Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group
1
Department of Biological Sciences, Galvin Life Sciences Bldg., University of Notre Dame, Notre Dame, IN 46556, USA
2
Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN 46556, USA
3
Michigan State University, Department of Entomology and Lyman Briggs College, East Holmes Hall, E. Lansing, MI 48824, USA
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United States Department of Agriculture, Agricultural Research Service, Temperate Tree Fruit and Vegetable Research Unit, 5230 Konnowac Pass Road, Wapato, WA 98951, USA
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Washington State University Extension, 1919 NE 78th Street, Vancouver, WA 98665, USA
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PROIMI Biotecnología-CONICET, LIEMEN-División Control Biológico de Plagas, Av. Belgrano y Pje. Caseros, T4001MVB San Miguel de Tucumán, Tucumán, Argentina
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Instituto de Ecología, A.C., Carretera Antigua a Coatepec no. 351, Congregación el Haya, C.P. 91070 Xalapa, Veracruz, Mexico
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Environmental Change Initiative, University of Notre Dame, Notre Dame, IN 46556, USA
*
Author to whom correspondence should be addressed.
†
Current Address: Faculty of Science and Technology, Free University of Bozen-Bolzano, 39100 Bozen-Bolzano, Italy.
‡
Current Address: Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
§
Current Address: Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77088, USA.
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Current Address: Department of Biological Sciences, Binghamton University, Binghamton, NY 13902, USA.
Insects 2019, 10(9), 275; https://doi.org/10.3390/insects10090275
Received: 31 July 2019 / Revised: 26 August 2019 / Accepted: 27 August 2019 / Published: 29 August 2019
(This article belongs to the Special Issue Cutting-Edge Evolution of Insects: Factors Governing Ecological Divergence of Natural Populations Assessed Using Molecular and Genetic Markers)
Ascertaining the causes of adaptive radiation is central to understanding how new species arise and come to vary with their resources. The ecological theory posits adaptive radiation via divergent natural selection associated with novel resource use; an alternative suggests character displacement following speciation in allopatry and then secondary contact of reproductively isolated but ecologically similar species. Discriminating between hypotheses, therefore, requires the establishment of a key role for ecological diversification in initiating speciation versus a secondary role in facilitating co-existence. Here, we characterize patterns of genetic variation and postzygotic reproductive isolation for tephritid fruit flies in the Rhagoletis cingulata sibling species group to assess the significance of ecology, geography, and non-adaptive processes for their divergence. Our results support the ecological theory: no evidence for intrinsic postzygotic reproductive isolation was found between two populations of allopatric species, while nuclear-encoded microsatellites implied strong ecologically based reproductive isolation among sympatric species infesting different host plants. Analysis of mitochondrial DNA suggested, however, that cytoplasmic-related reproductive isolation may also exist between two geographically isolated populations within R cingulata. Thus, ecology associated with sympatric host shifts and cytoplasmic effects possibly associated with an endosymbiont may be the key initial drivers of the radiation of the R. cingulata group.
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Keywords:
adaptive radiation; speciation; sympatry; allopatry; reproductive isolation
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MDPI and ACS Style
Doellman, M.M.; Schuler, H.; Jean Saint, G.; Hood, G.R.; Egan, S.P.; Powell, T.H.; Glover, M.M.; Bruzzese, D.J.; Smith, J.J.; Yee, W.L.; Goughnour, R.B.; Rull, J.; Aluja, M.; Feder, J.L. Geographic and Ecological Dimensions of Host Plant-Associated Genetic Differentiation and Speciation in the Rhagoletis cingulata (Diptera: Tephritidae) Sibling Species Group. Insects 2019, 10, 275.
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