Lawrence S. Blumer

Social interactions tune aggression and stress responsiveness in a territorial cichlid fish (Archocentrus nigrofasciatus)

We examined the relative influences of pre-fight housing condition, contest intensity, and contest outcome in modulating post-fight stress hormone concentrations in territorial male convict cichlids (Archocentrus nigrofasciatus). Individuals were housed either in isolation or in semi-natural communal tanks. Pairs of male cichlids that differed considerably in body mass were selected from the same housing regime. Pre-fight water-borne cortisol levels were obtained before allowing the dyad to interact until contest resolution, after which time post-fight cortisol levels were obtained from the winner and loser. There were no outcome-related differences in post-fight cortisol concentrations following escalated or non-escalated contests, a result that held true for both housing regimes. Pre-fight cortisol levels were significantly higher than post-fight cortisol levels, suggesting that initial confinement in a beaker for the water-borne hormone samples was a stressor, but that the animals acclimated quickly to confinement. Fights involving previously isolated participants were significantly more intense than those involving group-housed animals, which we explain as being a function of established relationships between social isolation, heightened acute cortisol responsiveness, and the expression of excessive aggressive behavior. Only group-housed losers demonstrated the ability to modulate aggression or hypothalamic-pituitary-interrenal (HPI) activity in a graded fashion to acute increases in cortisol or changes in contest intensity, respectively. We discuss a variety of factors that could disrupt the ability of isolates to appropriately modulate interactions between social behavior and the HPI axis, and we examine a number of functional hypotheses underlying the sensitivity of group-housed losers to changes in contest dynamics.

The gall of subordination: changes in gall bladder function associated with social stress

Diverse physiological and behavioural mechanisms allow animals to effectively deal with stressors, but chronic activation of the stress axis can have severe consequences. We explored the effects of chronic social stress on agonistic behaviour and gall bladder function, a critical but widely neglected component of stress‐induced gastrointestinal dysfunction. Prolonged cohabitation with dominant individuals elicited behavioural modifications and dramatically increased bile retention in subordinate convict cichlid fish (Archocentrus nigrofasciatum). The key predictor of gall bladder hypertrophy was social subordination rather than status‐related differences in food intake or body size. Stress‐induced inhibition of gall bladder emptying could affect energy assimilation such that subordinate animals would not be able to effectively convert energy‐rich food into mass gain. These results parallel changes in gall bladder function preceding cholesterol gallstone formation in humans and other mammals. Thus, social stress may be an important diagnostic criterion in understanding pathologies associated with gall bladder dysfunction.

Inquiry‐based ecology laboratory courses improve student confidence and scientific reasoning skills

Recently, the AAAS Vision and Change report renewed the push to incorporate inquiry throughout the biology curriculum. Even prior to the report, many ecology faculty have used inquiry-based approaches in their laboratory and field courses. However, the efficacy of these approaches has been assessed only to a limited degree and often at a single institution. Therefore, whether one may generalize the results of previous studies of inquiry-based teaching in laboratory courses is unclear. We examined the change in student confidence and scientific reasoning skills using published, validated instruments in inquiry-based ecology laboratory courses at two different institutions (a historically black, all-male, liberal arts college and a private research university) across multiple semesters. Students exhibited a significant increase in overall confidence and scientific reasoning skills with students in the lowest quartile at the beginning of the semester for each construct exhibiting a significantly greater gain in comparison to students in the highest quartile for the same construct. Institution had no effect on learning gains, indicating that the positive impact of inquiry-based learning is general, at least for students at our two institutions. Although weaker students exhibited greater learning gains, significant differences in confidence and scientific reasoning skills between the lowest and highest quartile persisted at the end of the semester; thus, a single, inquiry-based laboratory course is not sufficient to overcome initial differences among students. Interestingly, gains in confidence were not significantly correlated with gains in scientific reasoning with some weaker students increasing in confidence while their scientific reasoning skills decreased, which suggests that our inquiry-based laboratories did not help these students develop important metacognitive skills. Overall, our results indicate that inquiry-based laboratory courses in ecology can lead to significant learning gains, but that performance gaps among students might only be bridged by students taking multiple inquiry-based courses.

Alternative Realities: Faculty and Student Perceptions of Instructional Practices in Laboratory Courses

A survey was developed on inquiry-based learning and assessment in undergraduate laboratory courses and defined five constructs: metacognition, feedback and assessment, scientific synthesis, science process skills, and instructor-directed teaching. In general, faculty and student perceptions were not related at the course and instructor levels.

Effects of Evolutionary History on Adaptation in Bean Beetles, a Model System for Inquiry-based Laboratories

BackgroundCurrent reforms in undergraduate biology education are advancing research experiences in laboratory courses. Such experiences in evolutionary biology have largely been limited to microbial systems.MethodsWe designed a guided-inquiry experiment in which students examine the effect of evolutionary history on the potential for adaptation in the bean beetle (Callosobruchus maculatus), an insect model system widely used in evolutionary biology research. Bean beetles lay their eggs on a variety of species of dried beans (seeds of species in the Fabaceae) and the larvae develop within the bean. They are an ideal model system for studies of experimental evolution in teaching laboratories as they are easy to rear, handle and manipulate. In this study, students design an experiment to determine if adaptation to a particular bean host pre-adapts their offspring to be more successful on a new bean host.ResultsPreliminary experiments by our students suggest that beetles adapted to a lower quality host (adzuki beans, Vigna angularis) are more successful on a new higher quality host (black-eyed peas, Vigna unguiculata) than beetles adapted to a higher quality host (mung beans, Vigna radiata). However, beetles adapted to black-eyed peas are more successful on mung beans than adzuki beans.ConclusionsTaken together, their results show that an evolutionary history on a low quality host might allow bean beetles to be more successful at invading new hosts.

Multi-Institutional, Multidisciplinary Study of the Impact of Course-Based Research Experiences

Numerous national reports have called for reforming laboratory courses so that all students experience the research process. In response, many course-based research experiences (CREs) have been developed and implemented. Research on the impact of these CREs suggests that student benefits can be similar to those of traditional apprentice-model research experiences. However, most assessments of CREs have been in individual courses at individual institutions or across institutions using the same CRE model. Furthermore, which structures and components of CREs result in the greatest student gains is unknown. We explored the impact of different CRE models in different contexts on student self-reported gains in understanding, skills, and professional development using the Classroom Undergraduate Research Experience (CURE) survey. Our analysis included 49 courses developed and taught at seven diverse institutions. Overall, students reported greater gains for all benefits when compared with the reported national means for the Survey of Undergraduate Research Experiences (SURE). Two aspects of these CREs were associated with greater student gains: 1) CREs that were the focus of the entire course or that more fully integrated modules within a traditional laboratory and 2) CREs that had a higher degree of student input and results that were unknown to both students and faculty.