How Does Paired Male Aggression Predict Resource Dominance in More Socially Complex Environments?

Sierra Shepherd

Authors:  Sierra Shepherd, Ummat Somjee, Ginny Greenway

Faculty Mentor: Ginny Greenway

College:  College of Agricultural and Life Sciences


In many species, males invest in competitive traits and behaviors to monopolize access to resources and mates. Oftentimes, a social environment exists in which multiple males compete for access to females, and males with the most aggression gain a reproductive advantage. The majority of studies thus far, however, involve dyadic competition trials which remove the social complexity often present in nature. To bridge this gap, we compared the competitive behaviors of the insect Piezogaster odiosus (Hemiptera: Coreidae) under controlled experimental conditions and then in a more complex social environment. We first paired males in observed competition trials and quantified aggressive behaviors on two successive days. Males were then moved to larger semi-natural enclosures with access to food resources and females. Each enclosure contained a total of 4 males and 2 females, and we recorded the time each male spent on the food resource and mating. We found that males with higher aggression levels in the controlled tests typically spent more time on the resource in the social environment. However this increase in resource holding by individual males did not come with a mating advantage. This study highlights the importance of investigating competitive behaviors in both controlled and socially complex environments.

Poster Pitch

Click the video below to view the student's poster pitch.


Click the image to enlarge.
18 Responses
    1. Sierra Shepherd

      Thank you! I have loved working in the lab so far, and I appreciate everything you taught me last semester! Hope you are doing well.

    1. Sierra Shepherd

      Thank you! I found the results interesting as well, considering so many other studies have found a positive correlation between these two variables in other species.

  1. Caroline Miller

    Hi Sierra,

    This is a fantastic poster! I am interested to know what you defined as “aggression?” For instance, was aggression defined as a direct contact behavior for this species, or are there other indirect behavioral displays that counted as aggression? Also, the results of your study are very interesting. It appears that the male-male competition at play here is resource-dominance only; however, I think we would typically expect this to also correlate to securing mates. I wonder if the males are maximally investing in aggressive behaviors to secure food and therefore can not also maximally in securing a mate as well. This also makes me think about “sneaker males” and how the males that are not as aggressive behaviorally for food are able to more successfully invest in securing a mate instead. Overall, I find your research very interesting! Great job!

    1. Sierra Shepherd

      Exactly my thoughts too! ^_^ I like how you brought up the “sneaker males” concept, and while we found a fairly positive correlation between male size and male aggression levels, it would be interesting to take a closer look at the smaller sized males. As for defining aggression, we scored their observed behaviors over a 2-hour time period: any kicks, grapples, genital contact, and mounting were scored as highly intense behaviors, while antennae contact and approaches were scored as slightly intense. We then combined these scores to try and determine which males we deemed as this most active and most aggressive. We also documented the amount of “retreats” that each male underwent, to try and establish dominance between the two paired male insects.
      Thank you for your interest! I hope I was able to answer your questions.

  2. Kathryn

    Your poster looks great! I like the visuals, they are a great addition to the poster and aid in my understanding of your project. Good organization. Simplified explanations, particularly with the conclusion, were wonderfully written. Great job, Sierra!

  3. Sara Zlotnik

    Hi Sierra,

    Thanks for sharing this awesome project with everyone! I’m curious to hear what you think would be valuable follow-up experiments to test the relationships between competitive dominance, resource holding, and mating success in this species?

    Do you think you might find different results with a larger “pod” that has more green beans and bugs in it? Or maybe if the sex ratio of the bugs was varied?

    Great poster and video by the way! I felt like I was looking at a museum exhibit!


    1. Sierra Shepherd

      Hi Sara,

      Thank you for your interest! I think this study would definitely benefit from larger POD sizes and different sex ratios, so that we might be able to identify any polygyny or polyandry in this species. We also received such a low amount of matings overall that were observed in the PODs, so perhaps if we increased the number of insects and beans in these enclosures, we might receive more data. What I also think would be an interesting comparison to make, is finding a way to separate female preference in terms of male genetics and male size to male resource holding potential. That way, we could gain some more insight into what females are truly attracted to: the potential for gaining access to the resource that male dominates, or the supposed “good” genes that that male might contribute to her offspring.

  4. Emily Angelis

    I love your poster it looks great, and it is really easy to follow! I had great time working with you this semester, hope to see you next year!


    1. Sierra Shepherd

      Thank you, I appreciate it! It was great getting to meet you this semester, and I hope we will see each other again!

  5. Gerardo Nunez

    Hi Sierra! Terrific job here. I really enjoyed your presentation (even if I was thinking about insects eating our harvest in the gardening course).

    Dr. Nunez

    1. Sierra Shepherd

      Hi Dr.Nunez,
      Thank you so much for looking into my poster! And that’s true, I suppose insect resource dominance certainly isn’t great for the bean in question, haha, but at least these insects have stuck within their native habitat unlike some agricultural pests in Florida. I hope you are doing well at this time, and I appreciate everything you taught us last semester. Those vegetables were some of the best I have ever had!