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Niche similarity in diploid‐autotetraploid contact zones of Arabidopsis arenosa across spatial scales
American Journal of Botany ( IF 3 ) Pub Date : 2020-09-25 , DOI: 10.1002/ajb2.1534
Emma J Morgan 1 , Martin Čertner 1, 2 , Magdalena Lučanová 1, 2, 3 , Kateřina Kubíková 1 , Karol Marhold 1, 4 , Filip Kolář 1, 2, 5
Affiliation  

PREMISE Whole genome duplication is a major evolutionary event, but its role in ecological divergence remains equivocal. When populations of different ploidy (cytotypes) overlap in space, "contact zones" are formed, allowing the study of evolutionary mechanisms contributing toward ploidy divergence. Multiple contact zones per species' range are often described but rarely leveraged as natural replicates. We explored whether the strength of niche differentiation of diploid and autotetraploid Arabidopsis arenosa varies over distinct contact zones and if the frequency of triploids decreases from seedling to adult stage. METHODS We characterized ploidy composition and habitat preferences in 264 populations across three contact zones using climatic niche modeling. Ecological differences of cytotypes were also assessed using local vegetation surveys at 110 populations within two contact zones, and at the finer scale within five mixed-ploidy sites. This was complemented by flow cytometry of seedlings. RESULTS We found no niche differences between diploid and tetraploid populations within contact zones for either climatic or local environmental variables. Comparisons of cytotypes within mixed-ploidy sites found weak niche differences that were inconsistent in direction. Triploid individuals were virtually absent (0.14%) in the field, and they were at a similarly low frequency (0.2%) in ex situ germinated seedlings. CONCLUSIONS This study demonstrates the strength in investigating different spatial scales across several contact zones when addressing ecological niche differentiation between ploidies. The lack of consistent habitat differentiation of ploidies across the scales and locations supports the recently emerging picture that processes other than ecological differentiation may underlie ploidy coexistence in diploid-autopolyploid systems.

中文翻译:

拟南芥二倍体-四倍体接触区空间尺度上的生态位相似性

前提 全基因组复制是一个重大的进化事件,但它在生态分化中的作用仍然模棱两可。当不同倍性(细胞型)的种群在空间中重叠时,就会形成“接触区”,从而可以研究导致倍性分化的进化机制。每个物种范围内的多个接触区经常被描述,但很少被用作自然复制品。我们探讨了二倍体和四倍体拟南芥的生态位分化强度是否在不同的接触区发生变化,以及三倍体的频率是否从幼苗到成虫阶段降低。方法我们使用气候生态位模型对跨越三个接触区的 264 个种群的倍性组成和栖息地偏好进行了表征。还使用当地植被调查对两个接触区内的 110 个种群以及五个混合倍性位点内的更精细尺度进行了评估,评估了细胞类型的生态差异。这由幼苗的流式细胞术补充。结果我们发现接触区内的二倍体和四倍体种群之间没有气候或当地环境变量的生态位差异。混合倍性位点内细胞型的比较发现方向不一致的弱生态位差异。三倍体个体在田间几乎不存在 (0.14%),并且它们在异地发芽幼苗中的频率相似 (0.2%)。结论 本研究表明,在解决倍性之间的生态位差异时,研究跨多个接触区的不同空间尺度的优势。
更新日期:2020-09-25
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