Mark C Belk, Professor of Biology
How well were academic objectives of the proposal met?
The proposal was to compare life history characteristics and the cost of reproduction tradeoff among populations of a burying beetle (Nicrophorus orbicollis). We conducted two major experiments with the MEG funding directed toward this goal. Both experiments required that we collect beetles from the wild and then raise their offspring in the lab to document responses. First, we compared lifetime reproductive output among two populations at two distinct temperatures. Second, we evaluated parentage of offspring (using newly developed molecular techniques) after manipulation of parental care.
The first experiment required collection of beetles from Wisconsin and Oklahoma. We then allowed the beetles to breed to produce the laboratory population for the experiment. Beetles from both locations were randomly assigned and raised at two different temperatures and on two carcass sizes. Females were allowed to breed throughout their life and we compared lifetime fitness measures and within lifetime patterns of reproduction among treatment combinations. We evaluated two hypotheses about geographic patterns of reproduction. The first, local adaptation, suggests that beetles from each location should do best at the temperature typical of their native location. The second, countergradient variation, suggests that beetles from a more northern location should perform best at all temperatures.
The results suggest support for local adaptation in some reproductive traits and that high temperatures are limiting to burying beetle geographic ranges. These results have important implications for the evolution of the cost of reproduction and effects of climate change on species distributions of burying beetles.
The second experiment required assessment of parentage in the natural environment. We traveled to Wisconsin to apply experimental conditions. We are interested in how culling by males and females affect parental representation in offspring. We placed carcasses in natural environments to attract burying beetles. After a pair had colonized the carcass we applied one of four treatments – 1) leave both parents, 2) remove both parents before culling, 3) remove the male before culling, and 4) remove the female before culling. After the offspring arrived on the carcass and culling was completed we removed the remaining parents and all larvae and preserved them for future genetic analysis to determine parentage of offspring. The hypothesis is that males provide parental care and cull offspring as a way of increasing parentage, rather than to increase overall survival.
We have developed SSR’s and SNP’s to use in the analysis of parentage. We have isolated DNA from all of the individuals collected from the experiment. We hope to have the parentage analysis done within the next few weeks.
Both experiments were highly successful. The data we have collected will provide opportunity for presentation at national academic meetings and publication in high quality journals. Our academic objectives for this project were fully satisfied.
Evaluation of the mentoring environment
Both sets of experiments done as part of this MEG funding involved a large number of students. Students were involved in significant ways. As part of the first experiment students were involved in collection of the beetles in the field, in maintenance of the experiments in the lab, and in data collection. Students were exposed to natural history of the collection locations in Oklahoma and Wisconsin. Also, they became proficient at care of beetles in the lab and collection of data. In the second experiment, several students accompanied us to Wisconsin to run the experiment. These students learned about northern hardwood forest ecosystems in detail by direct experience. Also, additional students learned molecular methods for DNA analysis as well. As part of both experiments on burying beetles students learned laboratory techniques and animal husbandry methods needed to complete a complex experiment. They not only learned the methods, but understood the structure and hypotheses tested by the experiment. I and my graduate students met with the students on a regular basis to discuss their experiences and to help them understand the conceptual issues of the research. Students worked directly with two graduate students on a daily basis. They helped in the research and asked questions of the graduate students. Students were required to send me a weekly email that detailed their understanding and experiences. At the end of the semester or term students were required to submit a 2-3 page report of their experience and understanding. I visited with students about their level of involvement and asked them if they would like to continue with the research and to work toward presentation at a scientific meeting and authorship of a paper.
Two graduate students and two undergraduates are currently working toward publication of a paper from their work on burying beetles. Two other undergraduates are working on publishing papers that are not directly linked to this experiment. These students were introduced to research through these projects, but have since moved to other projects. All students involved in research funded by this MEG are listed below.
- Clint Laidlaw/ presentation at meetings and publishable paper
- Liem Nguyen
- Kevin Mitchell/ presentation at meetings and publishable paper
- Joseph Jeffery/ presentation at meetings and publishable paper
- Matthew Rambo
- Terrance Kim
- Jonathon Vance
- Elias Combs
- Andy Thompson
- Ashton Dyck
- Kaitlyn Seeberger
- Jacob Shelley
Description of results
The results of the first experiment suggest support for local adaptation in some reproductive traits and that high temperatures are limiting to burying beetle geographic ranges. These results have important implications for the evolution of the cost of reproduction and effects of climate change on species distributions of burying beetles.
For the second experiment, we have developed SSR’s and SNP’s to use in the analysis of parentage. We have isolated DNA from all of the individuals collected from the experiment. We hope to have the parentage analysis done within the next few weeks.
Both experiments were highly successful. The data we have collected will provide opportunity for presentation at national academic meetings and publication in high quality journals. Our academic objectives for this project were fully satisfied.
Budget
About one third of the budget was spent on costs of travel for students involved in collecting beetles for the first experiment and those involved in the second experiment in Wisconsin. Another third was used for student wages to help with the maintenance of the two experiments. The final third was used for supplies mainly for the molecular analysis to determine parentage (SSRs and SNPs) and also for mouse carcasses and other supplies for the beetle experiments.