Abstract. The study of the morphology of living organisms is essential to understand their evolution and diversity. This study aims to determine the importance of climatic gradients in the diversity of pollen morphotypes using Atriplex halimus L. (Amaranthaceae) as a model species. Atriplex halimus is a perennial shrubby plant, polymorphic and very resistant to severe environmental conditions. In seven bioclimatic zones, ranging from mesic conditions in the north to hot–hyperarid in the south, pollen samples were collected from 49 sites, with seven accessions per bioclimate. Under a light microscope, pollen grains were selected and analyzed from three anthers of different flowers. Besides the usual pollen grain types, some previously unknown morphotypes, such as sulcate, triangular, and ovoid, were observed and described at the different climatic zones. A total of 10 pollen grain shapes were quantified and discussed following their specific occurrences within different climatic zones. Occurrence frequencies of different pollen shapes ranged between 0 % and 85.7 %, where the pantoporate spheroidal was the most widespread in all climatic zones, especially in the desert climate (85.7 %). Five pollen types occurred exclusively once per climate zone. The pantoporate prolate spheroidal in mesomediterranean climate with a long dry season (28.6 %), sulcate in the xerothermomediterranean climate (14.3%), pantoporate subtriangular in the subdesert climate with a short dry season (14.3 %), and pantoporate subprolate and boat-shaped in a subdesert climate with a long dry season with 14.3 % for each. Our findings help to understand the evolutionary effects of climate gradients on pollen morphology and variability in arid and desert areas and point towards a high degree of specialization in order to maximize trade-offs between pollination efficiency and protection of pollen grains from dehydration.

中文翻译：

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花粉形态变异与大尺度干旱梯度相关

摘要。研究生物体的形态对于了解它们的进化和多样性至关重要。本研究旨在确定气候梯度在使用 Atriplex halimus L.（苋科）作为模型物种的花粉形态多样性中的重要性。Atriplex halimus 是一种多年生灌木植物，多态性，对恶劣的环境条件具有很强的抵抗力。在 7 个生物气候带，从北部的温和条件到南部的高温干旱，从 49 个地点收集了花粉样本，每个生物气候有 7 个种质。在光学显微镜下，从不同花的三种花药中选择并分析花粉粒。除了通常的花粉粒类型外，还有一些以前未知的形态类型，例如槽状、三角形和卵球形，在不同的气候带进行了观察和描述。总共 10 种花粉粒形状被量化并讨论了它们在不同气候带内的具体发生情况。不同花粉形状的出现频率在0%~85.7%之间，其中泛孔状球体在所有气候带中分布最广，尤其是在沙漠气候中（85.7%）。五种花粉类型在每个气候区只出现一次。旱季长的中地中海气候中的 pantoporate 长椭球体 (28.6%)，干热地中海气候中的槽状 (14.3%)，旱季短的亚沙漠气候中的 pantoporate subtriangular (14.3%)，以及 pantoporate 形的 subprolate 和船形在干旱季节长的沙漠气候中，每个人的 14.3%。