Origin and diversification of evolutionary novelties: insights through the study of beetle horns, insect wings, and bilaterian heads

点击翻译按钮获取中文摘要

Understanding how novel complex traits such as eyes, feathers, or light-producing organs originate is a fundamental goal of the biological sciences. This work will investigate how nature innovates, by using insects as model organisms, and by assessing the significance of two proposed, alternative routes to novelty. The first route posits that much innovation is made possible through the re-use- and re-combination of already existing biological features, from genes to tissue types to organs, not unlike how the pre-existing building blocks of Lego creations can be reassembled and recombined to generate novel structures. The second route in turn emphasizes how novel traits may originate from scratch, piece by piece over time. Ultimately, the work will contrast the mechanisms, efficiency, and consequences of innovation via these two routes, and how they may help us understand why and how life on earth has innovated and diversified the way it has. This work will also be leveraged to further expand an existing, highly successful collaboration with a children's museum to train science teachers in support of Indiana Science Teaching Standards, and to develop teaching resources for special education and ESL students. Similarly, this work will be used to enhance the participation of underrepresented minorities in science through the research team's participation in three award winning summer programs and the recruitment of minority High School students into the group for individualized summer research immersion. Lastly, this work will train at least six scientists in interdisciplinary research.How novel, complex traits originate, how they integrate into preexisting contexts without disruption, and the developmental properties that facilitate their subsequent diversification, all remain overall poorly understood. This work utilizes horned beetles, and the disparate routes of innovation exemplified by different types of horns, to address these challenges. The first major objective focuses on prothoracic horns, which preliminary evidence strongly suggests have evolved through the repurposing of wing serial homologs, and explores how innovation may be facilitated and biased if it relies on the re-use of preassembled morphological structures, their developmental underpinnings and gene networks. The outcomes of this effort will be contrasted to those of the second major objective, which explores how innovation is enabled and directed in circumstances when large scale exaptation of pre-existing modules is not an option. This second objective will utilize the head horns of horned beetles as a focal trait, which lack even remote homology to other insect structures, and which preliminary data show evolved in the absence of large scale repurposing. Contrasting the outcomes of both objectives will afford assessment of the distinctness and commonalities of both routes of innovation with respect to biases, constraints, and resulting developmental architectures. This work will be executed using comparative RNAsequencing and surveys of gene function across multiple species selected based on their phylogenetic positions and the degree of innovation embodied by their focal traits.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.