Using the FishSim Animation Toolchain to Investigate Fish Behavior: A Case Study on Mate-Choice Copying In Sailfin Mollies

Summary

Using the novel FishSim Animation Toolchain, we present a protocol for non-invasive visual manipulation of public information in the context of mate-choice copying in sailfin mollies. FishSim Animation Toolchain provides an easy-to-use framework for the design, animation and presentation of computer-animated fish stimuli for behavioral experiments with live test fish.

Abstract

Over the last decade, employing computer animations for animal behavior research has increased due to its ability to non-invasively manipulate the appearance and behavior of visual stimuli, compared to manipulating live animals. Here, we present the FishSim Animation Toolchain, a software framework developed to provide researchers with an easy-to-use method for implementing 3D computer animations in behavioral experiments with fish. The toolchain offers templates to create virtual 3D stimuli of five different fish species. Stimuli are customizable in both appearance and size, based on photographs taken of live fish. Multiple stimuli can be animated by recording swimming paths in a virtual environment using a video game controller. To increase standardization of the simulated behavior, the prerecorded swimming path may be replayed with different stimuli. Multiple animations can later be organized into playlists and presented on monitors during experiments with live fish.

In a case study with sailfin mollies (Poecilia latipinna), we provide a protocol on how to conduct a mate-choice copying experiment with FishSim. We utilized this method to create and animate virtual males and virtual model females, and then presented these to live focal females in a binary choice experiment. Our results demonstrate that computer animation may be used to simulate virtual fish in a mate-choice copying experiment to investigate the role of female gravid spots as an indication of quality for a model female in mate-choice copying.

Applying this method is not limited to mate-choice copying experiments but can be used in various experimental designs. Still, its usability depends on the visual capabilities of the study species and first needs validation. Overall, computer animations offer a high degree of control and standardization in experiments and bear the potential to 'reduce' and 'replace' live stimulus animals as well as to 'refine' experimental procedures.

Introduction

Recently, utilizing modern techniques for the creation of artificial stimuli, such as computer animations and virtual reality, has garnered popularity in research¹. These methods provide several advantages compared to classic experimental approaches with live stimulus animals^1,2. Computer animation enables non-invasive manipulation of the appearance (size, color) and behavior of virtual stimulus animals used in experiments. For example, the surgical removal of the sword in male green swordtails (Xiphophorus helleri) to test mate preferences in females³ w....

Protocol

The performed experiments and handling of the fish were in line with the German Animal Welfare legislation (Deutsches Tierschutzgesetz), and approved by the internal animal welfare officer Dr. Urs Gießelmann, University of Siegen, and the regional authorities (Kreisveterinäramt Siegen-Wittgenstein; Permit number: 53.6 55-05).

1. Virtual Fish Design

Note: Find a list of the required hardware and software in the supplementary materials list. A.......

Discussion

The gravid spot in sailfin molly females was previously described to serve as a means of fertility advertisement towards conspecific males^59,60. Whether a gravid spot may also provide information to conspecific females in the context of mate choice had not been tested so far. In the present case study, we investigated the potential role of a gravid spot as a source of public information for observing conspecific females in the context of MCC. Our study shows that.......

Materials

Name	Company	Catalog Number	Comments
Hardware
2x 19" Belinea LCD displays	Belinea GmbH, Germany	Model 1970 S1-P	1280 x 1024 pixels resolution
1x 24" Fujitsu LCD display	Fujitsu Technology Solutions GmbH, Germany	Model B24-8 TS Pro	1920 x 1080 pixels resolution
Computer			Intel Core 2 Quad CPU Q9400 @ 2.66GHz x 4, GeForce GTX 750 Ti/PCIe/SSE2, 7.8 GiB memory, 64-bit, 1TB; keyboard and mouse
SONY Playstation 3 Wireless Controller	Sony Computer Entertainment Inc., Japan	Model No. CECHZC2E	USB-cable for connection to computer
Glass aquarium			100 cm x 40 cm x 40 cm (L x H x W)
Plexiglass cylinder	custom-made		49.5 cm height, 0.5 cm thickness, 12 cm diameter; eight small holes (approx. 5 mm diameter) drillt close to the end of the cylinder lower the amount of water disturbance while releasing the fish
Gravel
2x OSRAM L58W/965	OSRAM GmbH, Germany		Illumination of the experimental setup
2x Stopwatches
Name	Company	Catalog Number	Comments
Software
ubuntu 16.04 LTS			Computer operating system; Download from: https://www.ubuntu.com/
FishSim Animation Toolchain v.0.9			Software download and user manual (PDF) from: https://bitbucket.org/EZLS/fish_animation_toolchain
GIMP Gnu Image Manipulation Program (version 2.8.22)			Download from: https://www.gimp.org/