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Human-facilitated metapopulation dynamics in an emerging pest species, Cimex lectularius.

Fountain T, Duvaux L, Horsburgh G, Reinhardt K, Butlin RK - Mol. Ecol. (2014)

Bottom Line: Founder events often result in drastic reductions in diversity and an increased influence of genetic drift.ABC results suggest a common origin of all founders of a given subpopulation and that the numbers of colonists were low, implying that even a single mated female is enough to found a new infestation successfully.These patterns of colonization are close to the predictions of the propagule pool model, where all founders originate from the same parental infestation.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK; Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.

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Demographic scenarios for ABC. Scenario one: Migrant pool model of colonization: All populations originate from a single hypothetic source population (Ns), which represents the metapopulation as a whole. At time t2, these populations diverge signifying the founding of new infestations, which includes a severe bottleneck (Nb). After a bottleneck of one generation, the populations grow and reach effective population size (Ne). It is this size at which the infestations are sampled. Scenario two: Propagule pool model of colonization: in this scenario, founders diverge from Ns at t3 and maintain a population size of Ne until t2 where there is a founding event and a severe bottleneck (Nb) of one generation. The subpopulation then grows to a size of Ne before being sampled. In both scenarios, only infestations a and b are shown, but models incorporate 13 sampled infestations, represented by the dotted line.
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fig01: Demographic scenarios for ABC. Scenario one: Migrant pool model of colonization: All populations originate from a single hypothetic source population (Ns), which represents the metapopulation as a whole. At time t2, these populations diverge signifying the founding of new infestations, which includes a severe bottleneck (Nb). After a bottleneck of one generation, the populations grow and reach effective population size (Ne). It is this size at which the infestations are sampled. Scenario two: Propagule pool model of colonization: in this scenario, founders diverge from Ns at t3 and maintain a population size of Ne until t2 where there is a founding event and a severe bottleneck (Nb) of one generation. The subpopulation then grows to a size of Ne before being sampled. In both scenarios, only infestations a and b are shown, but models incorporate 13 sampled infestations, represented by the dotted line.

Mentions: The two scenarios used in our ABC analysis are illustrated in Fig. 1. For both, we simulated 20 microsatellites from 13 infestations using the same sample size per infestation as obtained from the field (Table3). Note that from our 21 original microsatellites, the locus Cle001 was omitted, due to a large range of allele sizes that reduced our ability to fit the models. For the migrant pool model, we approximated the multiple origins of new infestations by randomly drawing individuals from a large panmictic population serving as a proxy for the metapopulation (scenario one). The propagule pool model was designed such that colonists founding a particular infestation all came from the same source infestation, itself derived from the large panmictic population (scenario two; Fig. 1). In both cases, we would expect a severe bottleneck at the point of founding, followed by a period of rapid growth. Because infestations are believed to be invariably settled through strong bottlenecks and to have short lifespans, we do not expect them to differ widely in age at sampling time or in effective population size. We thus simplified the models by constraining Ne, t2 and t3 to be shared by all infestations.


Human-facilitated metapopulation dynamics in an emerging pest species, Cimex lectularius.

Fountain T, Duvaux L, Horsburgh G, Reinhardt K, Butlin RK - Mol. Ecol. (2014)

Demographic scenarios for ABC. Scenario one: Migrant pool model of colonization: All populations originate from a single hypothetic source population (Ns), which represents the metapopulation as a whole. At time t2, these populations diverge signifying the founding of new infestations, which includes a severe bottleneck (Nb). After a bottleneck of one generation, the populations grow and reach effective population size (Ne). It is this size at which the infestations are sampled. Scenario two: Propagule pool model of colonization: in this scenario, founders diverge from Ns at t3 and maintain a population size of Ne until t2 where there is a founding event and a severe bottleneck (Nb) of one generation. The subpopulation then grows to a size of Ne before being sampled. In both scenarios, only infestations a and b are shown, but models incorporate 13 sampled infestations, represented by the dotted line.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016754&req=5

fig01: Demographic scenarios for ABC. Scenario one: Migrant pool model of colonization: All populations originate from a single hypothetic source population (Ns), which represents the metapopulation as a whole. At time t2, these populations diverge signifying the founding of new infestations, which includes a severe bottleneck (Nb). After a bottleneck of one generation, the populations grow and reach effective population size (Ne). It is this size at which the infestations are sampled. Scenario two: Propagule pool model of colonization: in this scenario, founders diverge from Ns at t3 and maintain a population size of Ne until t2 where there is a founding event and a severe bottleneck (Nb) of one generation. The subpopulation then grows to a size of Ne before being sampled. In both scenarios, only infestations a and b are shown, but models incorporate 13 sampled infestations, represented by the dotted line.
Mentions: The two scenarios used in our ABC analysis are illustrated in Fig. 1. For both, we simulated 20 microsatellites from 13 infestations using the same sample size per infestation as obtained from the field (Table3). Note that from our 21 original microsatellites, the locus Cle001 was omitted, due to a large range of allele sizes that reduced our ability to fit the models. For the migrant pool model, we approximated the multiple origins of new infestations by randomly drawing individuals from a large panmictic population serving as a proxy for the metapopulation (scenario one). The propagule pool model was designed such that colonists founding a particular infestation all came from the same source infestation, itself derived from the large panmictic population (scenario two; Fig. 1). In both cases, we would expect a severe bottleneck at the point of founding, followed by a period of rapid growth. Because infestations are believed to be invariably settled through strong bottlenecks and to have short lifespans, we do not expect them to differ widely in age at sampling time or in effective population size. We thus simplified the models by constraining Ne, t2 and t3 to be shared by all infestations.

Bottom Line: Founder events often result in drastic reductions in diversity and an increased influence of genetic drift.ABC results suggest a common origin of all founders of a given subpopulation and that the numbers of colonists were low, implying that even a single mated female is enough to found a new infestation successfully.These patterns of colonization are close to the predictions of the propagule pool model, where all founders originate from the same parental infestation.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK; Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland.

Show MeSH
Related in: MedlinePlus