Document Type

Thesis

Date of Degree Completion

Spring 2023

Degree Name

Master of Science (MS)

Department

Biology

Committee Chair

Lixing Sun

Second Committee Member

Alison Scoville

Third Committee Member

Jason Irwin

Abstract

Dominance hierarchies are typically formed so that members of the hierarchy can benefit from residing in a social structure where conflict is decreased, and each individual obtains a rank within the group. Members can either actively seek out a higher social rank to maximize fitness or remain in a lower position to benefit from the protection of living in a group. This study was designed to manipulate the social stability typically exhibited within hierarchies by experimentally increasing social perturbance in groups of tropical house crickets, Gryllodes sigillatus. Rank changes per unit time were used as a measure to understand how the stability within the hierarchies was impacted. Physical attributes that contribute to rank position in the hierarchy was also examined in this study to aid in our understanding of how crickets establish dominance.

Crickets were ranked on dominance displays and aggressive behaviors including chirping, grappling, kicking and antennal fencing. Varying degrees of perturbation were applied to the cricket hierarchies to measure stability. Perturbation involved removing individuals in the group and replacing them with new crickets. As more individuals were swapped out, rank advancements increased for the remaining individuals. This provided an indication that stability in the hierarchy had been compromised. Lower ranked individuals in groups where high perturbation was applied were more likely to advance their rank compared to the most dominant individuals in those same groups. Understanding the causes and consequences of social mobility and rank stability are important regardless of the study organism. Contributing more insight on the connection between social dynamics and stability can help us understand what drives the persistence of dominance hierarchies over time.

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