DOI: 10.5061/dryad.2z34tmpsk
title: Quantifying visual acuity in Heliconius butterflies

description: Heliconius butterflies are well-known for their colourful wing patterns,
 which advertise distastefulness to potential predators and are used during
 mate choice. However, the relative importance of different aspects of
 these signals will depend on the visual abilities of Heliconius and their
 predators. Previous studies have investigated colour sensitivity and
 neural anatomy, but visual acuity (the ability to perceive detail) has not
 been studied in these butterflies. Here, we provide the first estimate of
 visual acuity in Heliconius: from a behavioural optomotor assay, we found
 that mean visual acuity = 0.49 cycles-per-degree (cpd), with higher acuity
 in males than females. We also examined eye morphology and report more
 ommatidia in male eyes. Finally, we estimated how visual acuity affects
 Heliconius visual perception compared to a potential avian predator.
 Whereas the bird predator maintained high resolving power, Heliconius lost
 the ability to resolve detail at greater distances, though colours may
 remain salient. These results will inform future studies of Heliconius
 wing pattern evolution, as well as other aspects in these highly visual
 butterflies, which have emerged as an important system in studies of
 adaptation and speciation.
description: # Quantifying visual acuity in *Heliconius* butterflies
 [https://doi.org/10.5061/dryad.2z34tmpsk](https://doi.org/10.5061/dryad.2z34tmpsk) **GENERAL INFORMATION** 1\. Title of Dataset: Quantifying visual acuity in *Heliconius* butterflies 2\. Author Information: 1. Daniel Shane Wright (Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany) 2. Anupama Nayak Manel (Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany) 3. Michelle Guachamin-Rosero (Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany; Universidad Regional Amazónica IKIAM, Tena, Ecuador)  4. Pamela Chamba-Vaca (Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany; Universidad Regional Amazónica IKIAM, Tena, Ecuador)  5. Caroline Nicole Bacquet (Universidad Regional Amazónica IKIAM, Tena, Ecuador)  6. Richard M. Merrill (Division of Evolutionary Biology, Faculty of Biology, LMU Munich, Planegg-Martinsried, Germany) 3\. Date of data collection: 2022\-2023 4\. Geographic location of data collection: Tena\, Napo\, Ecuador 5\. Information about funding sources that supported the collection of the data: ERC starting grant \(Grant number: 851040\) *** **SHARING/ACCESS INFORMATION** 1\. Publications that cite or use the data: Wright DS\, Manel AN\, Guachamin\-Rosero M\, Chamba\-Vaca P\, Bacquet CN\, Merrill RM\. \(2023\)\. Quantifying visual acuity in *Heliconius* butterflies. Biology Letters. 2\. Links to other publicly accessible locations of the data: https://github\.com/SpeciationBehaviour/quantifying\_visual\_acuity 3\. Links/relationships to ancillary data sets: None 4\. Was data derived from another source? No *** **DATA & FILE OVERVIEW** 1\. File list: * cyrbia\_visual\_acuity.R * opt\_cyr.csv * eye\_morph\_cyr.csv * male\_tests.csv 2\. Relationship between files\, if important: None 3\. Additional related data collected that was not included in the current data package: None *** **FILE-SPECIFIC INFORMATION FOR**: cyrbia\_visual\_acuity.R Annotated R-scripts for all related analyses and figures *** **DATA-SPECIFIC INFORMATION FOR**: opt\_cyr.csv The dataset for the behavioural optomotor assay 1\. Number of variables: 11 2\. Number of cases/rows: 49 3\. Variable List: * date: date of optomotor assay (dd.mm.yyyy) * time: time of day for the optomtor assay (hhmm) * weather: outside weather conditions at the time of test (sun = sunny with minimal clouds; over50 = more than 50% cloud cover; overcast = complete cloud cover; rain = rain) * id: individual identification of each butterfly * species: species identify of each butterfly (Cyrbia = *Heliconius erato cyrbia*) * sex: F = female; M = male * origin: source of the butterfly (reared = insectary reared) * date\_emerged: date butterfly emerged from pupae (dd.mm.yyyy) * age: age at testing in number of days * threshold: visual acuity threshold (in cycles per degree) from the optomotor assay * observer: researcher conducting the optomotor test 4\. Missing data codes: None 5\. Specialized formats or other abbreviations used: None *** **DATA-SPECIFIC INFORMATION FOR**: eye\_morph\_cyr.csv The dataset of outer eye morphology measurements 1\. Number of variables: 9 2\. Number of cases/rows: 14 3\. Variable List: * id: individual identification of each butterfly * lmu\_no: sample identification for each preserved butterfly * species: species identify of each butterfly (Cyrbia = *Heliconius erato cyrbia*) * sex: F = female; M= male * L\_count: number of ommatidia in the left eye * R\_count: number of ommatidia in the right eye * L\_tibia: length of the left hind tibia (mm) * R\_tibia: length of the right hind tibia (mm) * observer: researcher conducting the optomotor test 4\. Missing data codes: NA \(data not available\) 5\. Specialized formats or other abbreviations used: None *** **DATA-SPECIFIC INFORMATION FOR**: male\_tests.csv The dataset for additional ‘male only’ optomotor tests ( at levels &gt;1.0 cpd) 1\. Number of variables: 7 2\. Number of cases/rows: 20 3\. Variable List: * date: date of optomotor assay (dd.mm.yyyy) * time: time of day for the optomtor assay (hhmm) * weather: outside weather conditions at the time of test (sun = sunny with minimal clouds; over50 = more than 50% cloud cover; overcast = complete cloud cover; rain = rain) * id: individual identification of each butterfly * sex: F = female; M= male * threshold: visual acuity threshold (in cycles per degree) from the optomotor assay * observer: researcher conducting the optomotor test 4\. Missing data codes: None 5\. Specialized formats or other abbreviations used: None