Basic Mechanisms and Evolution of Acoustic Communication

声通信的基本机理和发展主要作者（作者姓名：H。（卡尔·格哈特）沟通影响着信号者和接收者的繁殖成功。因此，通信在进化和物种形成中起着至关重要的作用，信号的差异往往是种群状态的可靠指标，这些种群在物理外观上几乎没有差异。发送者和接收者施加的相互选择压力可能会在信号特性和感觉系统的选择性之间产生精确的匹配。原因是，产生非常不同信号的雄性不太可能吸引配偶，而具有非常独特偏好的接收者可能无法找到自己物种的任何雄性。然而，已经发现了一些例外的例子，其中接收器更有效地刺激信号，这些信号不是由它们自己物种的成员（=同种雄性）产生的，而是由那些密切相关的物种（=异种雄性）产生的。这些新的偏好被称为“隐藏的偏好”，系统发育分析有时表明，偏好早于进化时间的信号，因此这些偏好可以被认为是“预先存在的偏见”。“这个项目是一个比较研究的信号特性和接收器的偏好匹配在一个复杂的九个密切相关的北美树蛙。雄性树蛙会发出简单、刻板的声音，而雌性树蛙会对这些声音或电脑合成的声音做出反应，方法是靠近发出声音的扬声器。使用合成叫声的回放实验将识别女性在信号中进行选择时使用的关键物理特性（=偏好标准）。这些实验将确定每个物种的女性是否最好的响应信号的属性典型的同种男性或其他物种的呼叫或呼叫元素是否可能更有吸引力或可能提高同种呼叫的吸引力。可能会发现，匹配同种呼叫属性是好的，在所有九个物种，不匹配是普遍存在于所有物种，或匹配发生在一些物种，但在其他物种。不管这些实验的结果如何，系统发育分析--将依赖于所有九个物种的形态和分子特征--将被用来表明偏好和信号的进化顺序。这种特殊的树蛙群体也有两个特征，可以帮助解释一种模式，即在某些物种中发生匹配，而在其他物种中发生不匹配。第一，在组中的一些物种通常形成混合物种合唱团与近亲有类似的呼吁。在这里，可以预期的是，为了防止物种之间的交配，受体和受体的匹配将是强有力的。该群体中的其他物种已经与任何其他具有类似叫声的物种隔离了很长一段时间，而其他物种则没有。这些是寻找不匹配（“隐藏的偏好”和“预先存在的偏见”）的最佳候选人，因为这些偏见可能是祖先的特征，可以在没有与另一个物种交配的风险的情况下表达。第二，已经发现组中的一些物种具有其他物种的染色体数目的两倍，并且染色体数目的变化影响呼叫特性。这种染色体数目的变化也可能会影响女性的偏好，这种方式既可以跟踪呼叫的变化，也可以导致呼叫者和接收者的不匹配。这一假设将通过研究青蛙的偏好进行测试，实验诱导额外的染色体组。

BASIC MECHANISMS AND EVOLUTION OF ACOUSTIC COMMUNICATION HOWARD CARL GERHARDT, JR., PRINCIPAL INVESTIGATOR(Name used as an author: H. Carl Gerhardt)Communication affects the reproductive success of signalers and receivers. Thus, communication plays a critical role in evolution and speciation, and differences in signals are often reliable indicators of the status of populations that have diverged little, if at all, in their physical appearance. Mutual selective pressures exerted by senders and receivers might be expected to generate precise matching between signal properties and the selectivity of the sensory system. The reason is that senders that produce very different signals are unlikely to attract mates, and receivers that have very unique preferences may not find any male of their own species acceptable. However, some exceptional examples have been found in which receivers are more effectively stimulated by signals that are not produced by members of their own species (=conspecific males), but by those of closely related species (=heterospecific males). These novel preferences have been called "hidden preferences," and a phylogenetic analysis sometimes shows that the preference predates signals in evolutionary time and can hence such preferences can be considered "pre-existing biases." This project is a comparative study of the matching of signal properties and receiver preferences in a complex of nine closely related North American treefrogs. Male treefrogs produce simple, stereotyped sounds, and females respond to these sounds or to synthetic, computer-generated sounds by approaching a speaker that emits them. Playback experiments using synthetic calls will identify the key physical properties (=preference criteria) used by females to select among signals. These experiments will determine for each species whether females respond best to signals with properties typical of conspecific males or whether calls or call-elements of other species might be more attractive or might enhance the attractiveness of conspecific calls. It might be found that matching to conspecific call properties is good in all nine species, that mismatches are prevalent in all species, or that matching occurs in some species but not in others. Regardless of the results of these experiments, a phylogenetic analysis - which will rely on morphological and molecular characters of all nine species - will be used to suggest the order of evolution of preferences and signals. This particular group of treefrogs also has two features that could help to explain a pattern in which matches occur in some species and mismatches in others. First, some species in the group routinely form mixed-species choruses with close relatives having similar calls. Here it might be expected that matching of senders and receivers will be strong in order to prevent mating between species. Other species in the group have been isolated from any other species with similar calls for long periods of time whereas others. These are the best candidates for finding mismatches ("hidden preferences" and "pre-existing biases") because these biases might be ancestral traits that can be expressed without the risk of mating with another species. Second, it has been found that some species in the group have twice the number of chromosomes of the other species and that changes in chromosome number affect call properties. Such a change in chromosome number might also affect female preferences in ways that could either track the changes in the calls or result in mismatches of senders and receivers. This hypothesis will be tested by studying the preferences of frogs with experimentally induced extra sets of chromosomes.