the individuals from the other two gene pools. This pattern was consistent with the pattern inferred from ITS2 sequence comparison [25]. ITS2 sequences of those individuals showed three major types of variants. Based on the alignment of ITS2 sequences (Figure 3), phylogenetic analysis separated those variants into three clades (Figure 4). The SCD collection formed a single clade, the other five collections were clustered into one clade with two sister branches. Interestingly, each of these five collections was mixed with the two major types of ITS variants. In the analysis we also included the ITS2 sequences (PopSet 290794958) available in the NCBI deposited by Gu and Zhang. These specimens were collected in Dongshan, Sichuan; Wen County, Gansu; Sanmenxia, Henan; Yichuan, Shaanxi. Intriguingly, the three major types of ITS2 sequences were found in the collection (Figure 3). The sequence GU385746 was from a specimen collected in Dongshan, Sichuan, where the SCD was sampled in this study. The independent data added a strong support for the presence of distinct genetic clusters in the sandflies.

Bottom Line: The intra-population genetic diversity, genetic differentiation and effective population size were estimated.Hardy-Weinberg disequilibrium was found in 23 out of 60 (38.33%) comparisons associated with heterozygote deficits, which was likely caused by the presence of allele and the Wahlund effect.The P. chinensis populations did not have a significant divergence from each another.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pathogen Biology, Second Military Medical University, Shanghai, China.

ABSTRACT

Background: Phlebotomus chinensis is a primary vector of visceral leishmaniasis; it occurs in various biotopes with a large geographical distribution, ranging from Yangtze River to northeast China. Phlebotomus sichuanensis, a species closely related to P. chinensis in high altitude regions, has a long term disputation on its taxonomic status. Both species occur in the current epidemic regions and are responsible for the transmission of leishmaniasis. Population genetic analysis will help to understand the population structure and infer the relationship for morphologically indistinguishable cryptic species. In this study, microsatellite markers were used for studying the genetic differentiation between P. chinensis and P. sichuanensis.

Methods: Sandflies were collected in 6 representative localities in China in 2005-2009. Ten microsatellite loci were used to estimate population genetic diversity. The intra-population genetic diversity, genetic differentiation and effective population size were estimated.

Results: All 10 microsatellite loci were highly polymorphic across populations, with high allelic richness and heterozygosity. Hardy-Weinberg disequilibrium was found in 23 out of 60 (38.33%) comparisons associated with heterozygote deficits, which was likely caused by the presence of allele and the Wahlund effect. Bayesian clustering analysis revealed three clusters. The cluster I included almost all specimens in the sample SCD collected at high altitude habitats in Sichuan. The other two clusters were shared by the remaining 5 populations, SCJ in Sichuan, GSZ in Gansu, SXL and SXX in Shaanxi and HNS in Henan. The diversity among these 5 populations was low (FST = -0.003-0.090) and no isolation by distance was detected. AMOVA analysis suggested that the variations were largely derived from individuals within populations and among individuals. Consistently, the analysis of ribosomal DNA second internal transcribed spacer (ITS2) sequence uncovered three types of variants, which corresponded with the three gene pools revealed by microsatellites.

Conclusions: The data suggested that the SCD population carried a distinct gene pool, which was differentiated from the other populations. The high altitude ecological habitats, distinctive ITS2 and herein divergence inferred by microsatellite loci support the species status of P. sichuanensis. The P. chinensis populations did not have a significant divergence from each another.

Show MeSH
Related in: MedlinePlus