Evolution and Environment of Tropical American Cupuladriid Bryozoa

热带美洲杯状苔藓动物的进化和环境斯克里普斯海洋研究所杰里米·杰克逊EAR-0345471 PI将决定加勒比海重大环境变化在多大程度上驱动了过去1500万年来杯状苔藓动物的宏观进化模式。库普拉德里亚科是一种小型的、自由生活的殖民地动物，其骨骼是热带美洲最丰富、保存最完好的化石之一。它们的生活史差异很大，从完全有性的物种到几乎完全无性的物种，这些差异在殖民地的萌芽模式和形状中得到了很好的保存。丘布拉德里虫还通过它们被称为动物园的模块生活室大小的季节性变化来记录环境中平均年温度和总生产力的变化。因此，我们有机会从相同的化石中准确地观察到重大的进化和环境变化。初步工作表明，加勒比海与热带东太平洋非常相似，直到大约1000万年前，大西洋和太平洋之间通过巴拿马海峡仍存在强烈的海洋混合。当时，两个大洋都出现了季节性上升流、温度波动和高生物生产力。然后，随着地峡的上升和海洋之间联系的减少，加勒比海慢慢变得更加稳定，几乎没有上升流，季节变化和生产力也很低。也有证据表明，杯状苔藓虫从主要的无性繁殖和碟状苔藓属的优势，转变为以有性生殖和杯状苔藓属的优势--今天在东太平洋和加勒比海之间观察到的情况。PIS将利用空间和时间上丰富的、重复的收藏来测试所有这些模式，以非常详细地记录环境条件的变化以及苔藓虫生活史和分类组成的相应变化。通过使用相同的样本来衡量环境和生物变化，他们将能够以很高的统计置信度重建进化和环境之间的关系，从而避免了困扰早期此类性质研究的粗略方法和缺乏精确度。

ABSTRACTEvolution and Environment of Tropical American Cupuladriid BryozoaJeremy Jackson, Scripps Institute of OceanographyEAR-0345471PIs will determine the extent to which major environmental change in the Caribbean Sea has driven the macroevolutionary patterns of cupuladriid bryozoans over the past 15 million years. Cupuladriids are small, free-living colonial animals whose skeletons are among the most abundant and well-preserved fossils from tropical America. They vary greatly in their life histories, from entirely sexual to almost exclusively asexual species, and these differences are well preserved in the budding patterns and shapes of colonies. Cupuladriids also record changes in the mean annual range of temperature and total productivity in the environment through seasonal variations in size of their modular living chambers called zooids. Thus we have the opportunity to precisely observe major evolutionary and environmental changes from the same fossils. Preliminary work suggests that the Caribbean closely resembled the tropical eastern Pacific until about 10 million years ago when there was still strong oceanographic mixing between the Atlantic and Pacific through the Panamanian Strait. At that time, seasonal upwelling, temperature fluctuations, and high biological productivity occurred in both oceans. Then, as the Isthmus rose and connections between the oceans diminished, the Caribbean slowly became more stable with little upwelling and low seasonal variations and productivity. There is also evidence that the cupuladriid bryozoans shifted from predominantly asexual reproduction and dominance of the genus Discoporella to predominantly sexual reproduction and dominance by the genus Cupuladria - conditions that are observed between the eastern Pacific and Caribbean today. PIs will test all these patterns using abundant, replicate collections in both space and time to document in great detail the changes in environmental conditions and corresponding changes in bryozoan life histories and taxonomic composition. By using the same samples for measures of both environment and biological change they will be able to reconstruct the relations between evolution and environment with high statistical confidence, thereby avoiding the broad-brush approach and lack of precision that have plagued earlier studies of this nature.