Dissertation Research: Phylogenetic Systematics, Historical Biogeography, and the Evolution of Vocalizations in Nearctic Toads

对人耳来说，鸟和青蛙的叫声可以区分不同的物种，并可用于物种识别。对鸟或青蛙的耳朵来说，这些叫声是重要的交配信号，对它们的信号和反应具有重要的进化后果。青蛙的叫声，就像我们更熟悉的鸣禽的叫声一样，具有吸引雌性和宣布存在或领土所有权的功能。雌性利用雄性的叫声来选择合适的伴侣。这些信号的变化或雌性对这些信号的反应可能会导致一些雌性更喜欢与某些雄性交配，而不是与其他信号略有不同的雄性交配。这种优先交配是一种生殖隔离，如果维持多代，可能会导致物种形成。因此，交配信号的分化对物种多样性的产生和维持至关重要。在西方蟾蜍（Bufo boreas）中，主要交配信号的产生，称为广告呼叫，只发生在一小部分种群中。一些种群有交配信号而另一些种群没有提供很好的机会来测试潜在的进化模式。雌性偏好和雄性特征的进化将通过DNA测序/分子系统发育、声学和行为分析来研究。这些分析还将允许测试广告呼叫是否丢失然后重新获得，这是以前没有记录的声音交配信号的情况。此外，形态学分析将进行，以评估除了产生叫声的行为决定外，叫声的产生是否需要形态学适应。最后，将对多种蟾蜍物种进行声学分析，以检查广告和第二种呼叫类型（释放呼叫）的变化，以确定释放呼叫是否被某些B. boreas的新型广告功能所采用。更广泛的影响：这项研究涉及与美国和加拿大的教授、研究生和联邦保护生物学家的跨学科培训和合作。所有六种焦点物种都在某种程度上受到保护（州、省和/或联邦），但分类学的不确定性阻碍了保护工作。这项研究将有助于解决进化关系和分类问题。研究结果将发表在科学期刊上，在社会会议上展示，并作为公开讲座和访谈的一部分呈现。DNA序列数据将通过GenBank数据库公开提供。

To the human ear, the calls of birds and frogs distinguish different species and can be used for species identification. To the bird or frog ear, these calls are important mating signals, and the signals and responses to them have major evolutionary ramifications. Frog calls, like the more familiar calls of songbirds, function to attract females and announce presence or territory ownership. Females use the calls of males for selecting suitable mates. Changes in these signals or in how females respond to them may result in some females preferring to mate with certain males over others with a slightly different signal. This preferential mating is one type of reproductive isolation, and if maintained over multiple generations, it may result in speciation. Therefore, divergence in mating signals is critical to the generation and maintenance of species diversity. In western toads, Bufo boreas, production of the major mating signal, termed the advertisement call, only occurs in a small proportion of populations. Species in which some populations have a mating signal and others do not provide excellent opportunities to test for the underlying models of evolution. The evolution of female preferences and male traits will be examined in B. boreas using DNA sequencing/molecular phylogenetic, acoustic, and behavioral analyses. These analyses will also allow testing whether the advertisement call was lost and then re-gained, a scenario not previously documented for an acoustic mating signal. Additionally, morphological analyses will be conducted to assess whether call production requires morphological adaptations in addition to the behavioral decision to produce calls. Finally, acoustic analyses of multiple toad species will be conducted to examine variation in advertisement and a second call type, the release call, to determine if the release call was co-opted for the novel advertisement function in some B. boreas.Broader Impacts: This research involves cross-disciplinary training and collaborations with professors, graduate students, and federal conservation biologists in the United States and Canada. All six of the focal species receive conservation protection at some level (state, provincial, and/or federal), but taxonomic uncertainties have inhibited conservation efforts. This study will help resolve evolutionary relationships and taxonomy. Results will be published in scientific journals, presented at society meetings, and presented as part of public lectures and interviews. DNA sequence data will be made publicly available via the GenBank database.