Research

Why and how do individuals behave the ways that they do?

The Solomon-Lane lab group is interested in understanding individual variation in social behavior. Social behavior is one of the most intensely studied categories of behavior because interactions among members of a social group have important consequences, including for evolutionary fitness and health. There are diverse social species across the animal kingdom, from insects, reptiles, birds, and fish, to mammals, such as humans! To answer behavior questions in the lab, we study Burton’s Mouthbrooder (Astatotilapia burtoni), a highly social species of African cichlid fish. Our research specifically focuses on the development of behavior. Social experiences during early-life have a powerful, long-lasting (and even permanent) effects on future phenotype. We investigate the attributes of those early social experiences – the behavioral mechanisms – that drive developmental plasticity via long-lasting changes in underlying neural and neuroendocrine mechanisms. Working with A. burtoni, we can study social behavior and experience, and its regulatory mechanisms, in all members of a social group.

Burton’s Mouthbrooder (Astatotilapia burtoni)

A. burtoni is a highly social cichlid fish that is native to Lake Tanganyika, the largest of the East African Rift lakes. Cichlid fish are well known for their massive adaptive radiation – there are at least 2,000 different species! Cichlid species differ in their behavior, morphology, and ecological niche. Species also vary in their social and reproductive systems. For example, A. burtoni exhibit maternal care, while other species have paternal care, biparental care, polygamous harems with helpers, or monogamous pairs with helpers.

A. burtoni social communities are made up of adult females and males of two different phenotypes. Dominant males are brightly colored, territorial, aggressive, and reproductively active with females. In contrast, subordinate males are silver (drab) in coloration, non-territorial, and reproductively suppressed. Remarkably, these status phenotypes are plastic! Males regularly transition between dominant and subordinate status over the course of their lives. Females shoal with subordinate males and reproduce with dominant males. A. burtoni gets its common name – Burton’s Mouthbrooder – from female reproductive behavior. Following courtship, a female will lay her eggs in the dominant male’s territory and then immediately collect the eggs in her mouth. The male then fertilizes the eggs in her mouth as she ‘nips’ at the egg spots on his anal fin. The eggs develop into juveniles in the mother’s mouth over the course of ~12 days.

A. burtoni Social Life History

Why study A. burtoni?

A. burtoni is an excellent species for research on social behavior and its underlying regulatory mechanisms. A. burtoni forms naturalistic social communities in the laboratory and expresses a suite of social behaviors common across vertebrates, such as aggression, affiliation, courtship, reproduction, parenting, cooperation, and social learning. The neural mechanisms regulating these behaviors are also highly conserved evolutionarily. Adults regularly reproduce in the lab, making it feasible to study development and maintain a lab population. A substantial amount is already known about the brains and behavior of this species as adults, and our research continues to build on this knowledge by focusing on the development of juveniles!

Background reading

To learn more about A. burtoni as a model system in social neuroscience, check out Maruska & Fernald, 2018.
To learn more about behavioral development – and how much we don’t yet understand – check out Taborsky, 2016.
To learn about behavioral development in A. burtoni, check out the latest from the lab: Harmon et al., 2024.