Genetic structure of dioecious and trioecious Salix myrsinifolia populations at the border of geographic range

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• 作者：P. Mirski ; E. Brzosko ; I. Jędrzejczyk ; J. Kotowicz…
• 关键词：Sex structure ; Trioecy ; Dioecy ; Subdioecy ; AFLP
• 刊名：Tree Genetics & Genomes
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：13
• 期：1
• 全文大小：2201KB
• 刊物主题：Forestry; Plant Genetics & Genomics; Plant Breeding/Biotechnology; Tree Biology; Biotechnology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1614-2950
• 卷排序：13

文摘

Gene flow in plant populations is heavily affected by species sexual systems. In order to study the effect of sexual systems on genetic structure, we examined plastid and nuclear DNA of 12 dioecious (males and females) and 18 trioecious (males, females and hermaphrodites) populations of Salix myrsinifolia—a boreal shrub with slow range expansion. Populations were located along latitudinal gradients across submarginal and marginal parts of the range. Individuals of each sex morph were all hexaploid. We identified 10 chloroplast DNA haplotypes and scored 205 polymorphic bands with amplified fragment length polymorphism. We found dioecious populations that differed from trioecious populations via the presence of four unique haplotypes and significant difference in Nei’s gene diversity index (0.119 vs. 0.116) and down-weighed marker value (1.17 vs. 1.02). The latter parameter, together with haplotype and nucleotide diversity, significantly decreased with latitude similar to the expansion front. Also, we found that 89% of hermaphrodite individuals belong to one distinct in tree parsimony network haplotype. This frequency significantly decreased with latitude towards the expansion front. We suspect that the presence of hermaphrodites in trioecious populations may represent a trade-off between the possibility of producing progeny by single hermaphrodites and genetic variability loss through autogamy. S. myrsinifolia benefits from trioecious sexual systems under colonization events. This phenomenon is no longer a gain closer to the core of the species range.