Dissecting the variation of a visual trait: The proximate basis of UV-Visible reflectance in crab spiders (Thomisidae)

Felipe M. Gawryszewski, Debra Birch, Darrell J. Kemp, Marie E. Herberstein

Research output: Contribution to journalArticleResearchpeer-review

Abstract

The astounding diversity of animal coloration is indicative of a wide variety of selection pressures. Despite great interest in adaptive function, detailed understanding of the constituent elements of colour traits is lacking for many systems. Such information is important in allowing more accurate appraisals of colour variation and its potential production costs. In this study, we 'dissect' the dorsal colour of crab spiders (Thomisidae) to examine the mechanistic basis of a polyphenic colour trait. These spiders possess the ability to alter reflectance in the ultraviolet (UV), violet and blue wavelengths, changing their colour within days. We investigate and compare the proximate mechanistic basis of colour production in multiple phenotypes of three species using histology and spectrophotometry. Our analyses indicate that the spider cuticle is not equivalently transparent to light across the spectrum (300-700 nm) - as previously argued - and contributes to colour variation. UV light is reflected from guanine crystals, present in storage cells ventral to the hypodermis. The crystals are exposed through a partially UV-transmitting hypodermis and cuticle. Variation from white to yellow is likely mediated through pigments/crystals present in different oxidative stages in the hypodermal cells. Simple mechanistic changes are therefore necessary to produce the observed variation, and likely underlie the evolutionary and ontogenetic lability of this trait. Our findings imply that either a UV-reflective abdomen was the ancestral state for crab spiders, or, if pre-dated by UV-absorbent hypodermal pigments, the evolution of UV reflection has only involved the exposure of underlying guanine crystals through an otherwise clear hypodermis.

LanguageEnglish
Pages44-54
Number of pages11
JournalFunctional Ecology
Volume29
Issue number1
DOIs
Publication statusPublished - 1 Jan 2015

Fingerprint

Thomisidae
spider
reflectance
crab
color
crystals
crystal
cuticle
guanine
pigment
Araneae
pigments
histology
absorbents
production cost
spectrophotometry
phenotype
economic valuation
production costs
abdomen

Cite this

@article{b82551c0dec541118209b1dcdeebff3e,
title = "Dissecting the variation of a visual trait: The proximate basis of UV-Visible reflectance in crab spiders (Thomisidae)",
abstract = "The astounding diversity of animal coloration is indicative of a wide variety of selection pressures. Despite great interest in adaptive function, detailed understanding of the constituent elements of colour traits is lacking for many systems. Such information is important in allowing more accurate appraisals of colour variation and its potential production costs. In this study, we 'dissect' the dorsal colour of crab spiders (Thomisidae) to examine the mechanistic basis of a polyphenic colour trait. These spiders possess the ability to alter reflectance in the ultraviolet (UV), violet and blue wavelengths, changing their colour within days. We investigate and compare the proximate mechanistic basis of colour production in multiple phenotypes of three species using histology and spectrophotometry. Our analyses indicate that the spider cuticle is not equivalently transparent to light across the spectrum (300-700 nm) - as previously argued - and contributes to colour variation. UV light is reflected from guanine crystals, present in storage cells ventral to the hypodermis. The crystals are exposed through a partially UV-transmitting hypodermis and cuticle. Variation from white to yellow is likely mediated through pigments/crystals present in different oxidative stages in the hypodermal cells. Simple mechanistic changes are therefore necessary to produce the observed variation, and likely underlie the evolutionary and ontogenetic lability of this trait. Our findings imply that either a UV-reflective abdomen was the ancestral state for crab spiders, or, if pre-dated by UV-absorbent hypodermal pigments, the evolution of UV reflection has only involved the exposure of underlying guanine crystals through an otherwise clear hypodermis.",
author = "Gawryszewski, {Felipe M.} and Debra Birch and Kemp, {Darrell J.} and Herberstein, {Marie E.}",
year = "2015",
month = "1",
day = "1",
doi = "10.1111/1365-2435.12300",
language = "English",
volume = "29",
pages = "44--54",
journal = "Functional Ecology",
issn = "0269-8463",
publisher = "Wiley-Blackwell, Wiley",
number = "1",

}

Dissecting the variation of a visual trait : The proximate basis of UV-Visible reflectance in crab spiders (Thomisidae). / Gawryszewski, Felipe M.; Birch, Debra; Kemp, Darrell J.; Herberstein, Marie E.

In: Functional Ecology, Vol. 29, No. 1, 01.01.2015, p. 44-54.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Dissecting the variation of a visual trait

T2 - Functional Ecology

AU - Gawryszewski, Felipe M.

AU - Birch, Debra

AU - Kemp, Darrell J.

AU - Herberstein, Marie E.

PY - 2015/1/1

Y1 - 2015/1/1

N2 - The astounding diversity of animal coloration is indicative of a wide variety of selection pressures. Despite great interest in adaptive function, detailed understanding of the constituent elements of colour traits is lacking for many systems. Such information is important in allowing more accurate appraisals of colour variation and its potential production costs. In this study, we 'dissect' the dorsal colour of crab spiders (Thomisidae) to examine the mechanistic basis of a polyphenic colour trait. These spiders possess the ability to alter reflectance in the ultraviolet (UV), violet and blue wavelengths, changing their colour within days. We investigate and compare the proximate mechanistic basis of colour production in multiple phenotypes of three species using histology and spectrophotometry. Our analyses indicate that the spider cuticle is not equivalently transparent to light across the spectrum (300-700 nm) - as previously argued - and contributes to colour variation. UV light is reflected from guanine crystals, present in storage cells ventral to the hypodermis. The crystals are exposed through a partially UV-transmitting hypodermis and cuticle. Variation from white to yellow is likely mediated through pigments/crystals present in different oxidative stages in the hypodermal cells. Simple mechanistic changes are therefore necessary to produce the observed variation, and likely underlie the evolutionary and ontogenetic lability of this trait. Our findings imply that either a UV-reflective abdomen was the ancestral state for crab spiders, or, if pre-dated by UV-absorbent hypodermal pigments, the evolution of UV reflection has only involved the exposure of underlying guanine crystals through an otherwise clear hypodermis.

AB - The astounding diversity of animal coloration is indicative of a wide variety of selection pressures. Despite great interest in adaptive function, detailed understanding of the constituent elements of colour traits is lacking for many systems. Such information is important in allowing more accurate appraisals of colour variation and its potential production costs. In this study, we 'dissect' the dorsal colour of crab spiders (Thomisidae) to examine the mechanistic basis of a polyphenic colour trait. These spiders possess the ability to alter reflectance in the ultraviolet (UV), violet and blue wavelengths, changing their colour within days. We investigate and compare the proximate mechanistic basis of colour production in multiple phenotypes of three species using histology and spectrophotometry. Our analyses indicate that the spider cuticle is not equivalently transparent to light across the spectrum (300-700 nm) - as previously argued - and contributes to colour variation. UV light is reflected from guanine crystals, present in storage cells ventral to the hypodermis. The crystals are exposed through a partially UV-transmitting hypodermis and cuticle. Variation from white to yellow is likely mediated through pigments/crystals present in different oxidative stages in the hypodermal cells. Simple mechanistic changes are therefore necessary to produce the observed variation, and likely underlie the evolutionary and ontogenetic lability of this trait. Our findings imply that either a UV-reflective abdomen was the ancestral state for crab spiders, or, if pre-dated by UV-absorbent hypodermal pigments, the evolution of UV reflection has only involved the exposure of underlying guanine crystals through an otherwise clear hypodermis.

UR - http://www.scopus.com/inward/record.url?scp=84940242817&partnerID=8YFLogxK

U2 - 10.1111/1365-2435.12300

DO - 10.1111/1365-2435.12300

M3 - Article

VL - 29

SP - 44

EP - 54

JO - Functional Ecology

JF - Functional Ecology

SN - 0269-8463

IS - 1

ER -