From high latitudes into the tropics: The role of palaeogeography for the biodiversification of Ordovician bryozoans of Baltoscandia

本研究旨在研究巴尔托斯坎迪亚奥陶纪苔藓虫的空间多样性格局。继寒武纪大爆发之后，大生物多样性事件是显生宙生物多样性的第二次高潮。预期的研究将有助于揭示GOBE期间生物多样化过程的新见解。该项目的中心目标是确定空间多样性在多样性中的作用。本研究将回答生物多样性发生在哪个水平，哪些生态参数驱动生物多样性，省际和移民对生物多样性的影响有多强等问题。苔藓虫是研究奥陶纪生物多样性模式的理想模型类群，因为它们具有许多优势，包括大多数分支具有钙化骨架，它们的模块化组织（严格的殖民地），在奥陶纪海洋生物群落中分布广泛。它们占据了波罗的海的大陆架，这是一个在奥陶纪从高纬度向热带移动的古大陆。这种漂移导致了逐渐的气候变化，这当然影响了底栖动物的多样性动态，其中包括苔藓虫。苔藓虫的快速生物多样性与波罗的海古地理变化相结合，为研究其时空多样性格局提供了有利条件。多样性（α -, β -, γ -）的研究将集中在两个时空样带上：1)挪威、瑞典、爱沙尼亚和俄罗斯西北部的达里威廉，以及2)挪威、瑞典、爱沙尼亚和俄罗斯西北部的卡蒂安。此外，还将研究巴尔托斯坎迪亚奥陶纪苔藓动物的古生物地理格局，以估计迁徙在生物多样化过程中的作用。在预期的研究过程中，几个假设将被检验。首先，在局部尺度上，生物多样性较强，隔离性起了重要作用。其次，基质类型、深度、沉积物流入以及可能的营养支持等生态因素影响了奥陶纪苔藓虫的生物多样性。③大规模迁移对生物多样性有明显的抑制作用，α多样性（局部）增加，β多样性（区域间）减少，γ多样性（区域）保持不变。预计在生物多样化事件期间，多样性的所有组成部分都会增加，而在生物大灭绝期间，全球多样性的单独部分（α -、β -或γ -）会受到影响。

This proposal intends study of patterns of the spatial diversity of the Ordovician bryozoans of Baltoscandia. After the Cambrian explosion, the Great Biodiversification Event (GOBE) was the second pulse of diversification of the life in the Phanerozoic. The intended study will help to reveal new insights in the processes of biodiversification during the GOBE.The central aim of the project is to identify the role of spatial diversity in the diversification. This study will answer the questions, at which level the biodiversification takes place, which ecological parameters drive it, and how strong is the influence of provinciality and migrations on the biodiversification. Bryozoans are a perfect model group for study of diversity patterns in the Ordovician because they have many advantages including possessing of calcified skeleton in the majority of clades, their modular organisation (strictly colonial), wide distribution in marine biotopes of the Ordovician. They occupied the shelves of Baltica, a palaeocontinent moved from high latitudes towards the tropics during the Ordovician. This drift resulted in a gradual climatic change which certainly affected the diversity dynamics of the benthic fauna, among them bryozoans. The combination of the fast biodiversification of bryozoans and the palaeogeographical shift of Baltica is the beneficial condition to study the temporal and spatial diversity patterns. The study of diversity (alpha-, beta-, gamma-) will be concentrated in two temporal/spatial transects: 1) Darriwilian of Norway, Sweden, Estonia, and NW Russia, and 2) Katian of Norway, Sweden, Estonia, and NW Russia. In addition, palaeobiogeographic patterns of Ordovician bryozoan faunas of Baltoscandia will be studied, in order to estimate the role for migrations in biodiversification processes. In the course of the intended study several hypotheses will be tested. Firstly, it is supposed that biodiversification was strong at the local scale, and isolation played an important role. Secondly, certain ecological factors as substrate type, depth, sediment influx, and probably nutrient support influenced the biodiversification of bryozoans in the Ordovician. Thirdly, large-scaled migration apparently suppressed the biodiversification resulting in the increase of the alpha-diversity (local) but decrease of the beta-diversity (interregional), whereas gamma-diversity (regional) remains without changes. It is expected that the all components of diversity increase during biodiversification events, whereas during mass extinctions separate parts of the global diversity (alpha-, beta-, or gamma-) are affected.