BACKGROUNDS AND AIMS Dimorphandra wilsonii Rizzini, a critically endangered and protected tree, has a restricted distribution in the ecotone between the Cerrado and the Atlantic Forest in southeastern Brazil. In this area, it co-occurs with D. mollis Benth., a common tree from the Cerrado, and D. exaltata Schott., a rare tree from the Atlantic Forest. Previous studies of D. wilsonii indicated heterozygosity excess at the individual level. Field observation of some intermediate phenotypes between D. wilsonii and both congeners suggests hybridization of D. wilsonii with D. mollis and/or D. exaltata. Here, we tested the hypothesis that D. wilsonii may be originated from hybridization between D. exaltata and D. mollis. We also performed cytogenetic analysis to examine if the heterozygote excess could be explained by polyploidy in D. wilsonii. METHODS We evaluated the genetic diversity and population structure of D. wilsonii using eleven nuclear SSRs genotyped in 152 individuals sampled across the taxon's range. We performed comparative genetic analyses using overlapping SSR markers between D. wilsonii and previously published SSR data in D. mollis and D. exaltata to perform a series of allelic comparisons, multivariate and Bayesian analysis. KEY RESULTS Our results suggest that D. wilsonii individuals most likely correspond to F1 hybrids between D. exaltata and D. mollis. Cytogenetic analysis indicated that D. wilsonii is diploid with the same chromosome number as D. mollis (2n = 2x = 28). CONCLUSIONS Our study raises questions about the taxonomic status and the evolutionary future of D. wilsonii. We suggest that the conservation and management strategy for D. wilsonii should be revised and that it should take into account both parental Dimorphandra species in the ecotone, with special emphasis on the threatened D. exaltata. Finally, this study highlights the value of genetic information for the design of conservation strategies.

中文翻译：

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受保护的树 Dimorphandra wilsonii（豆科）是种间杂交种群：巴西塞拉多/大西洋森林交错带的保护建议


背景和目的 Dimorphandra wilsonii Rizzini 是一种极度濒危和受保护的树种，在巴西东南部塞拉多和大西洋森林之间的生态交错带中分布有限。在该地区，它与来自塞拉多的常见树 D. mollis Benth. 和来自大西洋森林的稀有树 D. exaltata Schott. 共生。先前对 D. wilsonii 的研究表明个体水平上存在杂合性过剩。对 D. wilsonii 和两种同系物之间的一些中间表型的现场观察表明 D. wilsonii 与 D. mollis 和/或 D. exaltata 杂交。在这里，我们检验了 D. wilsonii 可能起源于 D. exaltata 和 D. mollis 杂交的假设。我们还进行了细胞遗传学分析，以检查 D. wilsonii 中的杂合子过多是否可以用多倍体来解释。方法 我们使用对整个分类群范围内的 152 个个体进行基因分型的 11 个核 SSR 来评估 D. wilsonii 的遗传多样性和种群结构。我们使用 D. wilsonii 之间重叠的 SSR 标记和之前发表的 D. mollis 和 D. exaltata 中的 SSR 数据进行了比较遗传分析，以进行一系列等位基因比较、多变量和贝叶斯分析。主要结果 我们的结果表明 D. wilsonii 个体最有可能对应于 D. exaltata 和 D. mollis 之间的 F1 杂交种。细胞遗传学分析表明，D. wilsonii 是二倍体，其染色体数目与 D. mollis 相同（2n = 2x = 28）。结论 我们的研究对 D. wilsonii 的分类地位和进化未来提出了疑问。我们建议D.的保护和管理策略。 wilsonii 应该进行修订，并且应该考虑到生态交错带中的双形双形亲本物种，特别强调受威胁的双形双形属物种。最后，本研究强调了遗传信息对于保护策略设计的价值。