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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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Sampling localities for Cyclopodia horsfieldi (with total flies collected/sequenced) from three Pteropus species in Southeast Asia.
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Figure 1: Sampling localities for Cyclopodia horsfieldi (with total flies collected/sequenced) from three Pteropus species in Southeast Asia.

Mentions: We collected bat flies from three species of flying fox (Pteropus hypomelanus, P. vampyrus, and P. lylei) from localities across Southeast Asia (Figure 1, Table 1). In Malaysia, canopy mist nets were deployed near diurnal roosting trees or nearby feeding sites, and bats were immediately removed upon capture and held individually in cloth bags for ~1 hr before sampling. Bats were anesthetized using medetomidine/ketamine (0.025/2.5 mg/kg) administered intramuscularly or were restrained without anesthesia to collect ectoparasites and wing biopsies for host DNA [35]. Bat flies were collected with forceps by examining the pelage of anesthetized or restrained bats, and placed directly in 95% ethanol for preservation. All bats were handled and sampled in accordance with IACUC protocol (#AAAA3272) from Columbia University. GPS coordinates were recorded for all sampling localities at the point of capture, although in Vietnam and Cambodia local hunters captured bats alive in mist nets near feeding sites and the exact roost localities were not known but likely within 50 km of the sampling site. All bats were marked, photographed, and released at the site of capture except for individuals of P. lylei and P. vampyrus from Vietnam which were collected as voucher specimens currently accessioned at the Institute for Ecology and Biological Resources, Hanoi, Vietnam. From July 2004-May 2007, a total of 125 bat flies were collected from 66 individuals of the three host species (Table 1). Fly specimens are currently accessioned at Western Kentucky University, State University of New York at Buffalo, and the American Museum of Natural History. Sampling was not evenly distributed across host species; 104 flies were collected from three populations of P. hypomelanus, 17 flies from P. vampyrus, and four flies from P. lylei.


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)

Sampling localities for Cyclopodia horsfieldi (with total flies collected/sequenced) from three Pteropus species in Southeast Asia.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: Sampling localities for Cyclopodia horsfieldi (with total flies collected/sequenced) from three Pteropus species in Southeast Asia.
Mentions: We collected bat flies from three species of flying fox (Pteropus hypomelanus, P. vampyrus, and P. lylei) from localities across Southeast Asia (Figure 1, Table 1). In Malaysia, canopy mist nets were deployed near diurnal roosting trees or nearby feeding sites, and bats were immediately removed upon capture and held individually in cloth bags for ~1 hr before sampling. Bats were anesthetized using medetomidine/ketamine (0.025/2.5 mg/kg) administered intramuscularly or were restrained without anesthesia to collect ectoparasites and wing biopsies for host DNA [35]. Bat flies were collected with forceps by examining the pelage of anesthetized or restrained bats, and placed directly in 95% ethanol for preservation. All bats were handled and sampled in accordance with IACUC protocol (#AAAA3272) from Columbia University. GPS coordinates were recorded for all sampling localities at the point of capture, although in Vietnam and Cambodia local hunters captured bats alive in mist nets near feeding sites and the exact roost localities were not known but likely within 50 km of the sampling site. All bats were marked, photographed, and released at the site of capture except for individuals of P. lylei and P. vampyrus from Vietnam which were collected as voucher specimens currently accessioned at the Institute for Ecology and Biological Resources, Hanoi, Vietnam. From July 2004-May 2007, a total of 125 bat flies were collected from 66 individuals of the three host species (Table 1). Fly specimens are currently accessioned at Western Kentucky University, State University of New York at Buffalo, and the American Museum of Natural History. Sampling was not evenly distributed across host species; 104 flies were collected from three populations of P. hypomelanus, 17 flies from P. vampyrus, and four flies from P. lylei.

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