boldness-aggression-shoaling-assays-for-zebrafish-behavioral

Boldness, Aggression, and Shoaling Assays for Zebrafish Behavioral Syndromes

A behavioral syndrome exists when specific behaviors interact under different contexts. Zebrafish have been test subjects in recent studies and it is ...

Saint Joseph’s University

Many aspects of the reproductive behavior of Drosophila melanogaster are modified dramatically by experience and age. Males' courtship of immature males and fertilized females decreases over time. Females' receptivity to copulation, and the behaviors that females perform and elicit, are affected by their age and sexual experience. We show that mutations in a raised stock affect all of these age- and experience-dependent aspects of male and female sexual behavior. Experience has no effect on raised males' courtship of immature males and has opposite effects on raised and wild-type males' courtship of fertilized females. In comparison to controls, raised females become sexually mature at an earlier age, and sexually mature raised virgin females copulate more quickly. Following mating, raised females elicit more courtship and remate faster and more frequently than control females.

Mutations in raised Drosophila melanogaster affect experience-dependent aspects of sexual behavior in both sexes.

The Biodiversity Laboratories at Saint Joseph's University house more than 100 exotic and endangered animal species-including insects, fish, amphibians, and reptiles. Research in the laboratories is devoted, primarily, to understanding the genetic and ecological bases of animal behavior. In addition, a common theme of the work is the development of techniques for the successful care of exotic animals within a laboratory setting. Such techniques may be critical to studies aimed at understanding the life histories of endangered species and saving them from extinction. Current projects to study the biology of tropical poison frogs have methodologies to improve captive care, maintenance, and breeding. In this article, I present these methodologies and their impact on the welfare of captive poison frogs.

Methodologies for the care, maintenance, and breeding of tropical poison frogs.

Owing to a lack of basic information on the biology of zebrafish (Danio rerio), lab managers must often base decisions regarding the care and use of this species on anecdotal information. In an effort to provide researchers with context-specific behavioral information, the authors evaluated shoaling and spawning behaviors in small groups of zebrafish. In each shoaling assay, a fish was given a choice to shoal with either a single fish or a group of three fish. Females preferred to shoal with a group of three individuals rather than with a single individual, regardless of the sex of the other fish. Males preferred groups of three males over single males but preferred single females to groups of three females. In spawning assays, zebrafish were placed in breeding tanks in one of three sex ratios (1 male:1 female; 3 males:1 female; 1 male:3 females). Reproductive efficiency did not differ among groups, but aggression (evaluated according to presence of shed scales) was more frequently observed in the male-dominated treatment group.

Shoaling preferences and the effects of sex ratio on spawning and aggression in small laboratory populations of zebrafish (Danio rerio).

A behavioral syndrome is observed in a population when specific behaviors overlap at the individual level in different contexts. Here, we explore boldness and aggression personality spectra, the repeatability of shoaling, and possible associated correlations between the behaviors in a population of lab-reared zebrafish (Danio rerio). Our findings describe a sex-specific boldness-shoaling behavioral syndrome, as a link between boldness and shoaling behaviors is detected. The results indicate that bold males are likely to have a stronger shoaling propensity than shy males for unfamiliar conspecifics. Conversely, bold females are more likely to shoal than shy females, but only when presented with heterospecific individuals. Additionally, aggression does not correlate with boldness or shoaling propensity for either sex. A positive relationship between boldness and shoaling that differs by sex is contrary to most of the present literature, but could help to explain population dynamics and may also have evolutionary implications.

Sex differences in a shoaling-boldness behavioral syndrome, but no link with aggression.

Aggression is a psychological construct that is commonly used to classify zebrafish behavior. Aggression is a complex trait that can be difficult to accurately measure. The literature on fish behavior describes many different methodologies to examine aggression, which, we believe, have not been compared in a formal manner. In this study we observed 19 individual zebrafish (Danio rerio) and quantified bites, lateral displays, charges, darts, and time near the stimulus in six common assays used to measure aggression. The methodologies included an inclined mirror assay, two flat mirror assays with different acclimation periods, a live conspecific assay, a clay model stimulus assay, and a video recording assay. Our results indicate high repeatability in most aggressive behaviors over time, which confirms the value of each assay to measure personality. However, our results also indicate significant differences between the assays. Specifically, assays using a flat mirror or live conspecific as a stimulus for aggression elicited more attempted bites than an inclined mirror, a clay model stimulus, or a video recording stimulus. Furthermore, the inclined mirror stimulus provoked more darts than any other assay. The results suggest the need for researchers to consider specific research goals when selecting the appropriate stimulus to provoke aggression in zebrafish.

A comparison of methodologies to test aggression in zebrafish.

A behavioral syndrome is considered present when individuals consistently express correlated behaviors across two or more axes of behavior. These axes of behavior are shy-bold, exploration-avoidance, activity, aggression, and sociability. In this study we examined aggression, boldness and sociability (shoaling) within a juvenile convict cichlid brood (Amatitlania nigrofasciatus). Because young convict cichlids are social, we used methodologies commonly used by ethologists studying social fishes. We did not detect an aggression-boldness behavioral syndrome, but we did find that the aggression, boldness, and possibly the exploration behavioral axes play significant roles in shaping the observed variation in individual convict cichlid behavior. While juvenile convict cichlids did express a shoaling preference, this social preference was likely convoluted by aggressive interactions, despite the small size and young age of the fish. There is a need for the development of behavioral assays that allow for more reliable measurement of behavioral axes in juvenile neo-tropical cichlids.

Scott P. McRobert

Department of Biology

Saint Joseph’s University

Boldness, Aggression, and Shoaling Assays for Zebrafish Behavioral Syndromes

Scott P. McRobert

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Biology

Saint Joseph’s University

Boldness, Aggression, and Shoaling Assays for Zebrafish Behavioral Syndromes

Department of Biology