Oral Presentations - Session 2B: UC 327
Presentation Type
Presentation
Faculty Mentor’s Full Name
Douglas Emlen
Faculty Mentor’s Department
Division of Biological Sciences
Abstract / Artist's Statement
The origin of novel morphological structures has mystified biologists for centuries. These often-impressive structures appear to spring into existence, without passing through any intermediate forms. An exciting recent discovery in evolutionary biology is that some novel morphologies evolve via co-option of existing gene networks. When these ancient networks are deployed in new locations novel structures can result.
Rhinoceros beetle horns are impressive novel morphologies; some horns are longer than their bearer’s body. There is evidence that dung beetles, another group of horn-bearing beetles, have co-opted the insect appendage patterning pathway (APP) for horn development. Dung beetles diverged from rhinoceros beetles roughly 150 MYA, and horns arose independently in these groups. I propose to investigate whether the APP is also responsible for horn development in the rhinoceros beetle Trypoxylus dichotomus.
RNA interference involves injecting RNA into an organism at a precise time in development. The animal’s enzyme Dicer matches this injected RNA with its own messenger RNA strands and destroys them. Destruction turns off the targeted gene during development, allowing insight into the function of that gene. I will use this technique to silence three candidate genes from the APP in larvae of T. dichotomus. The larvae will then be allowed to continue metamorphosis into adults and I will measure differences in horn characteristics.
If these genes are involved in horn development, I expect to see dramatic differences between the horns of treatment and control beetles. This would suggest that rhinoceros beetles have co-opted the insect APP. Finding no difference in horn morphology, however, would implicate a fundamentally different mechanism for horn evolution. Either way, my studies will provide critical first insights to the origins of these novel traits, and will allow a better understanding of the relative ease of co-opting existing gene pathways for various, and often novel, functions.
Category
Life Sciences
The Origin of Novel Morphologies: A Case Study of a Rhinoceros Beetle
The origin of novel morphological structures has mystified biologists for centuries. These often-impressive structures appear to spring into existence, without passing through any intermediate forms. An exciting recent discovery in evolutionary biology is that some novel morphologies evolve via co-option of existing gene networks. When these ancient networks are deployed in new locations novel structures can result.
Rhinoceros beetle horns are impressive novel morphologies; some horns are longer than their bearer’s body. There is evidence that dung beetles, another group of horn-bearing beetles, have co-opted the insect appendage patterning pathway (APP) for horn development. Dung beetles diverged from rhinoceros beetles roughly 150 MYA, and horns arose independently in these groups. I propose to investigate whether the APP is also responsible for horn development in the rhinoceros beetle Trypoxylus dichotomus.
RNA interference involves injecting RNA into an organism at a precise time in development. The animal’s enzyme Dicer matches this injected RNA with its own messenger RNA strands and destroys them. Destruction turns off the targeted gene during development, allowing insight into the function of that gene. I will use this technique to silence three candidate genes from the APP in larvae of T. dichotomus. The larvae will then be allowed to continue metamorphosis into adults and I will measure differences in horn characteristics.
If these genes are involved in horn development, I expect to see dramatic differences between the horns of treatment and control beetles. This would suggest that rhinoceros beetles have co-opted the insect APP. Finding no difference in horn morphology, however, would implicate a fundamentally different mechanism for horn evolution. Either way, my studies will provide critical first insights to the origins of these novel traits, and will allow a better understanding of the relative ease of co-opting existing gene pathways for various, and often novel, functions.