Despite a century of intensive research, fertilization is one of the least understood fundamental biological processes. Current theory predicts that membrane-bound proteins promote gamete recognition, but soluble-egg compounds attracting conspecific sperm could also act as pre-zygotic factors maintaining species integrity while increasing fertilization rates. Whereas cell contact recognition between male and female gametes is critical for sexual reproduction, the role of soluble egg factors remains undetermined. Using abalone (genus Haliotis), this project combines a formative conceptual framework with unprecedented techniques and infrastructure to establish the chemical 'language' of sperm and egg. It is expected to provide the first concrete evidence that barriers to hybridization can function prior to gamete contact, and that remote chemical signals can promote speciation. This study has implications for reproductive biology in humans as well as wildlife conservation. Future research could advance innovative approaches for solving problems in human contraception and infertility, using abalone as a valuable animal model: working with German colleagues, the investigators have identified and cloned genes coding for chemoreceptors on human sperm membranes. Recent discoveries link receptor function with sperm attraction to egg. Compelling challenges in conservation biology also will benefit from new knowledge of sensory stimuli controlling fertilization. For many threatened or endangered species, from abalone and corals to apes and elephants, fertilization is the bottleneck to species proliferation. Basic research on sperm chemoattraction is likely to yield original solutions to age old problems in reproductive biology. In captive breeding programs, for example, soluble sperm attractants could be used to identify the most promising sperm donors. Assuming gamete compatibility between mates, a donor with fast and chemo-responsive sperm may enhance the probability of fertilization while potentially improving offspring quality. The investigators have a strong tradition of active community outreach and undergraduate and graduate education. In particular, this project will invigorate training of women and underrepresented students in interdisciplinary research, towards careers in physiology, genetics, and environmental sciences.
Social behaviors are among the most extraordinary actions displayed by living entities. For example, social interactions between gametes are fundamentally important to the survival of species. The goal of this research project was originally focused on studying social interactions between gametes, but changed from understanding gamete interactions to understanding social animal interactions. Thus this research project advanced our understanding of social behavior in animals by studying the molecular basis underlying sociality in advanced social species. The development of sociality represents an extremely important innovation in biological history. Social insects, which include ants, termites, some bees, and some wasps, represent critical models for understanding social behavior. In addition, social insects, such as bees, are key pollinators of crops. Moreover, other social insects, such as some termites, ants, and wasps, are serious invasive pests. Thus understanding social interactions in insects has important economic and scientific consequences. This research focused on investigating the genetic basis underlying social behavior. The research team determined how genes for social behavior change and become prevalent within populations. This theoretical work discovered that the relationships of individuals can have important consequences for the development of advanced social behavior and group success. The completed research also studied how heritable factors interact to affect gene function in social insects. These studies found strong associations between important, heritable molecular mechanisms and how specific sets of genes operate in social species. Finally, this program studied how pest social insects survive winter conditions. This investigation found that social insects show important morphological characteristics that help them survive harsh conditions. In addition to completing several research objectives related to understanding sociality, this program also led to the training of several scientists. Undergraduate and graduate students worked together to complete research goals and learn about the scientific process. This program also brought together scientists from different academic institutions to help promote biology to groups typically underrepresented in the sciences. In addition, information related to this project was disseminated broadly through publication of results and through scientific talks given to both professional societies and general audiences. In conclusion, this research program diverged from early objectives in order to study social behavior. The work ultimately yielded important insights into the molecular mechanisms governing sociality and the genetic basis of development. The research also provided information on insects that have important economic and ecological impact. Finally, this program helped train a generation of new scientists.
