Evolution of Novel Ontogenies

Raff9982644这个项目的目标是了解发展演变的机制，以及发展过程本身如何影响或限制进化的方向。 将使用两种密切相关但具有高度不同的早期发育模式的海胆。 Heliocidaris tuberculata通过摄食幼虫以祖先的间接模式发育，而Heloicidaris erythrogramma直接从胚胎发育到幼年成虫。 该项目将确定两个物种之间发育差异的基因，定义它们的表达模式，并测试它们在产生进化改变的发育模式中的作用。 理解基因表达变化在早期发育进化中的潜在作用的关键来自最近两个物种之间的跨物种杂交。 尽管亲种的发育方式不同，但卵的发育方式不同。erythrogramma由H. tuberculata精子通过新的途径发育，其中通过来自父本基因组的显性因子的作用恢复了许多原始pluteus特征。 杂交将用于研究新的幼虫特征是如何产生的，并分离调控幼虫特征发育的基因。 具体目的是：（1）确定细胞谱系示踪染料的方向。 将使用组织特异性基因标记研究表达区域的转化，并在转化细胞谱系的背景下进行定义。 (2)将确定作为在进化中修改或丢失的幼虫特征的调节因子的候选者而分离的基因的表达模式。 (3)通过在H.红带胚 (4)基因表达的显性抑制也将用于研究候选基因的作用。 可以预测特定的表型，从而解释这些实验的结果。 该项目的结果将提供一个深入了解的基因机制，基础上的进化修改的发展过程中，并进入的作用，限制发展过程的演变。

Raff9982644The goal of this project is to understand the mechanisms by which development evolves, and how developmental processes themselves influence or constrain the direction of evolution. Two species of sea urchins that are closely related but have highly different modes of early development will be used. Heliocidaris tuberculata develops in the ancestral indirect mode via a feeding larva, whereas Heloicidaris erythrogramma develops directly from embryo to juvenile adult. The project will identify genes that underlie developmental differences between the two species, define their expression patterns, and test their roles in producing an evolutionarily changed mode of development. The key to understanding the prospective role of gene expression changes in the evolution of early development comes from the recent creation of cross-species hybrids between the two species. Despite the different modes of development of the parent species, eggs of H. erythrogramma fertilized by H. tuberculata sperm develop via novel pathway in which a number of the primitive pluteus features are restored by the action of dominant factors derived from the paternal genome. Hybrids will be used to study how new larval features are generated, anad to isolate genes that regulate development of larval features. The specific aims are to (1) Determine the direction of cell lineage tracer dyes. Transformations of expression territories will be investigated using tissue-specific gene markers, and defined within the context of transformed cell lineages. (2) The expression patterns of genes isolated as candidates for the regulators of larval features modified or lost in evolution will be determined. (3) The function of genes implicated in appearance of larval features will be tested by over/ectopic expression experiments in the H. erythrogramma embryo. (4) Dominant inhibition of gene expression will also be used to study the roles of candidate genes. Specific phenotypes can be predicted, and thus the results of these experiments interpreted. The results of this project will provide an insight into the genic mechanisms that underlie evolutionary modifications of developmental processes, and into the role of constraints in the evolution of developmental process.