Evolution and Environment of Tropical American Cupuladriid Bryozoa

热带美洲Cupuladriid苔藓虫的进化与环境jeremy Jackson， Scripps海洋研究所- 0345471pi将确定加勒比海在过去1500万年中主要环境变化对Cupuladriid苔藓虫宏观进化模式的影响程度。Cupuladriids是一种小型的、自由生活的殖民地动物，它们的骨骼是来自热带美洲的最丰富、保存最完好的化石之一。它们的生活史差异很大，从完全有性繁殖到几乎完全无性繁殖，这些差异很好地保存在萌芽模式和殖民地形状中。Cupuladriids还记录了平均温度的年变化范围和环境中总生产力的变化，通过它们被称为动物的模块化生活空间的大小的季节性变化。这样，我们就有机会从同一块化石上精确地观察主要的进化和环境变化。初步研究表明，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然存在强烈的海洋学混合。当时，两个海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的联系减弱，加勒比海逐渐变得更加稳定，几乎没有上升流，季节性变化和生产力也很低。也有证据表明，Cupuladria苔藓虫从主要的无性繁殖和Discoporella属的优势转变为主要的有性繁殖和Cupuladria属的优势-今天在东太平洋和加勒比海之间观察到这种情况。pi将在空间和时间上使用大量的复制收集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测量环境和生物变化，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，从而避免了在这一性质的早期研究中困扰的粗放式方法和缺乏精度。

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.