Developmental Modules & Evolvability: The Gastropod Foregut as a Model

发展模块

• 批准号: RGPIN-2015-06484
• 负责人: Page, Louise
• 金额: $ 2.19万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683428
• 关键词: Developmental; Modules; Evolvability; Gastropod; Foregut

Why have some groups of organisms diversified explosively since their first appearance, while others have puttered along for millions of years without much change at all? This mystery is a core issue for the emerging field of Evolutionary Developmental Biology, which is dissatisfied with the traditional view that natural selection acting on random, genetically-specified variation among offspring provides the complete story about how species evolve. Although selection is clearly important, evolutionary developmental biologists emphasize that transfer of information from genotype to phenotype occurs via the process of development and developmental organization can influence the amount and kind of variation produced as raw material for selection. The prevailing hypothesis suggests that the greatest amount of `evolvability' will be found among developmental systems organized into semi-autonomous modules that can spin off variant phenotypes without disrupting the developmental integrity of whole complex structures. This hypothesis is conceptually appealing but its validity depends on finding systems in which a link between high rates of evolution and a modular organization of development can be demonstrated.***My students and I have identified a promising model system for investigating the relationship between evolvability and developmental modules. We study the developing foregut in gastropods (snails), which are diverse and abundant within Canada's rich resources in marine biodiversity, although tropical species will also be included in our research. The research will test the following hypotheses: 1) differences in time of development for two foregut modules helped facilitate the evolution of feeding from non-feeding larvae early in the evolutionary history of gastropods, which in turn had a profound effect on extinction and speciation rates, 2) a physical dissociation between two foregut developmental modules has facilitated high capacity for evolvability in a large group of predatory snails, which will be tested by characterizing development in a second group of snails that may have independently evolved this key developmental innovation, and 3) one of the foregut modules may have been co-opted and re-purposed to allow encapsulated embryos to feed on nurse eggs, which may have ultimately allowed encapsulated embryos that have lost free-swimming larvae from their life history to subsequently re-evolve into swimming larvae that feed on microalgae within the water column. This research will provide valuable training opportunities for students in contemporary methods of morphological analysis, while encouraging them to extend the conceptual boundaries of an exciting new view of evolution.**

为什么一些生物体自第一次露面以来就会爆炸性地散发出来，而另一些生物体已经推动了数百万年，但根本没有改变？这个谜团是进化发展生物学新兴领域的核心问题，它对传统的观点不满意，即自然选择在后代中随机，遗传指定的变化作用，提供了有关物种如何进化的完整故事。尽管选择显然很重要，但进化发展生物学家强调，通过发展和发展组织的过程，信息从基因型到表型的转移可能会影响作为选择的原材料产生的变异数量和种类。流行的假设表明，在组织为半自主模块中的发育系统中，最大量的“可发展性”将发现，这些模块可以旋转变体表型而不会破坏整个复杂结构的发育完整性。该假设在概念上具有吸引力，但其有效性取决于找到系统，在这些系统中，可以证明高进化率与模块化的发展组织之间的联系。我们研究了加拿大海洋生物多样性丰富资源中多种多样且丰富的腹足动物（蜗牛）发展中的发展，尽管热带物种也将包括在我们的研究中。这项研究将检验以下假设：1）两个前述模块的发展时间差异有助于促进胃足动物进化史的早期，从非喂养幼虫中喂养的演变，这反过来又对灭绝和形成率产生了深远的影响，2）在巨大的范围内，养成了较大的范围，以实现较大的范围，以实现较大的范围，以实现较大的范围，以实现较大的范围，以实现一种远景，以使能力依赖于侵蚀量的范围。通过表征在第二组蜗牛中进行的发展测试，这些蜗牛可能独立发展了这一关键的发展创新，3）可能已经选择并重新拨出了一个前述模块，以允许胚胎喂食护士卵，这些胚胎可能最终允许封装的胚胎，这些胚胎从他们的胚胎中却失去了自由的胚胎，以使其流失了，从而使人们的往来远处是富裕的寿命，以使其远程循环延伸，以使其远程循环延伸，以使其陷入困境的历史悠久的历史悠久的历史记录 - 水柱中的微藻。这项研究将为学生提供当代的形态分析方法的宝贵培训机会，同时鼓励他们扩大令人兴奋的新观点的概念界限。**