THE ROLE OF INBREEDING DEPRESSION AND MATING SYSTEM IN THE EVOLUTION OF HETEROSTYLY |
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Authors: | Jennifer J Weber Stephen G Weller Ann K Sakai Olga V Tsyusko Travis C Glenn César A Domínguez Francisco E Molina‐Freaner Juan Fornoni Mike Tran Nhu Nguyen Karen Nguyen Lien‐Khuong Tran Greg Joice Ellen Harding |
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Institution: | 1. Department of Ecology and Evolutionary Biology, University of California, , Irvine, California, 92697;2. Department of Plant and Soil Sciences, University of Kentucky, , Lexington, Kentucky, 40546;3. Environmental Health Sciences, University of Georgia, , Athens, Georgia, 30602;4. Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, , 04510 México;5. Departamento de Ecología de la Biodiversidad, Estación Regional del Noroeste, Instituto de Ecología, Universidad Nacional Autónoma de México, , Hermosillo, 83000 Sonora, México |
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Abstract: | We investigated the role of morph‐based differences in the expression of inbreeding depression in loss of the mid‐styled morph from populations of tristylous Oxalis alpina. The extent of self‐compatibility (SC) of reproductive morphs, the degree of self‐fertilization, and the magnitude of inbreeding depression were investigated in three populations of O. alpina differing in their tristylous incompatibility relationships. All three populations exhibited significant inbreeding depression. In two populations with highly modified tristylous incompatibility, manifested as increased reciprocal compatibility between short‐ and long‐styled morphs, substantial SC and self‐fertilization of mid‐styled morphs were detected, and expected to result in expression of inbreeding depression in the progeny of mid‐styled morphs in the natural populations. In contrast, significant self‐fertility of the mid‐styled morph was absent from the population with typical tristylous incompatibility, and no self‐fertilization could be detected. Although self‐fertilization and expression of inbreeding depression should result in selection against the mid‐styled morph in the later stages of the transition from tristyly to distyly, in O. alpina selection against the mid‐styled morph in the early phases of the evolution of distyly is likely due to genic selection against mid‐alleles associated with modified tristylous incompatibility, rather than expression of inbreeding depression. |
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Keywords: | Breeding systems distyly Oxalidaceae self‐incompatibility tristyly |
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