Research Group Spermatophytes, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, Gent, 9000, Belgium.
Botanic Garden Meise, Nieuwelaan 38, Meise, 1860, Belgium.
Heredity (Edinb). 2019 Apr;122(4):485-500. doi: 10.1038/s41437-018-0151-5. Epub 2018 Oct 27.
Conserving tree populations safeguards forests since they represent key elements of the ecosystem. The genetic characteristics underlying the evolutionary success of the tree growth form: high genetic diversity, extensive gene flow and strong species integrity, contribute to their survival in terms of adaptability. However, different biological and landscape contexts challenge these characteristics. This study employs 63 de novo developed microsatellite or SSR (Single Sequence Repeat) markers in different datasets of nine Neotropical Magnolia species. The genetic patterns of these protogynous, insect-pollinated tree species occurring in fragmented, highly-disturbed landscapes were investigated. Datasets containing a total of 340 individuals were tested for their genetic structure and degree of inbreeding. Analyses for genetic structure depicted structuring between species, i.e. strong species integrity. Within the species, all but one population pair were considered moderate to highly differentiated, i.e. no indication of extensive gene flow between populations. No overall correlation was observed between genetic and geographic distance of the pairwise species' populations. In contrast to the pronounced genetic structure, there was no evidence of inbreeding within the populations, suggesting mechanisms favouring cross pollination and/or selection for more genetically diverse, heterozygous offspring. In conclusion, the data illustrate that the Neotropical Magnolias in the context of a fragmented landscape still have ample gene flow within populations, yet little gene flow between populations.
保护树种种群有助于维护森林，因为它们是生态系统的关键组成部分。树木生长形式的进化成功所依赖的遗传特征：高度的遗传多样性、广泛的基因流和强大的物种完整性，有助于它们在适应能力方面的生存。然而，不同的生物和景观背景条件对这些特征提出了挑战。本研究采用了 63 种新开发的微卫星或 SSR（单序列重复）标记，用于九种新热带木莲属物种的不同数据集。对这些存在于碎片化、高度干扰景观中的雌雄异熟、昆虫授粉树种的遗传模式进行了研究。对包含总共 340 个个体的数据集进行了遗传结构和近交程度的测试。遗传结构分析表明存在种间结构，即强烈的物种完整性。在种内，除了一对种群外，所有种群都被认为是中度到高度分化的，即没有种群间广泛基因流的迹象。没有观察到遗传距离和成对种群的地理距离之间的总体相关性。与明显的遗传结构相反，种群内没有近交的证据，这表明有利于异花授粉的机制和/或选择更多遗传多样化、杂合子后代的机制。总之，这些数据表明，在破碎化景观背景下的新热带木莲属树种在种群内仍有充足的基因流，但种群间的基因流很少。
