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Increased genetic differentiation in a specialist versus a generalist bee: implications for conservation

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Abstract

Oligolectic bees are specialists that collect pollen from one or a few closely related species of plants, while polylectic bees are generalists that collect pollen from both related and unrelated species of plants. Because of their more restricted range of floral hosts, it is expected that specialists persist in more isolated populations than do generalists. We present data on the population structure of two closely related bee species sampled from a super abundant floral host in the southern Atacama Desert. Pairwise comparisons of population subdivision over identical distances revealed that the specialist bee had significantly more differentiated populations in comparison to the generalist. Further, populations of the specialist had significantly less genetic variation, measured as observed and expected heterozgyosity, than those of the generalist. Our data support the hypothesis of decreased gene flow among populations of the specialist bee even at equivalent geographic distances. The resulting reductions in effective population size for specialists make them particularly prone to extinction due to both demographic and genetic reasons. Our findings have important implications for the conservation of bees and other specialist insects.

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Acknowledgements

This research was funded primarily by a National Geographic Research and Exploration Grant awarded to LP, REO, HT and LR. We are extremely grateful for the opportunities that this funding provided. Additional support for this research was obtained from the Natural Sciences and Engineering Research Council of Canada through research and discovery grants awarded to LP and through graduate scholarships to AZ and JCG. We are most grateful to Horacio Larraín, Marta Peña, and especially Alfredo Ugarte Peña who was of considerable assistance in planning and facilitating the fieldwork. We thank Asghar Porsa and Leah Gibbens for assistance with running the gels, and Dr. R.L. Minckley and Dr. J.H. Cane for providing us with their manuscripts. We thank two anonymous reviewers for providing helpful comments on the manuscript.

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Authors and Affiliations

  1. Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada

    Amro Zayed, Laurence Packer & Jennifer C. Grixti

  2. Departamento de Zoología, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile

    Luisa Ruz & Haroldo Toro

  3. Department of Science and Mathematics, Mt. Royal College, Calgary, Alberta, Canada

    Robin E. Owen

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  1. Amro Zayed
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  2. Laurence Packer
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  3. Jennifer C. Grixti
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  4. Luisa Ruz
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  5. Robin E. Owen
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  6. Haroldo Toro
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Correspondence to Amro Zayed.

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Zayed, A., Packer, L., Grixti, J.C. et al. Increased genetic differentiation in a specialist versus a generalist bee: implications for conservation. Conserv Genet 6, 1017–1026 (2005). https://doi.org/10.1007/s10592-005-9094-5

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  • DOI: https://doi.org/10.1007/s10592-005-9094-5

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