Title

When to Fight? Disentangling Temperature and Circadian Effects on Aggression

Poster Number

11B

Lead Author Major

Biological Sciences

Lead Author Status

Junior

Format

Poster Presentation

Faculty Mentor Name

Zachary Stahlschmidt

Faculty Mentor Email

zstahlschmidt@pacific.edu

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Agonistic behavior (i.e., fighting) is an important component of intraspecific competition for many animals. Often, outcomes of agonistic contests serve as indicators of individual fitness, helping the victors secure resources (e.g., territory, food, and/or mating rights). Though several factors affecting aggression have been well-documented across taxa (e.g., variation in age or body size), less is known about the effects of abiotic (non-biological) factors on aggression and outcomes of agonistic contests. Ambient temperature and circadian rhythms are two widespread factors that affect many common biological processes, suggesting their potential in modifying aggressive contests. However, it is difficult to disentangle the effects of these covarying factors— in nature, it is cooler early in the photophase (morning) and warmer later in the photophase (afternoon). Thus, I examined the effects of these factors on agonistic behavior using male sand field crickets (Gryllus firmus) that experienced a diel temperature cycle mimicking thermal conditions in their native range during the active season (20.5 °C – 32 °C) throughout adulthood. Crickets were randomly assigned to agonistic trials in a 2 x 2 factorial design, competing in either cool (21.7°C) or warm (31.3°C) conditions, and either early or late into the photophase (6% vs. 75% into the photophase, respectively). Given their potential effect on agonistic behavior, age, wing morphology, and reproductive status were controlled—males were short-winged, 7-8 day old virgin adults. Agonistic encounters were video recorded and analyzed to determine level of overall aggression and ultimate outcomes (i.e., who won and lost). Preliminary results indicate that morphological traits (e.g., body size) may influence the outcome and level of aggression of contests, but the strength or presence of some morphological advantages may depend on temperature or time-of-day. Thus, prominent abiotic and biotic factors may interact to alter the dynamics of agonistic contests, which influence intraspecific competition and individual fitness.

Location

DeRosa University Center, Ballroom

Start Date

29-4-2017 10:00 AM

End Date

29-4-2017 12:00 PM

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Apr 29th, 10:00 AM Apr 29th, 12:00 PM

When to Fight? Disentangling Temperature and Circadian Effects on Aggression

DeRosa University Center, Ballroom

Agonistic behavior (i.e., fighting) is an important component of intraspecific competition for many animals. Often, outcomes of agonistic contests serve as indicators of individual fitness, helping the victors secure resources (e.g., territory, food, and/or mating rights). Though several factors affecting aggression have been well-documented across taxa (e.g., variation in age or body size), less is known about the effects of abiotic (non-biological) factors on aggression and outcomes of agonistic contests. Ambient temperature and circadian rhythms are two widespread factors that affect many common biological processes, suggesting their potential in modifying aggressive contests. However, it is difficult to disentangle the effects of these covarying factors— in nature, it is cooler early in the photophase (morning) and warmer later in the photophase (afternoon). Thus, I examined the effects of these factors on agonistic behavior using male sand field crickets (Gryllus firmus) that experienced a diel temperature cycle mimicking thermal conditions in their native range during the active season (20.5 °C – 32 °C) throughout adulthood. Crickets were randomly assigned to agonistic trials in a 2 x 2 factorial design, competing in either cool (21.7°C) or warm (31.3°C) conditions, and either early or late into the photophase (6% vs. 75% into the photophase, respectively). Given their potential effect on agonistic behavior, age, wing morphology, and reproductive status were controlled—males were short-winged, 7-8 day old virgin adults. Agonistic encounters were video recorded and analyzed to determine level of overall aggression and ultimate outcomes (i.e., who won and lost). Preliminary results indicate that morphological traits (e.g., body size) may influence the outcome and level of aggression of contests, but the strength or presence of some morphological advantages may depend on temperature or time-of-day. Thus, prominent abiotic and biotic factors may interact to alter the dynamics of agonistic contests, which influence intraspecific competition and individual fitness.