Morphology: how does it vary and what does it reveal about evolution? Ontogenetic and phylogenetic variation in extant brachiopod crura and loops

形态学？它是如何变化的，它揭示了进化的什么？现存腕足动物脚和环的个体发育和系统发育变异摘要生物体的形状是生物体潜在的遗传组成与环境相互作用的媒介。 只有通过研究形状以及形状如何变化以及为什么变化，进化生物学家才能开始理解潜在的基因/环境相互作用的产物。 由于形状是灭绝（不再生存）生物可遗传信息的主要来源，因此古生物学家假设形状变异的边界与进化枝（进化实体）密切对应，正如基于等级的分类群层次所暗示的那样。 这一假设很少得到验证。 该研究项目将测试现存腕足动物中公认的分类群的分支地位，腕足动物是5亿多年来在多样性和丰度方面最具古生物学意义的后生动物群之一。 大约95%的物种已经灭绝; 5%的rhynchonellide和terebratulide腕足动物物种现存（仍然活着），我们有一个难得的机会（1）在不同的层次水平上测试分子和形态的同源性，以前从未尝试过这个分支;（2）比较功能上重要的特征的大小和形状，主要是称为脚和环的特征，（3）利用这些信息对足和环中的成体和生长阶段进行定量比较，并将生长转变置于由形状和分子所告知的进化背景中。如果古生物学家不能可靠地区分进化信息和明显误导的形状变化，那么从观察到的变化中得出的进化解释从根本上是不可检验的。这项研究的结果对生活腕足动物可以有深远的影响，宏观进化的解释来自任何组灭绝后生动物的分类数据，在揭示相关的问题，不加批判地接受未经检验的假设同源性（共享共同祖先的功能）。将进行分析的代表性物种的所有生活rhynchonellide和terebratulidine属，所有生活terebratellidine属的分子序列已提供，使用简约和贝叶斯分析。 在脚和环的生长变化将量化使用的3D图像从microCT扫描的钙质lophophophophore支持在活腕足动物的几何形状分析。 在脚和环发展的增长特征极性将比较系统发育极性使用外群分析。 树比较方法将被用来评估定性和定量形态特征分布的模式，并比较分子和形态分析的结果。 还将进行总证据分析，并与仅从形态学和仅从分子序列数据得出的结果进行比较。 虽然腕足动物这个词不是一个家喻户晓的词，就像蛤或蜗牛一样，腕足动物提供了一个很好的机会来研究生命周期和谱系的形态变化，化石记录中保存了巨大的灭绝多样性，以及今天生活的较小，更易于管理的多样性。 该研究项目将通过加州大学戴维斯分校的进化生物学和古生物学课程为本科生和研究生的教育做出贡献，并将支持女研究生和女博士后研究员的培训和指导。 我们将利用机会在野餐日（加州大学戴维斯分校校园范围内的年度开放日）和探索科学中心（戴维斯市）与公众分享我们的研究成果。 腕足动物的三维图像将完全可以在一个网站上访问，该网站旨在分享我们研究的视觉结果。我们开始对脊椎动物形态的发展和进化有了更深入的了解，但我们对更多样化的海洋无脊椎动物的进化形态的理解却远远落后。 我们的研究将努力向公众介绍和解释一组海洋无脊椎动物的迷人古生物学复杂性的一部分，并让公众参与关于进化性质的讨论：识别，表征和解释随时间的变化。

Morphology? how does it vary and what does it reveal about evolution? Ontogenetic and phylogenetic variation in extant brachiopod crura and loopsAbstract Organism shape is the medium through which the underlying genetic makeup of the organism interacts with the environment. Only by studying shape and how and why it varies, can evolutionary biologists begin to understand the product of underlying genes/environment interaction. Because shape is the primary source of heritable information from extinct (no longer living) organisms, paleontologists assume that the boundaries of shape variation correspond closely to clades (evolutionary entities), as implied by the hierarchy of rank-based taxa. This assumption is seldom tested. This research project will test the clade status of taxa recognized in extant Brachiopoda, one of the most paleontologically significant metazoan groups in terms of diversity and abundance for over half a billion years. Roughly 95% of species are extinct; with the 5% of rhynchonellide and terebratulide brachiopod species extant (still living), we have a rare opportunity (1) to test molecular and morphological phylogenies at different hierarchical levels, never before attempted for this clade; (2) to compare the size and shape of functionally significant features, primarily features called crura and loops, among adults within and among species, and across growth stages; (3) to use this information to produce quantitative comparisons among adults and growth stages in crura and loops, and place the growth transformations in an evolutionary context informed by both shape and molecules. If paleontologists cannot reliably distinguish evolutionarily informative from significantly misleading shape variation, evolutionary interpretations drawn from the observed variation are fundamentally untestable. The results of this study on living brachiopods can have profound implications for macroevolutionary interpretations derived from taxonomic data on any group of extinct metazoans, in revealing problems associated with uncritically accepting untested assumptions of homology (shared common ancestry of features). Analyses will be conducted on representative species of all living rhynchonellide and terebratulidine genera, and all lving terebratellidine genera for which molecular sequences have been made available, using parsimony and Bayesian analysis. Growth variation in crura and loops will be quantified using geometric shape analysis on 3D images obtained from microCT scans of calcareous lophophore supports in living brachiopods. Growth character polarity in crural and loop development will be compared with phylogenetic polarity using outgroup analysis. Tree comparison methods will be utilized to evaluate patterns of qualitative and quantitative morphological character distribution, and to compare results from molecular and morphological analyses. Total evidence analyses will also be conducted and compared with those derived from morphology alone and molecular sequence data alone. Although the word brachiopod is not a household word, as is clam or snail, brachiopods provide an excellent opportunity to study changes in morphology over lifespans and lineages, with enormous extinct diversity preserved in the fossil record and a smaller, more manageable diversity living today. This research project will contribute to the education of undergraduate and graduate students through coursework in evolutionary biology and paleontology at UC Davis, and will support the training and mentoring of a female graduate student and female post-doctoral researcher. We will take advantage of opportunities to share our research results with the public at Picnic Day (a UC Davis campus-wide annual open house) and the Explorit Science Center (City of Davis). Three-dimensional images of brachiopods will be fully accessible on a website created to share the visual results of our research. We are beginning to develop a more sophisticated understanding of the development and evolution of morphology in vertebrate animals, yet our understanding of evolutionary morphology across a much more diverse array of marine invertebrate animals lags well behind. Our research will strive to introduce and explain a portion of the fascinating paleobiological complexity of one group of marine invertebrates to the general public, and engage the public in discussions about the nature of evolution: recognizing, characterizing, and interpreting change over time.