Relation between nutritional mode and ecophysiological niche widthand its effect on distribution pattern and habitat specificity ofchrysomonad flagellates

生物的分布格局、生物生态与其分布格局之间的联系以及这种格局的概括性是评价生态系统及其相关生物多样性动态性质的重要依据。生物多样性和生态系统功能之间的相互作用提出了一个问题，即分类群之间的功能分化如何与它们的分布格局有关。最明显的功能差异之一是营养策略的差异，即异养与混合营养与光营养。解决这些首要研究问题的理想目标是微生物真核生物，因为它们具有压倒性的多样性和功能分化。金藻(金藻)是一个特别适合的模型组，因为它们分布广泛，在广泛生境的优势鞭毛虫中，这一组内实现了广泛的营养策略，具有不同策略的金藻通常在许多不同的生境中共存。此外，它们得到了较好的研究，这一组的成员在生态学和生态生理学方面作为原生动物模式物种具有悠久的传统。异养体在金丝藻中独立进化了几次。在这里，我们假设，一般说来，异养类群可以耐受比混合营养类群和光营养类群更广泛的物理化学条件。因此，我们假设金藻在光生、混养和异养类群中的分布模式不同，即与它们的生态相关，而不是与它们的系统发育相关。在第一个工作包中，我们将表征黄单胞菌的生长速度作为食物和营养浓度、食物质量和光照强度的函数，作为比较分析异养和光营养菌株生态位宽度的基础。在随后的工作包中，我们将测试基本生态位宽度在异养型、混合型和光养型黄藻谱系之间存在系统性差异的假设。我们用实地调查来补充这些生态生理分析，重点是关于栖息地特征的区域分布模式。我们特别假设，与异养金藻相比，光养金藻的分布模式更多地局限于类似非生物条件的生境，并且与异养金藻相比，光养金藻的季节性更明显。总之，这项研究将为将生态系统的功能多样性与其相关的生物多样性联系起来提供可靠的基础，并以金丝藻的种类分布格局和生态生理生态位宽度为例。

Distribution pattern of organisms, the links between the organisms ecology and their distribution pattern as well as the generalizability of such pattern are a crucial basis for assessing the dynamic nature of ecosystems and their associated biodiversity. The interplay between biodiversity and ecosystem functions raises the question of how the functional differentiation between taxa is related to their distribution pattern. One of the most obvious functional differentiations is that of nutritional strategies, i.e. heterotrophic versus mixotrophic versus phototrophic. Ideal targets for addressing such overarching research questions are microbial eukaryotes due to their overwhelming diversity and functional differentiation. The chrysomonads (chrysophytes) are a particularly well suited model group as they are widespread and among the dominant flagellates in a wide range of habitats, a wide range of nutritional strategies is realized within this group and chrysomonads with different strategies typically co-exist in many different habitats. Further, they are comparatively well investigated and members of this group have a long tradition as protist model species in ecology and ecophysiology. Heterotrophy evolved several times independently within the chrysomonads. Here we hypothesize that, in general, heterotrophic taxa may tolerate a wider range of physicochemical conditions as compared to mixotrophic and phototrophic taxa. Further we hypothesize that, in consequence, the distribution pattern of chrysomonad taxa differ between phototophic, mixotrophic and heterotrophic taxa, i.e. correlate with their ecology rather than with their phylogeny. In a first working package we will characterize chrysomonad growth rates as a function of food and nutrient concentration, food quality and light intensity as a basis for comparative analyses of the niche width of heterotrophic and phototrophic strains. In a subsequent working package we will test the assumption that the fundamental niche width systematically differs between heterotrophic, mixotrophic and phototrophic chrysophyte lineages. We complement these ecophysiological analyses with field surveys focusing on the regional distribution pattern with respect to habitat characteristics. We specifically hypothesize that distribution pattern of phototrophic chrysomonads are more restricted to habitats of similar abiotic conditions as are those of heterotrophic chrysomonads and that seasonality is more pronounced in phototrophic chrysomonads as compared to heterotrophic chrysophytes. In sum, this study will provide a sound basis for linking the functional diversity of ecosystems with their associated biodiversity exemplified for species distribution pattern and ecophysiological niche widths of chrysomonads.