Distance transform: a tool for the study of animal colour patterns

Summary The information in animal colour patterns plays a key role in many ecological interactions; quantification would help us to study them, but this is problematic. Comparing patterns using human judgement is subjective and inconsistent. Traditional shape analysis is unsuitable as patterns do n...

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Main Authors: Taylor, Christopher H., Gilbert, Francis, Reader, Tom
Format: Article
Published: British Ecological Society 2013
Subjects:
Online Access:https://eprints.nottingham.ac.uk/2445/
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author Taylor, Christopher H.
Gilbert, Francis
Reader, Tom
author_facet Taylor, Christopher H.
Gilbert, Francis
Reader, Tom
author_sort Taylor, Christopher H.
building Nottingham Research Data Repository
collection Online Access
description Summary The information in animal colour patterns plays a key role in many ecological interactions; quantification would help us to study them, but this is problematic. Comparing patterns using human judgement is subjective and inconsistent. Traditional shape analysis is unsuitable as patterns do not usually contain conserved landmarks. Alternative statistical approaches also have weaknesses, particularly as they are generally based on summary measures that discard most or all of the spatial information in a pattern. We present a method for quantifying the similarity of a pair of patterns based on the distance transform of a binary image. The method compares the whole pattern, pixel by pixel, while being robust to small spatial variations among images. We demonstrate the utility of the distance transform method using three ecological examples. We generate a measure of mimetic accuracy between hoverflies (Diptera: Syrphidae) and wasps (Hymenoptera) based on abdominal pattern and show that this correlates strongly with the perception of a model predator (humans). We calculate similarity values within a group of mimetic butterflies and compare this with proposed pairings of Müllerian comimics. Finally, we characterise variation in clypeal badges of a paper wasp (Polistes dominula) and compare this with previous measures of variation. While our results generally support the findings of existing studies that have used simpler ad hoc methods for measuring differences between patterns, our method is able to detect more subtle variation and hence reveal previously overlooked trends.
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spelling nottingham-24452020-05-04T20:19:01Z https://eprints.nottingham.ac.uk/2445/ Distance transform: a tool for the study of animal colour patterns Taylor, Christopher H. Gilbert, Francis Reader, Tom Summary The information in animal colour patterns plays a key role in many ecological interactions; quantification would help us to study them, but this is problematic. Comparing patterns using human judgement is subjective and inconsistent. Traditional shape analysis is unsuitable as patterns do not usually contain conserved landmarks. Alternative statistical approaches also have weaknesses, particularly as they are generally based on summary measures that discard most or all of the spatial information in a pattern. We present a method for quantifying the similarity of a pair of patterns based on the distance transform of a binary image. The method compares the whole pattern, pixel by pixel, while being robust to small spatial variations among images. We demonstrate the utility of the distance transform method using three ecological examples. We generate a measure of mimetic accuracy between hoverflies (Diptera: Syrphidae) and wasps (Hymenoptera) based on abdominal pattern and show that this correlates strongly with the perception of a model predator (humans). We calculate similarity values within a group of mimetic butterflies and compare this with proposed pairings of Müllerian comimics. Finally, we characterise variation in clypeal badges of a paper wasp (Polistes dominula) and compare this with previous measures of variation. While our results generally support the findings of existing studies that have used simpler ad hoc methods for measuring differences between patterns, our method is able to detect more subtle variation and hence reveal previously overlooked trends. British Ecological Society 2013-08 Article PeerReviewed Taylor, Christopher H., Gilbert, Francis and Reader, Tom (2013) Distance transform: a tool for the study of animal colour patterns. Methods in Ecology and Evolution, 4 (8). pp. 771-781. ISSN 2041-210X Keywords: image analysis; individual recognition; MATLAB ; mimicry; signalling; similarity http://onlinelibrary.wiley.com/doi/10.1111/2041-210X.12063/abstract doi:10.1111/2041-210X.12063 doi:10.1111/2041-210X.12063
spellingShingle Keywords: image analysis; individual recognition; MATLAB ; mimicry; signalling; similarity
Taylor, Christopher H.
Gilbert, Francis
Reader, Tom
Distance transform: a tool for the study of animal colour patterns
title Distance transform: a tool for the study of animal colour patterns
title_full Distance transform: a tool for the study of animal colour patterns
title_fullStr Distance transform: a tool for the study of animal colour patterns
title_full_unstemmed Distance transform: a tool for the study of animal colour patterns
title_short Distance transform: a tool for the study of animal colour patterns
title_sort distance transform: a tool for the study of animal colour patterns
topic Keywords: image analysis; individual recognition; MATLAB ; mimicry; signalling; similarity
url https://eprints.nottingham.ac.uk/2445/
https://eprints.nottingham.ac.uk/2445/
https://eprints.nottingham.ac.uk/2445/