Kost Matthew A, Alexander Helen M, Jason Emry D, Mercer Kristin L
Department of Horticulture and Crop Science, The Ohio State University Wooster, OH, USA.
Department of Ecology and Evolutionary Biology, University of Kansas Lawrence, KS, USA.
Evol Appl. 2015 Jun;8(5):510-24. doi: 10.1111/eva.12261. Epub 2015 May 12.
Hybridization produces strong evolutionary forces. In hybrid zones, selection can differentially occur on traits and selection intensities may differ among hybrid generations. Understanding these dynamics in crop-wild hybrid zones can clarify crop-like traits likely to introgress into wild populations and the particular hybrid generations through which introgression proceeds. In a field experiment with four crop-wild hybrid Helianthus annuus (sunflower) cross types, we measured growth and life history traits and performed phenotypic selection analysis on early season traits to ascertain the likelihood, and routes, of crop allele introgression into wild sunflower populations. All cross types overwintered, emerged in the spring, and survived until flowering, indicating no early life history barriers to crop allele introgression. While selection indirectly favored earlier seedling emergence and taller early season seedlings, direct selection only favored greater early season leaf length. Further, there was cross type variation in the intensity of selection operating on leaf length. Thus, introgression of multiple early season crop-like traits, due to direct selection for greater early season leaf length, should not be impeded by any cross type and may proceed at different rates among generations. In sum, alleles underlying early season sunflower crop-like traits are likely to introgress into wild sunflower populations.
杂交会产生强大的进化力量。在杂交区域，选择可能会在性状上有差异地发生，并且选择强度在不同杂交世代之间可能会有所不同。了解作物 - 野生杂交区域中的这些动态，能够阐明可能渗入野生种群的类似作物的性状，以及基因渗入所经过的特定杂交世代。在一项针对四种作物 - 野生杂交向日葵（Helianthus annuus）杂交类型的田间试验中，我们测量了生长和生活史性状，并对早期性状进行了表型选择分析，以确定作物等位基因渗入野生向日葵种群的可能性和途径。所有杂交类型都成功越冬，在春季出苗，并存活至开花，这表明在作物等位基因渗入方面不存在早期生活史障碍。虽然选择间接有利于更早的幼苗出苗和更高的早期幼苗，但直接选择仅有利于更大的早期叶片长度。此外，在对叶片长度的选择强度上存在杂交类型差异。因此，由于对更大的早期叶片长度进行直接选择，多个早期类似作物性状的基因渗入不应受到任何杂交类型的阻碍，并且在不同世代之间可能以不同速率进行。总之，向日葵早期类似作物性状的潜在等位基因很可能渗入野生向日葵种群。
