Colour pattern variation forms local background matching camouflage in a leaf‐mimicking toad

2021 ◽  
Vol 34 (10) ◽  
pp. 1531-1540
Author(s):  
James B. Barnett ◽  
Constantine Michalis ◽  
Nicholas E. Scott‐Samuel ◽  
Innes C. Cuthill
Keyword(s):  
Colour Pattern ◽  
Background Matching ◽  
Local Background

scholarly journals From Abbott Thayer to the present day: what have we learned about the function of countershading?

2008 ◽  
Vol 364 (1516) ◽  
pp. 519-527 ◽  
Author(s):  
Hannah M Rowland
Keyword(s):  
Empirical Work ◽  
Quantitative Measure ◽  
Convincing Evidence ◽  
Colour Pattern ◽  
Protective Effects ◽  
Empirical Testing ◽  
Background Matching ◽  
Visual Characteristics ◽  
Subjective Evidence ◽  
The Many

Of the many visual characteristics of animals, countershading (darker pigmentation on those surfaces exposed to the most lighting) is one of the most common, and paradoxically one of the least well understood. Countershading has been hypothesized to reduce the detectability of prey to visually hunting predators, and while the function of a countershaded colour pattern was proposed over 100 years ago, the field has progressed slowly; convincing evidence for the protective effects of countershading has only recently emerged. Several mechanisms have been invoked for the concealing function of countershading and are discussed in this review, but the actual mechanisms by which countershading functions to reduce attacks by predators lack firm empirical testing. While there is some subjective evidence that countershaded animals match the background on which they rest, no quantitative measure of background matching has been published for countershaded animals; I now present the first such results. Most studies also fail to consider plausible alternative explanations for the colour pattern, such as protection from UV or abrasion, and thermoregulation. This paper examines the evidence to support each of these possible explanations for countershading and discusses the need for future empirical work.

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

scholarly journals Evolutionary fine-tuning of background-matching camouflage among geographical populations in the sandy beach tiger beetle

2020 ◽  
Vol 287 (1941) ◽  
pp. 20202315
Author(s):  
Nayuta Yamamoto ◽  
Teiji Sota
Keyword(s):  
Sequence Data ◽  
Evolutionary Process ◽  
Fine Tuning ◽  
Colour Pattern ◽  
Tiger Beetle ◽  
Background Matching ◽  
Geographical Populations ◽  
Geographical Distances ◽  
The Japanese Archipelago ◽  
Colour Patterns

Background-matching camouflage is a widespread adaptation in animals; however, few studies have thoroughly examined its evolutionary process and consequences. The tiger beetle Chaetodera laetescripta exhibits pronounced variation in elytral colour pattern among sandy habitats of different colour in the Japanese Archipelago. In this study, we performed digital image analysis with avian vision modelling to demonstrate that elytral luminance, which is attributed to proportions of elytral colour components, is fine-tuned to match local backgrounds. Field predation experiments with model beetles showed that better luminance matching resulted in a lower attack rate and corresponding lower mortality. Using restriction site-associated DNA (RAD) sequence data, we analysed the dispersal and evolution of colour pattern across geographical locations. We found that sand colour matching occurred irrespective of genetic and geographical distances between populations, suggesting that locally adapted colour patterns evolved after the colonization of these habitats. Given that beetle elytral colour patterns presumably have a quantitative genetic basis, our findings demonstrate that fine-tuning of background-matching camouflage to local habitat conditions can be attained through selection by visual predators, as predicted by the earliest proponent of natural selection.

Isolasi Sosio-Budaya Masyarakat Orang Asli di Malaysia dan Kesannya Terhadap Pentafsiran Hukum Islam

2020 ◽  
Vol 21 (1) ◽  
pp. 1-20
Author(s):  
Paiz Hassan ◽  
Mohd Anuar Ramli
Keyword(s):  
Indigenous People ◽  
Indigenous Peoples ◽  
Islamic Law ◽  
Way Of Life ◽  
Low Literacy ◽  
Orang Asli ◽  
Library Research ◽  
Local Background ◽  
Negative Perceptions ◽  
Closed Door

Majority of the indigenous people who are the original inhabitants in Malaysia inhibit the remote area of tropical forest which is rich in natural resources. Their lives are separated from the outside community due to several factors such as geography, low literacy, negative perceptions of the surrounding community, and the closed-door attitude of the indigenous people. Consistent preaching activities have changed the faith of the indigenous people from animism orientation towards believing in the Oneness of God. The practice of Islam as a way of life in the lives of indigenous peoples is found to be difficult to practice because the fiqh approach presented to them does not celebrate their local condition. In this regard, this study will examine the socio-cultural isolation of indigenous peoples and their impact on the interpretation of Islamic law. To achieve this objective, the researchers have applied the library research method by referring to the literatures related to the discussion of Islamic scholars in various disciplines of fiqh and usūl al-fiqh. The research found that there is rukhsah and taysir approach given to isolated people as well as with local background to facilitate the religious affairs of the indigenous people. Abstrak Majoriti masyarakat Orang Asli yang merupakan penduduk asal di semenanjung Malaysia mendiami kawasan pedalaman di hutan hujan tropika yang kaya dengan khazanah alam. Kehidupan mereka terasing daripada masyarakat luar disebabkan beberapa faktor seperti geografi, kadar literasi yang rendah, pandangan negatif masyarakat sekitar dan sikap tertutup masyarakat Orang Asli. Gerakan dakwah yang dijalankan secara konsisten telah membawa perubahan kepercayaan sebahagian masyarakat Orang Asli daripada berorientasikan animisme kepada mempercayai Tuhan yang Esa. Pengamalan Islam sebagai cara hidup dalam kehidupan masyarakat Orang Asli didapati agak sukar untuk dipraktikkan lantaran pendekatan fiqh yang disampaikan kepada mereka tidak meraikan suasana setempat mereka. Sehubungan itu, kajian ini akan meneliti keadaan isolasi sosio-budaya masyarakat Orang Asli dan kesannya terhadap pentafsiran hukum Islam. Bagi mencapai objektif tersebut, pengkaji menggunakan kajian kepustakaan sepenuhnya dengan menelusuri literatur berkaitan dengan perbincangan sarjana Islam dalam pelbagai disiplin ilmu fiqh dan usul fiqh. Hasil kajian mendapati terdapat rukhsah dan pendekatan taysir diberikan kepada mereka yang hidup terasing serta berlatar belakang budaya setempat bagi memudahkan urusan keagamaan masyarakat Orang Asli.

Synthesis

2018 ◽  
Author(s):  
Graeme D. Ruxton ◽  
William L. Allen ◽  
Thomas N. Sherratt ◽  
Michael P. Speed
Keyword(s):  
Background Matching ◽  
First Pass

In writing this new edition, we have thoroughly enjoyed exploring the most recent findings in the fascinating world of anti-predatory interactions and the diverse and sometimes astonishing related adaptations. The first section to this book was devoted to studies of crypsis, beginning with a consideration of background matching. Simply matching the background against which you are seen might seem at first pass to be the be all and end all of avoiding detection. The running theme throughout this chapter, however, is that costs and constraints mean that perfect background matching is often not obtained, and this explains why organisms often utilize other mechanisms of reducing their ease of detection....

Background matching

2018 ◽  
Author(s):  
Graeme D. Ruxton ◽  
William L. Allen ◽  
Thomas N. Sherratt ◽  
Michael P. Speed
Keyword(s):  
Evolutionary Biology ◽  
Complex Environment ◽  
Background Matching ◽  
Highly Effective ◽  
Predation Rates

Background matching is perhaps the most obvious phenomenon that falls under the label of crypsis. Stevens & Merilaita (2011) describe background matching as situations where ‘the appearance generally matches the colour, lightness and pattern of one (specialized) or several (compromise) background types’. There are fascinating examples of species that behaviourally select their microhabitat and orientation so as to enhance similarity to features of the background, and species that change aspects of their appearance in ways that enhance background matching. The degree of background matching is often imperfect; this is thought to commonly reflect the fact that organisms are viewed against a range of different backgrounds, and so they have evolved appearance traits that offer some degree of matching against several of these. Understanding background matching addresses important issues in evolutionary biology, such as the maintenance of polymorphisms. We discuss how predation rates that depend on the frequency of morphs in the environment may be a common explanation for polymorphic crypsis, and the role search images might play in this process. Achieving highly effective background matching in a complex environment is difficult and this may create room for other types of crypsis.

Morphology and diet of two sympatric colubrid snakes, Chironius flavolineatus and Chironius quadricarinatus (Serpentes: Colubridae)

2008 ◽  
Vol 29 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Otavio Augusto Vuolo Marques ◽  
Ronaldo Fernandes ◽  
Roberta Richard Pinto
Keyword(s):  
Foraging Behaviour ◽  
Sexual Size Dimorphism ◽  
Sympatric Species ◽  
Colour Pattern ◽  
Ontogenetic Variation ◽  
Brazilian Cerrado ◽  
Size Dimorphism ◽  
Snake Species ◽  
Dietary Ecology ◽  
Arboreal Habit

Abstract The morphometry and diet of two sympatric species of Chironius (C. flavolineatus and C. quadricarinatus) from Brazilian Cerrado are described. The two snake species differ in external morphology, as Chironius flavolineatus was the largest species (body, tail and eyes) whereas C. quadricarinatus the heaviest. Each species also showed marked sexual size dimorphism. In terms of dietary ecology, both species feed exclusively on frogs with a heavy preference for hylids and may have tendency to eat small items, as noticed in other colubrine species. These two snake species showed a brownish colour pattern and exhibited no ontogenetic variation, suggesting that juveniles and adults use similar substrates. Chironius flavolineatus and C. quadricarinatus present a semi-arboreal habit, with active foraging behaviour, feeding in the ground most of time. Chironius flavolineatus uses higher vegetation for resting and, based on morphological results, seems to be more arboreal than C. quadricarinatus.

scholarly journals Spots and stripes: ecology and colour pattern evolution in butterflyfishes

2013 ◽  
Vol 280 (1757) ◽  
pp. 20122730 ◽  
Author(s):  
Jennifer L. Kelley ◽  
John L. Fitzpatrick ◽  
Sami Merilaita
Keyword(s):  
Colour Pattern
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