Dissertation Research: Linking Broad-Scale Genetic Variation and Local Selection on Sexual Signals: Loss of Calling in a Parasitized Population of Field Crickets

这项研究将考察用于吸引配偶的信号是如何受到一个物种在新地区定居时逐渐发生的基因变化的影响，以及在新环境中由于选择而发生的更剧烈的变化，以一只蟋蟀为模型生物。这种蟋蟀名叫Teleogryllus oceanicus，在澳大利亚和许多太平洋岛屿上都有发现，后来被引入夏威夷，在那里它遇到了一个致命的敌人——寄生蝇。这种苍蝇被雄性蟋蟀摩擦翅膀发出的求偶信号（歌声）所吸引。最近，夏威夷发生了一个惊人的变化。在夏威夷的一个种群中，90%的雄性在短短几十代内就从正常的翅膀形态转变为无功能的突变翅膀。这些雄性被苍蝇保护起来，因为它们不能唱歌。这项研究将确定与范围扩大、岛屿殖民化和岛屿间移动有关的逐渐遗传分化对种群间遗传变异分布的重要性。在12个已知的蟋蟀种群的鸣叫和信号行为变异中，关键基因序列的变异将被研究对长期遗传变化的影响。通常一次只有几只动物在岛上定居，这被认为有利于那些在择偶时不那么挑剔的雌性，所以这些历史事件也可能影响交配偏好。其次，这项研究将确定，随着蟋蟀性信号——鸣叫——的迅速消失，它们的行为会发生什么变化。这将通过在澳大利亚大陆和岛屿上的蟋蟀种群之间进行交配来完成，包括那些失去了呼叫能力的蟋蟀种群。智力优势：这项研究将长期的历史过程与短期的局部选择对性信号的影响联系起来。这将有助于我们理解寄生虫影响交配系统的方式，并将增加我们对信号进化模式和速度的理解。更广泛的影响：蟋蟀鸣声的消失是一个引人注目的、容易理解的日常进化的例子，所有层次的学生（从小学到本科）和非科学家都能理解。这个例子，由于其相对简单和最近的时间框架，将促进公众对进化过程的理解，并被用作一种教育工具。此外，该项目将增加UCR的本科生奖学金。pi指导本科生，并将继续将他们纳入本项目的行为方面。

This research will examine how signals used to attract mates are affected by, gradual genetic changes as a species colonizes new areas, and are punctuated by more drastic changes due to selection in new environments, using a field cricket as a model organism. The cricket, Teleogryllus oceanicus, is found in Australia and on many Pacific islands and was introduced to Hawaii where it encounters a deadly enemy, a parasitic fly. The fly is attracted to the mating signal (song) male crickets produce by rubbing their wings together. Recently, a striking change was noted in Hawaii. In one Hawaiian population, but not others, 90% of males shifted from normal wing morphology to a non-functional, mutated wing in just tens of generations. These males are protected from the fly because they cannot produce song. This research will identify the importance of gradual genetic divergence associated with range expansion, island colonization and movement between islands for the distribution of genetic variation among populations. Variation in the key genetic sequences among 12 cricket populations with known variation in song and signaling behavior among the same populations will be examined with respect to implications for long-term genetic change. Islands are usually only colonized by a few animals at a time and this is thought to favor females that are less picky in mate choice, so these historical events are likely to affect mating preferences as well. Second, this research will determine what behavioral changes accompany the recent and rapid loss of the crickets sexual signal, song. This will be accomplished by staging mating encounters between mainland Australian and island populations of the cricket, including those in which the ability to call has been lost. Intellectual merit: This research links the influences of long-term, historical processes with short-term local selection on sexual signals. It will contribute to our understanding of the way parasites influence mating systems and will add to our understanding of the mode and tempo of signal evolution. Broader impacts: The loss of cricket song is a striking and easily understood example of everyday evolution that can be comprehended by students of all levels (grade school to undergraduate) and non-scientists as well. This example, because of its relative simplicity and recent time frame, will advance the publics understanding of evolutionary processes and be used as an educational tool. Additionally, this project will add to undergraduate scholarship at UCR. The PIs mentor undergraduate students and will continue to include them in the behavioral aspects of this project.