Arrival of the fittest: examining the underlying mechanisms of morphological plasticity in an adaptive radiation

关键词：进化，可塑性，基因表达，骨骼摘要：表型可塑性目前在进化生物学中引起了激烈的争论。这场辩论涉及环境因素在产生生物多样性、物种和最终标准达尔文综合（或其延伸）的效用中的作用。虽然可塑性是一个与环境变化越来越相关的实证研究的主题，但我们仍然缺乏对进化系统中可塑性潜在机制的一般理解。该研究将利用骨生物学的知识来填补这一空白，特别是关注骨骼如何解释指导其生长和产生适应性变化的机械感觉刺激。骨生物学的一个中心教条是骨细胞（机械感觉细胞）是骨对机械应力作出反应的唯一机制。然而，并不是所有有骨的动物都有骨细胞（大多数鱼类已经失去了骨细胞），我们的初步数据表明，有一些新兴的替代方法。具体地说，我们之前的研究已经确定了非洲慈鲷相关物种之间骨可塑性程度的差异。慈鲷是进化生物学家的一个典型系统，因为它们来自最近的共同祖先，但表现出大量的适应性骨骼变异。这种变异似乎是由共同遗传背景上的一些突变控制的。到目前为止，我们已经将可塑性实验与QTL定位方法结合起来，在颅面骨骼中确定了许多候选的“可塑性基因”。这些基因包括先前与骨发育有关的信号通路成员（wnt, bmp, FGFs），以及包括根蛋白在内的结构基因——根蛋白是初级纤毛的关键成分，代表了机械感觉功能的潜在替代机制。这些发现为理解可塑性的分子和细胞机制及其对进化的贡献提供了坚实的基础。

Studentship strategic priority area: BiodiversityKeywords: Evolution, plasticity, gene expression, boneAbstract: Phenotypic plasticity currently drives contentious debate in evolutionary biology. This debate deals with the role of environmental cues in generating biodiversity, species, and ultimately the utility of the standard Darwinian synthesis (or its extension). While plasticity is a topic of much empirical research with growing relevance to environmental change, we still lack a general understanding of the underlying mechanisms of plasticity in evolutionary systems. This studentship will draw on knowledge from bone biology to fill this gap, specifically focusing on how bones interpret the mechanosensory stimuli that instruct their growth and produce adaptive variation. A central dogma in bone biology is that osteocytes (mechanosensory cells) are the sole mechanism for bone to respond to mechanical stress. However, not all animals with bones possess osteocytes (most fishes having lost them), and there are emerging alternatives which our preliminary data point toward. Specifically, our previous research has identified variation in the magnitude of bone plasticity between related species of African cichlids. Cichlids are an exemplary system for evolutionary biologists in that they are derived from a recent common ancestor but exhibit vast amounts of adaptive skeletal variation. This variation appears to be controlled by a few mutations on a common genetic background. So far we have combined plasticity experiments with QTL mapping approaches to identify a number of candidate 'plasticity genes' in the craniofacial skeleton. These genes include members of signalling pathways previously implicated in bone development (Wnts, BMPs, FGFs), and structural genes including rootletin - a key component of the primary cilia and representative of a potential alternative mechanism for mechanosensory function. These findings provide a strong basis for understanding the molecular and cellular mechanisms involved in plasticity and their contribution to evolution.