DISSERTATION RESEARCH: Karyotypic Diversity and Species Radiation in the Genera Agrodiaetus, Lysandra and Plebicula (Lepidoptera: Lycaenidae)

哈佛大学的Naomi E. Pierce博士和Nikolai Kandul先生获得了一笔资金，用于研究染色体进化在物种辐射中的作用。核型，即细胞核中染色体的数量和结构，通常在物种之间变化不大。例如，人类有23个，而我们的近亲黑猩猩有24个。与这种普遍模式相反，在动物王国中，三种蝴蝶，即Agrodiaetus属、Lysandra属和Plebicula属，具有最大的核型多样性，在密切相关的物种中，染色体数目从7到225不等。初步研究表明，这种染色体多样性在每一个群体中都是独立进化的。皮尔斯博士和坎杜尔先生将利用这一非凡的现象来回答以下问题：这些属的核型多样化是导致新物种产生的原因，还是仅仅是促进物种形成的其他因素的副产物？什么机制促进了这些属的核型多样化？在拟进行的研究过程中：(1)利用这些属的DNA特征重构它们的进化史；(2)核型将被检查并绘制在进化树上；(3)对具有不同核型的物种进行单细胞DNA量的测定；(4)评估驱动核型多样化的因素。就其更广泛的影响而言，这项研究的结果将阐明基因组不稳定的潜在机制。这在理解医疗状况方面有实际应用；许多癌症与核型的变化有关。拟议的研究还将扩大我们对物种形成机制的认识。我们每天都读到关于物种灭绝的报道，以及自然界面临的危机。但是生态系统是两个过程的产物：物种形成，新物种的加入，以及灭绝，它们的消失。如果我们真的要解决今天的保护问题，我们需要了解等式的两边。最后，这项研究已经涉及到美国、西班牙、澳大利亚、土耳其和俄罗斯科学家之间的合作，并将继续促进国际交流和理解。

A grant has been awarded to Dr. Naomi E. Pierce and Mr. Nikolai Kandul at Harvard University to study the role of chromosomal evolution in species radiation. The karyotype, or number and structure of chromosomes in the nucleus of the cell, typically does not vary much from species to species. Humans, for example, have 23, while our closest relative, the chimpanzees, has 24. In contrast to this general pattern, three groups of butterflies, the genera Agrodiaetus, Lysandra and Plebicula, possess the greatest karyotype diversity in the animal kingdom, with chromosome numbers ranging from 7 to 225 among closely related species. Preliminary studies show that this chromosome diversity evolved independently within each of these groups. Dr. Pierce and Mr. Kandul will use this remarkable phenomenon to answer the following questions: Did karyotype diversification in these genera cause the production of new species, or is it merely the bi-product of other factors promoting speciation? What mechanisms have promoted karyotype diversification within these genera? In the course of the proposed research: (1) the evolutionary history of these genera will be reconstructed using characters from their DNA; (2) karyotypes will be examined and mapped on the evolutionary tree; (3) the amount of DNA in a single cell will be measured for species with different karyotypes; and (4) factors driving karyotype diversification will be assessed.In terms of its broader impact, the results of this research will illuminate mechanisms underlying genome instability. This has practical applications in understanding medical conditions; many cancers are correlated with changes in karyotype. The proposed research will also enlarge our knowledge of mechanisms underlying speciation. We read every day about extinction, and the crisis confronting the natural world. But ecosystems are the product of two processes: speciation, which adds new species to the mix, and extinction, which eliminates them. If we are truly to grapple with today's conservation issues, we need to understand both sides of the equation. Finally, the research has already involved collaboration between U.S., Spanish, Australian, Turkish and Russian scientists, and will continue to foster international communication and understanding.