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Our lab investigates how animals compete and reproduce using a physiological and evolutionary perspective. We are especially interested in how social and reproductive challenges affect physiological function and shape evolutionary outcomes. We address two key questions:
1. How do organisms maintain energy balance and cellular homeostasis during reproduction and territorial defense?
2. How does aggressive competition influence evolutionary diversification?
We focus on the highly social cichlid fish Astatotilapia burtoni, a model in ethology and social neuroscience. Males of this species form lek-like social systems: dominant individuals defend territories and court females, who then mouthbrood the eggs without feeding for over two weeks. Subordinate males lack bright coloration and access to mates. The behavior of these cichlids can be readily tracked and experimentally manipulated in replicated lab communities. In parallel, we also study zebrafish to investigate how alternative stress coping styles relate to brain oxidative stress - complementing our cichlid research on social stress and redox balance in the brain.
To answer our core questions, we combine behavioral experiments with physiological assays, including measurements of oxidative stress, mitochondrial bioenergetics, and gene expression. Because of the tight connection between psychosocial stress, oxidative damage, and disease, our work also has strong relevance to biomedical research. Our research is currently funded by the NIH, NSF and AALAS. Below are some of our current research directions:
Dominant males are territorial, have an upregulated reproductive axis, and are more brightly colored than subordinate males (Images from Maruska and Fernald, 2011; Fernald, 2017).
In many social species, rank within a dominance hierarchy influences access to resources and health. Maintaining high rank can be metabolically taxing while chronic subordination is also stressful. We study how social rank and social stability influence oxidative stress (occurs when reactive oxygen species overwhelm antioxidant system) in A. burtoni cichlids.
We are especially interested in the brain, where oxidative imbalance plays a role in neurodegenerative and psychiatric disorders. As part of this work, I am PI on an NIH-funded project examining how social stress and competition affects patterns of oxidative stress in the brain.
Potential approaches to study the impact of social histories and competition on bioenergetic adaptation in the brain and other tissues.
Animals have different behavioral strategies to cope with stressful situations. Proactive individuals are more risk-seeking, display less behavioral flexibility, and exhibit a lower physiological stress response than reactive individuals. I serve as a collaborator on an INBRE-NE funded project led by Dr. Wong to study how alternative coping styles are linked to oxidative damage and antioxidant capabilities in the zebrafish brain.
Cichlid females invest heavily in reproduction through mouthbrooding, a behavior that prevents feeding for over two weeks. We have previously shown that egg production and mouthbrooding elevate oxidative stress. We are now investigating how females mitigate these costs through antioxidant defenses, mitochondrial adjustments, and behavioral adaptations.
Illustration of reproductive cycle of a cichlid female (left) and the link between reproduction and oxidative status (right).
African cichlids are a textbook example of rapid, 'explosive' speciation resulting in hundreds of endemic cichlid species that vary in behavior, morphology, and reproductive strategies. Competition for mating territories is known to influence speciation and population divergence. Specifically, when similar phenotypes compete intensely, rare phenotypes may gain a fitness advantage, promoting trait divergence (e.g., in color) and reproductive isolation.
I am the lead PI on a collaborative NSF grant (2025-2030) to investigate the cognitive, genetic, and neurogenomic basis of aggression biases. In this multi-institutional project, bringing together evolutionary ecologists and neuroscientists across three continents, we aim to shed light on the behavioral and neural mechanisms driving evolutionary change.
Neural regulation of aggression biases to red and blue Pundamilia (neural activity is labeled with pS6 and TH, image from Calvo et al. 2023)
Environmental enrichment is vital for the welfare of cichlid fish, a key model in behavioral neuroscience. However, structures used for enrichment can promote territorial aggression, posing a risk to the fish that are a target of aggression.
I am the lead PI on a collaborative AALAS grant to study how structural complexity influences aggression, territoriality, and stress, with the goal of developing new recommendations for environmental enrichment.
Visual of the effect of structural complexity on behavior and welfare.
Our cichlid fish facility at CMU.