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Lack of population genetic structure and host specificity in the bat fly, Cyclopodia horsfieldi, across species of Pteropus bats in Southeast Asia.

Olival KJ, Dick CW, Simmons NB, Morales JC, Melnick DJ, Dittmar K, Perkins SL, Daszak P, Desalle R - Parasit Vectors (2013)

Bottom Line: AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations.We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact.Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.

View Article: PubMed Central - HTML - PubMed

Affiliation: EcoHealth Alliance, New York, NY 10001, USA. olival@ecohealthalliance.org

ABSTRACT

Background: Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date.

Methods: We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities.

Results: All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure.

Conclusions: The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of bat flies between the three Pteropus species in the region. We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact. These approaches may have wide implications for understanding zoonotic, epizootic, and enzootic disease dynamics. Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.

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Statistical parsimony network, combined mtDNA dataset, Cyclopodia horsfieldi.
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Figure 7: Statistical parsimony network, combined mtDNA dataset, Cyclopodia horsfieldi.

Mentions: Phylogenetic analyses of the combined mtDNA data set using ML (Figure 4) and MP (Figure 5) showed little resolution of population genetic structure for C. horsfieldi sampled across sites in Southeast Asia. No significant population structure that corresponded to either geography or host species was detected in any of the analyses (Figures 4, 6, 7). Despite an almost complete lack of resolution, some flies from geographically distant areas formed clades with greater than 50% support in the MP tree (e.g. PT13, KB4, and CM3, from Peninsular Malaysia and Vietnam), also evident in the Bayesian tree (Figure 6). Bat flies collected from Pualu Pangkor (PPH), off the west coast of Peninsular Malaysia, appear to be distinct in the haplotype network (Figure 7, yellow), but several individuals shared identical haplotype sequences with flies collected 300 km away on the east coast of Malaysia from Pulau Perhentian (PER) (Figure 7). The most genetically divergent bat fly individual, RC24, was a male morphologically indistinguishable from all the other Cyclopodia horsfieldi specimens.


Lack of population genetic structure and host specificity in the bat fly, Cyclopodia horsfieldi, across species of Pteropus bats in Southeast Asia.

Olival KJ, Dick CW, Simmons NB, Morales JC, Melnick DJ, Dittmar K, Perkins SL, Daszak P, Desalle R - Parasit Vectors (2013)

Statistical parsimony network, combined mtDNA dataset, Cyclopodia horsfieldi.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750525&req=5

Figure 7: Statistical parsimony network, combined mtDNA dataset, Cyclopodia horsfieldi.
Mentions: Phylogenetic analyses of the combined mtDNA data set using ML (Figure 4) and MP (Figure 5) showed little resolution of population genetic structure for C. horsfieldi sampled across sites in Southeast Asia. No significant population structure that corresponded to either geography or host species was detected in any of the analyses (Figures 4, 6, 7). Despite an almost complete lack of resolution, some flies from geographically distant areas formed clades with greater than 50% support in the MP tree (e.g. PT13, KB4, and CM3, from Peninsular Malaysia and Vietnam), also evident in the Bayesian tree (Figure 6). Bat flies collected from Pualu Pangkor (PPH), off the west coast of Peninsular Malaysia, appear to be distinct in the haplotype network (Figure 7, yellow), but several individuals shared identical haplotype sequences with flies collected 300 km away on the east coast of Malaysia from Pulau Perhentian (PER) (Figure 7). The most genetically divergent bat fly individual, RC24, was a male morphologically indistinguishable from all the other Cyclopodia horsfieldi specimens.

Bottom Line: AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations.We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact.Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.

View Article: PubMed Central - HTML - PubMed

Affiliation: EcoHealth Alliance, New York, NY 10001, USA. olival@ecohealthalliance.org

ABSTRACT

Background: Population-level studies of parasites have the potential to elucidate patterns of host movement and cross-species interactions that are not evident from host genealogy alone. Bat flies are obligate and generally host-specific blood-feeding parasites of bats. Old-World flies in the family Nycteribiidae are entirely wingless and depend on their hosts for long-distance dispersal; their population genetics has been unstudied to date.

Methods: We collected a total of 125 bat flies from three Pteropus species (Pteropus vampyrus, P. hypomelanus, and P. lylei) from eight localities in Malaysia, Cambodia, and Vietnam. We identified specimens morphologically and then sequenced three mitochondrial DNA gene fragments (CoI, CoII, cytB; 1744 basepairs total) from a subset of 45 bat flies. We measured genetic diversity, molecular variance, and population genetic subdivision (FST), and used phylogenetic and haplotype network analyses to quantify parasite genetic structure across host species and localities.

Results: All flies were identified as Cyclopodia horsfieldi with the exception of two individuals of Eucampsipoda sundaica. Low levels of population genetic structure were detected between populations of Cyclopodia horsfieldi from across a wide geographic range (~1000 km), and tests for isolation by distance were rejected. AMOVA results support a lack of geographic and host-specific population structure, with molecular variance primarily partitioned within populations. Pairwise FST values from flies collected from island populations of Pteropus hypomelanus in East and West Peninsular Malaysia supported predictions based on previous studies of host genetic structure.

Conclusions: The lack of population genetic structure and morphological variation observed in Cyclopodia horsfieldi is most likely due to frequent contact between flying fox species and subsequent high levels of parasite gene flow. Specifically, we suggest that Pteropus vampyrus may facilitate movement of bat flies between the three Pteropus species in the region. We demonstrate the utility of parasite genetics as an additional layer of information to measure host movement and interspecific host contact. These approaches may have wide implications for understanding zoonotic, epizootic, and enzootic disease dynamics. Bat flies may play a role as vectors of disease in bats, and their competence as vectors of bacterial and/or viral pathogens is in need of further investigation.

Show MeSH
Related in: MedlinePlus