Test for Evolution Without Sex in Bbeloid Rotifers

性重组和突变提供了基因可变的原材料，在更高、更复杂的生物体中，进化力量在这些原材料上发挥作用。因此，基于这一假设，性被认为是进化过程中一个重要的、几乎是必要的组成部分。然而，哈佛大学的Matthew Meselson博士描述了一类动物，Bdelloidae，到目前为止，已经确定这种动物没有性别基因交换。但是，正如他指出的那样，性交换可能在罕见或至少是未知的情况下发生，需要更严格的测试来证实这样一个事实，即一个在进化中取得成功的有机体缺乏任何基因交换的机制。他建议使用限制性片段长度多态(RFLP)作为测试。瓢虫总科的特定物种，被认为是二倍体，将被选为测试生物。分离的DNA将用限制性内切酶进行片断，并将确定杂合性的程度。潜在的假设是有性有机体比无性有机体更快地将其染色体纯合。该项目可以在一年的期限内完成，而且风险很高，因为如果答案是轮虫DNA中几乎没有杂合性，那么这些生物体可能具有某种类型的性机制，因此，对进一步研究没有什么兴趣。另一方面，如果答案是它们的DNA中有大量的杂合性，那么通过提出适当的问题，就可以对我们对进化的理解有重大的洞察。

Sexual recombination as well as mutations provides the genetically variable raw material upon which evolutionary forces act in higher, more complex organisms. Thus, based upon that assumption, sex has been considered an important, almost necessary, component of the evolutionary process. However, Dr. Matthew Meselson of Harvard University describes a class of animals, Bdelloidea, which, in so far as has been determined, has no sexual genetic exchange. But, as he points out, sexual exchange may occur under rare or at least unknown circumstances and a more rigorous test is needed to confirm the fact that an organism which has been successful in evolution is lacking any mechanism for genetic exchange. He proposes to use restriction fragment length polymorphisms (RFLP) as a test. Specific species of Bdelloidea, thought to be diploid, will be selected as test organisms. Isolated DNA will be fragmented with restriction enzymes and the extent of heterozygosity will be determined. The underlying assumption is that sexual organisms homozygous their chromosomes much more rapidly than do asexual organisms. The project can be done within the one year limitation and is high risk in that if the answer is that there is little heterozygosity seen in the rotifer DNA, the organisms probably have some type of sexual mechanism and thus, are of little interest for further study. If, on the other hand, the answer is that there is a large amount of heterozygosity in their DNA, then significant insights into our understanding of evolution can be achieved by asking the proper questions.*** //