Collaborative Research: The Chemical Basis of Ethological Isolation

了解物种形成过程背后的遗传机制是进化生物学长期追求的目标。例如，长期以来人们一直认为，基因突变导致生殖过程中用于交流的化学物质（信息素）略有不同，这可能会促进种群的隔离，并最终导致新物种的出现。这个研究项目利用一组经过充分研究的两栖动物来解决这个问题。陆生“无肺”蝾螈进化出了一种生物化学通讯系统，求偶的雄性在求偶期间向雌性发送信息素，以增加雌性的接受能力。信息素是由雄性下巴上的一个腺体产生的，从这个腺体中提取的物质含有蛋白质，这些蛋白质已经被部分纯化和鉴定，并用于行为实验。这些蛋白质含有多种同种异构体，其数量和类型在不同物种之间和同一物种内的不同种群之间有所不同。任何单一同种异构体的流行是否提供生殖优势或促进进化种群之间的隔离是未知的。在本研究中，我们将研究这些蛋白的生化特性及其在促进蝾螈群体行为隔离中的作用。该研究由两个机构的科学家合作进行，研究方向有两个：1)对腺体提取物的主要蛋白质成分进行生化表征（相对浓度、分子质量、氨基酸组成和n端序列）；2)行为生物测定，以确定各种同种异构体在诱导不同种群的雌性蝾螈接受性和/或促进隔离方面的生物活性。综上所述，这些研究将有助于深入了解物种形成过程的生化基础。

9709355 Feldhoff Understanding the genetic mechanisms underlying the process of speciation is a long-sought goal in evolutionary biology. For example, it has long been thought that genetic mutations resulting in slight differences in chemicals used in communication during the reproductive process (pheromones) might promote isolation of populations, and ultimately the emergence of new species. This research project addresses this question using a well-studied group of amphibians. Terrestrial "lungless" salamanders have evolved a biochemical communication system in which courting males administer a pheromone to females during courtship which increases female receptivity. The pheromone is produced by a gland on the male's chin, and extracts from this gland contain proteins, which have been partially purified and characterized, and used in behavioral experiments. These proteins contain multiple isoforms, the amounts and types of which vary between species and among populations within a single species. Whether the prevalence of any single isoform offers reproductive advantages or promotes isolation between evolving populations is unknown. In the present study, the biochemical characteristics of these proteins and their role in promoting behavioral isolation among salamander populations will be investigated. The research is a collaboration between scientists at two institutions and has two directions: 1) biochemical characterization of the major protein components of gland extracts (relative concentrations, molecular mass, amino acid composition, and N-terminal sequence); and 2) behavioral bioassays to determine the biological activity of the various isoforms in eliciting receptivity in female salamanders from different populations, and/or fostering isolation. Taken together, these studies will allow insights into the biochemical basis of the process of speciation.