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

本研究旨在探讨Baltoscandia地区奥陶纪苔藓虫的空间分异格局。生物多样性大事件（GOBE）是继寒武纪大爆发之后，中生代生物多样性的第二次脉动。该项目的主要目的是确定空间多样性在多样化过程中的作用。这项研究将回答的问题，在哪一级的生物多样性发生，哪些生态参数驱动它，以及有多强的影响是省籍和移民的生物多样性。苔藓动物是研究奥陶纪生物多样性模式的理想模式类群，因为它们具有许多优点，包括在大多数分支中具有钙化的骨架，它们的模块化组织（严格的殖民地），广泛分布于奥陶纪的海洋生物区。它们占据了波罗的海大陆架，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，这肯定会影响底栖动物的多样性动态，其中包括苔藓虫。苔藓动物的快速生物多样性和波罗的海古地理变迁的结合是研究苔藓动物时空多样性格局的有利条件。多样性研究（α-，β-，γ-）将集中在两个时空断面：1）挪威，瑞典，爱沙尼亚和俄罗斯西北部的Darriwilian，2）挪威，瑞典，爱沙尼亚和俄罗斯西北部的Katian。此外，将研究Baltoscandia的奥陶纪苔藓虫动物群的古生物地理模式，以估计迁移在生物多样化过程中的作用。在预定的研究过程中，将对几个假设进行检验。首先，据推测，生物多样性是强大的，在当地规模和隔离发挥了重要作用。其次，某些生态因素，如底质类型，深度，沉积物流入，并可能营养支持影响苔藓虫的生物多样性在奥陶纪。第三，大规模的移民明显抑制了生物多样性，导致α多样性（本地）的增加，但β多样性（区域间）的减少，而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将增加，而在大规模灭绝期间，全球多样性的各个部分（α、β或γ）都将受到影响。

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.