ROA: Evolutionary Dynamics of Speciation by Polploidy in Treefrogs

高等动物中的多倍体一般很少见，但已经发现了五个不同科的15种以上的青蛙和蟾蜍。这项研究的对象是两种广泛分布的北美灰树蛙--四倍体(是正常染色体数的2倍)的多倍体物种杂色毛蛙(Hyla Versicolor)和它的二倍体对应种黄蛙(h.chrysoscelis)。主要目的是了解杂色H.chrysoscelis是否不止一次出现，或者作为祖先H.chrysoscelis和另一种二倍体H.avivoca的杂交。多来源假说将通过比较来自广泛地区的所有三种青蛙的线粒体DNA的核苷酸序列来检验它们的分布。如果在基于序列数据的进化树中，不同的杂色夜蛾种群占据不同的分支，则支持多起源的假说。换句话说，在同一区域的两个物种将比来自范围不同部分的相同物种的个体更相似。第二个目标是比较杂色毛虫和金色毛虫交配叫声在它们共同出现的区域(共生)和只出现一个物种的区域之间的差异(异种)的声学特性的差异。因为青蛙只使用交配叫声来识别正确的配偶，而且不匹配会导致不育的三倍体杂交，所以工作假说是，共生群体内部的差异将大于异地种群之间的差异。

Polyploidy in higher animals is generally rare, but more than fifteen species of five different families of frogs and toads have been discovered. The subjects of this research are two widely ranging North American gray treefrogs - the polyploid species Hyla versicolor, a tetraploid (2 times normal chromosome number) and its diploid counterpart, h. chrysoscelis. The main goal is to learn if H. versicolor arose more than once from H. chrysoscelis or as a hybrid between ancestral h. chrysoscelis and another diploid, h. avivoca. The multiple-origin hypotheses will be tested by comparing the nucleotide sequences of mitochondrial DNA from frogs of all three species from widespread areas through their distribution. The hypothesis of multiple- origin will be supported if in an evolutionary tree based on sequence data, different populations of H. versicolor occupy different branches. In other words, the two species in the same area of the range would be more similar to each other than individuals of the same species from different parts of the range. A second goal is to compare differences in the acoustic properties of the mating calls of H. versicolor and H. chrysoscelis in areas where they occur together (sympatry) with differences between areas where only one species occurs (allopatry). Because the frogs use mating calls alone to identify correct mates, and because mismatings lead to sterile, triploid hybrids, the working hypothesis is that differences within sympatry will be greater than differences between allopatric populations.