Causes and consequences of genome size diversity in animals

动物的基因组大小在7000倍之间，这一观察结果在超过65年的时间里一直是遗传学的中心谜题。我的实验室处于研究的前沿，试图对动物基因组大小多样性的模式进行分类和解释。在我的实验室未来5年的研究将集中在三个互补的领域：1)几个目标群体中不同物种的基因组大小多样性的模式和相关性；2)DNA含量的组织特异性调节(内源多倍体)；以及3)基因组大小变化和转座元件进化的机制。在第一组研究中，我和我的学生将利用我们丰富的专业知识来极大地扩展我们对软体动物和蜘蛛类基因组大小多样性的知识，并将提供第一个关于地衣基因组大小的研究。这将包括广泛的、基于发现的探索，以及使用系统发育信息比较方法对假说进行重点测试。在第二系列项目中，我们将研究内源多倍体的生物学意义，即基因组在特定组织中复制数千次。内源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中研究内多倍体的模式，以便测试关于这种现象的生物学相关性的想法：1)蜘蛛的丝腺和毒腺具有不同的取食策略(例如，编网和主动狩猎)；2)一些昆虫的卵巢中发现的哺乳细胞(滋养细胞)，为发育中的卵提供营养；3)不同食性昆虫的肠道和马氏管。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，特别是转座元件在影响总基因组大小中所起的作用。这一研究领域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的可变性相关。这里提出的研究将为培训一些硕士、博士和本科生提供机会，并预计将产生很大的影响，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.**