Transformations in the evolution of Peracarida (Crustacea)

甲壳纲是一种高度多样化且具有重要生态意义的甲壳类动物。在形态上，有袋目动物的特点是雌性的孵化和后部胚胎化的幼虫/幼崽。然而，它们的单系性在分子系统发育研究中一再受到质疑，它们之间的内在关系尚未达成共识。有袋动物内部的进化具有深远的微观和宏观进化意义。与许多其他主要的海洋分类群相比，Peracarida缺乏专门的分散阶段，这增加了种群的碎片化，并且Peracarida从繁殖策略r转向了繁殖策略k。如前所述，通过改变有效种群大小，这对它们的分子进化速度有长期影响。袋类动物的进化也对袋类动物的运动产生了影响，这反映在pleon的形态上。栖息地之间的变化（如淡水、陆地或浅水海洋和深海）可能对分子进化的速度有类似的长期影响。假设/研究问题/目标：我们的主要目标是：通过（形态学+分子）结合的方法，解决跨足纲的内部关系，并测试它们的单系性。了解运动器官（胸足类和胸腹类）在有袋类动物进化过程中的进化转变。确定与等足目动物的繁殖策略或栖息地之间的转换有关的分子进化速率的长期变化。途径/方法：我们将结合现代形态学（μCT， cLSM和组织学）和基因组学（转录组测序和靶标捕获）方法，研究多达240种物种（取决于方法）。这将允许迄今为止最详细的Peracarida进化史重建，以及追踪关键形态转变和识别分子取代率的长期变化（包括蛋白质编码位点和非编码位点之间以及同义和非同义替换之间的比较）。这项研究将在罗斯托克（德国）和维也纳（奥地利）进行。原创性/创新水平：这将是第一个结合形态学和系统基因组分析来解决Peracarida内部关系的项目。一个特别的新奇之处在于，除了解决系统发育关系外，还使用了大量的基因组数据集来深入了解基因组进化过程。后者不仅对Peracarida很重要，而且将有助于更好地理解生命史变化对一般分子进化速率的长期影响。

Peracarida is a highly diverse and ecologically important group of malacostracan crustaceans. Morphologically, Peracarida is well characterized by a marsupium in which female’s hatch and rear embryonized larvae/juveniles. However, their monophyly was repeatedly questioned in molecular phylogenetic studies and no consensus has been reached regarding their internal relationships. The evolution of the intra-marsupial development had far reaching micro- and macroevolutionary consequences. In contrast to many other predominantly marine taxa, Peracarida lacks a dedicated dispersal stage, which increases population fragmentation, and Peracarida shifted from a reproductive r-strategy to a k-strategy. By altering the effective population size, this has long-term consequences for their rate of molecular evolution, as previously observed. The evolution of the marsupium also had consequences for the locomotion of peracarids, which is reflected in the morphology of the pleon. Shifts between habitats (like freshwater, terrestrial, or shallow-water marine and deep sea) might have similar long-term effects on the rate of molecular evlution. Hypotheses / research questions / objectives: Our key objectives are: Resolve the internal relationships within Peracarida and test their monophyly in a combined (morphological + molecular) approach. Understand the evolutionary transformation of the locomotory apparatus (thoracopods and pleon) in Peracarida as a result of the evolution of the marsupium. Identify long-term changes in the rate of molecular evolution in relation to the reproductive strategy or transitions between habitats in Isopoda. Approach / methods: We will combine modern morphological (μCT, cLSM and histology) and genomic (transcriptome sequencing and target capture) methods and will study up to 240 species (depending on the method). This will allow the most detailed reconstruction of the evolutionary history of Peracarida to date as well as tracing key morphological transitions and identifying long-term changes in the molecular substitution rate (including comparisons between protein-coding and non-coding loci and between synonymous and non-synonymous substitutions). The research will be conducted in Rostock (Germany) and Vienna (Austria). Level of originality / innovation: This will be the first project to combine morphological and phylogenomic analyses to resolve the relationships within Peracarida. A particular novelty is the usage of the vast genomic data sets to gain insights into genome evolutionary processes in addition to resolving the phylogenetic relationships. The latter will be of importance not only for Peracarida, but will help to better understand the long-term effects of life-history changes on rates of molecular evolution in general.