Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores

Abstract The evolutionary trajectory of island populations can be rapidly altered by human-mediated migration, a process further exacerbated when immigrants introduce invasive parasites, creating new selective pressures. Using customised SNP panels constructed with genome-wide diagnostic loci, we de...

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Main Authors: Dora Henriques, Ana R. Lopes, Matthew Low, M. Alice Pinto
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-08950-y
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author Dora Henriques
Ana R. Lopes
Matthew Low
M. Alice Pinto
author_facet Dora Henriques
Ana R. Lopes
Matthew Low
M. Alice Pinto
author_sort Dora Henriques
collection DOAJ
description Abstract The evolutionary trajectory of island populations can be rapidly altered by human-mediated migration, a process further exacerbated when immigrants introduce invasive parasites, creating new selective pressures. Using customised SNP panels constructed with genome-wide diagnostic loci, we describe the genetic changes in honey bee populations inhabiting the Azores archipelago. As part of a breeding initiative in the 1980s, these populations were recurrently exposed to beekeeper-mediated gene flow from a highly divergent commercial line (C lineage) until the arrival of the Varroa mite to the Azores in 2000, which prompted a honey bee importation ban. Admixture analysis revealed a spatially heterogeneous introgression landscape in the Azores. Four of the five mite-free islands (Santa Maria, São Miguel, Terceira, and São Jorge) presented negligible levels of C-lineage introgression (mean Q-value: 0.004–0.091) despite repeated C-lineage importations in the past. In contrast, the three mite-infested islands (Pico, Faial, and Flores) presented high levels of introgression (mean Q-value: 0.156–0.261). The mite-free island of Graciosa harboured the most admixed population (mean Q-value: 0.392), which is consistent with efforts to eradicate the historical population and replace it with C-lineage honey bees during the implementation of the breeding program. Bayesian inference modelling indicated that the presence of a C-lineage maternal origin and Varroa were associated with increased introgression proportions (100% posterior probability), increasing the mean Q-value by 0.049 and 0.118, respectively. Our findings indicate that these anthropogenic processes altered the historically introduced gene pool and provide a foundation for developing effective conservation strategies to protect honey bees in the Azores.
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spelling doaj-art-e8b83c89d3d44df1bf0588c36762927a2025-08-20T03:42:53ZengNature PortfolioScientific Reports2045-23222025-07-0115111210.1038/s41598-025-08950-yHuman-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the AzoresDora Henriques0Ana R. Lopes1Matthew Low2M. Alice Pinto3CIMO, LA SusTEC, Instituto Politécnico de BragançaCIMO, LA SusTEC, Instituto Politécnico de BragançaDepartment of Ecology, Swedish University of Agricultural SciencesCIMO, LA SusTEC, Instituto Politécnico de BragançaAbstract The evolutionary trajectory of island populations can be rapidly altered by human-mediated migration, a process further exacerbated when immigrants introduce invasive parasites, creating new selective pressures. Using customised SNP panels constructed with genome-wide diagnostic loci, we describe the genetic changes in honey bee populations inhabiting the Azores archipelago. As part of a breeding initiative in the 1980s, these populations were recurrently exposed to beekeeper-mediated gene flow from a highly divergent commercial line (C lineage) until the arrival of the Varroa mite to the Azores in 2000, which prompted a honey bee importation ban. Admixture analysis revealed a spatially heterogeneous introgression landscape in the Azores. Four of the five mite-free islands (Santa Maria, São Miguel, Terceira, and São Jorge) presented negligible levels of C-lineage introgression (mean Q-value: 0.004–0.091) despite repeated C-lineage importations in the past. In contrast, the three mite-infested islands (Pico, Faial, and Flores) presented high levels of introgression (mean Q-value: 0.156–0.261). The mite-free island of Graciosa harboured the most admixed population (mean Q-value: 0.392), which is consistent with efforts to eradicate the historical population and replace it with C-lineage honey bees during the implementation of the breeding program. Bayesian inference modelling indicated that the presence of a C-lineage maternal origin and Varroa were associated with increased introgression proportions (100% posterior probability), increasing the mean Q-value by 0.049 and 0.118, respectively. Our findings indicate that these anthropogenic processes altered the historically introduced gene pool and provide a foundation for developing effective conservation strategies to protect honey bees in the Azores.https://doi.org/10.1038/s41598-025-08950-yApis melliferaVarroa destructorIntrogressionConservationAzores
spellingShingle Dora Henriques
Ana R. Lopes
Matthew Low
M. Alice Pinto
Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
Scientific Reports
Apis mellifera
Varroa destructor
Introgression
Conservation
Azores
title Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
title_full Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
title_fullStr Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
title_full_unstemmed Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
title_short Human-mediated introgression and Varroa destructor shaped the genetic structure of honey bee populations in the Azores
title_sort human mediated introgression and varroa destructor shaped the genetic structure of honey bee populations in the azores
topic Apis mellifera
Varroa destructor
Introgression
Conservation
Azores
url https://doi.org/10.1038/s41598-025-08950-y
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