Causes and consequences of genome size diversity in animals

动物基因组的大小是人类基因组的70到7000倍，这一发现在超过65年的时间里一直是遗传学的核心谜题。我的实验室处于研究的前沿，致力于编目和解释动物基因组大小多样性的模式。未来5年，我的实验室将专注于三个互补的领域：1)几个目标群体中物种基因组大小多样性的模式和相关关系；2) DNA含量的组织特异性调节（内多倍体）；3)基因组大小变化和转座因子进化的机制。在第一组研究中，我和我的学生将利用我们相当多的专业知识，极大地扩展我们对软体动物和蛛形纲动物基因组大小多样性的了解，并将提供地衣基因组大小的第一个研究。这将包括广泛的，基于发现的探索和使用系统发育信息比较方法的假设的集中测试。在第二个系列项目中，我们将研究内多倍体的生物学意义，其中基因组在特定组织中复制多达数千次。内多倍体似乎是一种非常普遍的现象，但其总体意义仍然知之甚少。我们将在节肢动物的三个主要案例研究中检查内多倍体的模式，以测试关于这种现象的生物学相关性的想法：1)具有不同摄食策略（例如，织网与主动狩猎）的蜘蛛的丝腺和毒腺；2)哺乳细胞（滋养细胞）存在于某些昆虫的卵巢中，为发育中的卵提供营养；3)不同食性昆虫的肠道和马尔比氏小管。最后，在第三组项目中，我们将继续扩大我们对基因组大小变化的机制基础的研究，特别是转座因子在影响总基因组大小方面所起的作用。该领域的研究使用生物信息学分析和使用下一代测序技术的调查测序来确定转座元件的丰度、多样性和活性如何与基因组大小变异性相关。这里提出的研究将为许多硕士、博士和本科生的培训提供机会，并预计将具有很高的影响力，因为它解决了对我们理解基因组形式、功能和进化至关重要的问题。**

The genomes of animals range >7,000-fold in size, an observation that has remained a central puzzle in genetics for more than 65 years. My lab is at the forefront of research that seeks to catalogue and explain the patterns of genome size diversity across animals. The next 5 years of research in my lab will focus on three complementary areas: 1) Patterns and correlates of genome size diversity across species in several target groups; 2) Tissue-specific modulations of DNA content (endopolyploidy), and 3) Mechanisms of genome size change and transposable element evolution. In the first set of studies, my students and I will use our considerable expertise to greatly expand our knowledge of genome size diversity in molluscs and arachnids, and will provide the very first study of genome sizes in lichens. This will include both broad, discovery-based explorations and focused testing of hypotheses using phylogenetically-informed comparative methods. In the second series of projects, we will investigate the biological significance of endopolyploidy, in which the genome is replicated up to thousands of times within specific tissues. Endopolyploidy appears to be a very widespread phenomenon, but its overall significance remains poorly understood. We will examine the patterns of endopolyploidy in three major case studies from arthropods in order to test ideas regarding the biological relevance of this phenomenon: 1) Silk and venom glands of spiders with varying feeding strategies (e.g., web-weaving vs. active hunting); 2) Nurse cells (trophocytes) found in the ovaries of some insects, which provision the developing eggs with nutrients; and 3) Guts and Malpighian tubules in insects with different diets. Finally, in the third set of projects, we will continue to expand our investigations of the mechanistic bases of genome size change, in particular the role played by transposable elements in affecting total genome size. This area of research uses bioinformatics analyses and survey sequencing using next-generation sequencing technology to determine how transposable element abundance, diversity, and activity are related to genome size variability. The research proposed here will provide opportunities for the training of a number of MSc, PhD, and undergraduate research students, and is expected to be of high impact as it addresses questions of fundamental importance for our understanding of genome form, function, and evolution.**