瑞士联邦理工学院Delavaux, Camille S.课题组在研究中取得进展。他们揭示了互利共生削弱了海洋岛屿间的纬度多样性梯度。2024年2月28日出版的《自然》发表了这项成果。

研究人员使用了一个独特的全球数据，数据显示，海洋岛屿上的维管植物表现出较弱的LDG，研究人员还探讨了这种影响的潜在机制。结果表明，岛屿生物地理学的传统物理驱动因素（即面积和隔离），导致了给定纬度下岛屿和大陆多样性的差异(即岛屿物种赤字)，因为更小、更遥远的岛屿经历了较少的殖民化。然而，岛屿上具有共生关系的植物物种代表性不足，研究发现这种植物互利共生过滤器比非生物因素更能解释岛屿物种赤字的变化。

特别是，需要动物传粉的植物物种或微生物共生物种，如丛枝菌根真菌，对赤道附近岛屿物种赤字的贡献不成比例，这种影响随着离赤道的距离增加而减少。在大陆物种丰富度最高的低纬度地区，植物相互作用对物种丰富度的过滤作用特别强，削弱了海洋岛屿的LDG。研究结果表明，热带地区植物多样性多样性的多样性是由互利共生关系、生境异质性和扩散机制决定的，并在一定程度上调节着热带地区植物多样性的生物地理格局。

据悉，纬向多样性梯度(LDG)主导着全球多样性模式，但纬向多样性梯度背后的因素仍处令人难以捉摸。

附：英文原文

Title: Mutualisms weaken the latitudinal diversity gradient among oceanic islands

Author: Delavaux, Camille S., Crowther, Thomas W., Bever, James D., Weigelt, Patrick, Gora, Evan M.

Issue&Volume: 2024-02-28

Abstract: The latitudinal diversity gradient (LDG) dominates global patterns of diversity, but the factors that underlie the LDG remain elusive. Here we use a unique global dataset to show that vascular plants on oceanic islands exhibit a weakened LDG and explore potential mechanisms for this effect. Our results show that traditional physical drivers of island biogeography—namely area and isolation—contribute to the difference between island and mainland diversity at a given latitude (that is, the island species deficit), as smaller and more distant islands experience reduced colonization. However, plant species with mutualists are underrepresented on islands, and we find that this plant mutualism filter explains more variation in the island species deficit than abiotic factors. In particular, plant species that require animal pollinators or microbial mutualists such as arbuscular mycorrhizal fungi contribute disproportionately to the island species deficit near the Equator, with contributions decreasing with distance from the Equator. Plant mutualist filters on species richness are particularly strong at low absolute latitudes where mainland richness is highest, weakening the LDG of oceanic islands. These results provide empirical evidence that mutualisms, habitat heterogeneity and dispersal are key to the maintenance of high tropical plant diversity and mediate the biogeographic patterns of plant diversity on Earth.

DOI: 10.1038/s41586-024-07110-y

Source: https://www.nature.com/articles/s41586-024-07110-y