Tadpoles respond to background colour under threat

Mendes, Izabela Santos; Kloh, Jéssica Stephanie; Pinheiro, Luan Tavares; Václav, Amadeus Bicalho Horta Portela; Santos, Thiago; Gontijo, Ana Sofia Buza

doi:10.1038/s41598-018-22315-8

Cited by 20 publications

(14 citation statements)

References 29 publications

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“…The exception was that individuals already close to shelter (leaves, rocks, and other refuges) often chose to escape to cover. More recent work on the tadpole Ololygon machadoi shows that individuals prefer light‐yellow backgrounds over dark or blue ones, possibly as this facilitates disruptive camouflage with their dark bodies and yellow barred markings (Eterovick et al, ). However, this seems to be a species‐level choice and the situation in other species is less clear.…”

Section: Background Choicementioning

confidence: 99%

The key role of behaviour in animal camouflage

2018

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Animal camouflage represents one of the most important ways of preventing (or facilitating) predation. It attracted the attention of the earliest evolutionary biologists, and today remains a focus of investigation in areas ranging from evolutionary ecology, animal decision-making, optimal strategies, visual psychology, computer science, to materials science. Most work focuses on the role of animal morphology per se, and its interactions with the background in affecting detection and recognition. However, the behaviour of organisms is likely to be crucial in affecting camouflage too, through background choice, body orientation and positioning; and strategies of camouflage that require movement. A wealth of potential mechanisms may affect such behaviours, from imprinting and self-assessment to genetics, and operate at several levels (species, morph, and individual). Over many years there have been numerous studies investigating the role of behaviour in camouflage, but to date, no effort to synthesise these studies and ideas into a coherent framework. Here, we review key work on behaviour and camouflage, highlight the mechanisms involved and implications of behaviour, discuss the importance of this in a changing world, and offer suggestions for addressing the many important gaps in our understanding of this subject.

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Section: Background Choicementioning

confidence: 99%

The key role of behaviour in animal camouflage

2018

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“…Different types of camouflage (i.e., masquerade, disruptive and distractive coloration, surface disruption and countershading) are generated by a combination of skin patterns and colours selected through evolution in many prey and predator species as a means to reduce the likelihood of detection (crypsis) (Skelhorn & Rowe, ). In general, they are not mutually exclusive and work best when several of their components match the background colour (Eterovick et al, ). The matching of skin pigmentation to background colour can be genetically determined (defined here as “background matching”), or induced by physiological plasticity through differential secretion of hormones by neuroendocrine systems (“background adaptation”) (Baker & Bird, ; Hoekstra, ).…”

Section: Introductionmentioning

confidence: 99%

Plasticity for colour adaptation in vertebrates explained by the evolution of the genes pomc, pmch and pmchl

Bertolesi

Zhang

McFarlane

2019

Pigment Cell Melanoma Res

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Different camouflages work best with some background matching colour. Our understanding of the evolution of skin colour is based mainly on the genetics of pigmentation (“background matching”), with little known about the evolution of the neuroendocrine systems that facilitate “background adaptation” through colour phenotypic plasticity. To address the latter, we studied the evolution in vertebrates of three genes, pomc, pmch and pmchl, that code for α‐MSH and two melanin‐concentrating hormones (MCH and MCHL). These hormones induce either dispersion/aggregation or the synthesis of pigments. We find that α‐MSH is highly conserved during evolution, as is its role in dispersing/synthesizing pigments. Also conserved is the three‐exon pmch gene that encodes MCH, which participates in feeding behaviours. In contrast, pmchl (known previously as pmch), is a teleost‐specific intron‐less gene. Our data indicate that in zebrafish, pmchl‐expressing neurons extend axons to the pituitary, supportive of an MCHL hormonal role, whereas zebrafish and Xenopus pmch+ neurons send axons dorsally in the brain. The evolution of these genes and acquisition of hormonal status for MCHL explain different mechanisms used by vertebrates to background‐adapt.

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“…3), what may reinforce the protective effect of camouflage. Innate preferences are likely to influence on the results of learning processes 20 , and an innate (or learned) preference for yellow backgrounds seems to prevail in tadpoles of O. machadoi 17 . When moving towards yellow backgrounds, the tadpoles may be more likely to express immobility if they have an innate or learned ability to associate yellow backgrounds with protection (through camouflage).…”

Section: Discussionmentioning

confidence: 99%

“…Results that differed significantly are indicated by different letters. www.nature.com/scientificreports/ positioning themselves preferentially on yellow backgrounds where they are disruptive 17,18 . Ololygon machadoi breeds year-round in many streams in the RPPN, and we used one of these streams (20 o 05′37″S, 43 o 29′59″W; 1293 m above sea level), where its tadpoles are abundant, to conduct the experiments.…”

Section: Study Site Experiments Were Conducted In the Reserva Particmentioning

confidence: 99%

“…The treefrog Ololygon machadoi has conspicuously coloured larvae: especially the young tadpoles have a dark brown body with an anterior and a posterior transversal yellow band, and this pattern is expected to be disruptive on yellowish backgrounds 17 . In laboratory experiments, these tadpoles increased the use of yellow backgrounds in the presence of visual and/or chemical cues of water bugs (Belostoma testaceopallidum Latreille, 1807) 18 , but did not show decreased movement as would be expected in association with background matching 3 .…”

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confidence: 99%

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Background choice and immobility as context dependent tadpole responses to perceived predation risk

Kloh

Figueredo

Viana

et al. 2020

Sci Rep

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The association of immobility and camouflage is widespread as a defensive mechanism in prey from varied taxa. However, many experiments assessing the reaction of prey to predator cues are conducted under artificial laboratory conditions. In a previous experiment we observed the tadpoles of Ololygon machadoi (Hylidae) to respond to predator visual and/or chemical cues by choosing backgrounds that improve their disruptive properties, but detected no associated reduction of movement. Here we experimentally demonstrate this response in the species' natural habitat, on backgrounds where the tadpoles are likely to achieve their best camouflage. We also tested whether previous experiences could influence both background choice and immobility in O. machadoi tadpoles. these novel experimental results suggest that a defensive behavior-i.e., reduction of movement-in these tadpoles is more strongly expressed under the natural conditions where they evolved, compared to laboratory conditions where prey and predator were brought into closer contact. Besides, previous experiences are likely to play an important role in expressed defensive responses. Prey species are under constant selection to escape predation. They can develop predator specific responses, but some responses seem to be widespread, such as spatial avoidance of predators and reduction of activity 1. In this context prey species that count on camouflage to reduce the probability of being detected by predators tend to remain motionless, aiding to the protective properties of their colouration 2,3. Reduction of movement is likely to reduce detection probability and can emerge as a spontaneous response when the detected threat is at a distance (background threat), but an approaching (immediate) threat may otherwise elicit an escape response 4. Previous experience can also determine the reaction of prey to specific predators 5 , however there is evidence that evolutionary pressures may have led prey species to develop different defensive mechanisms and express each one in appropriate contexts determined by the assessed threat 4. Both innate and learned defensive behaviours can be expressed even in very early life stages 6,7. Tadpoles, the larvae of biphasic anuran amphibians, are frequently employed in experiments conducted to study the reaction of prey to predator cues 8 , due to their broad range of predators and defensive mechanisms 1. It has been shown that many species of tadpoles reduce movement in the presence of predators 1,9. However, these studies are usually conducted under laboratory or mesocosm conditions, sometimes within reduced spaces in artificial standardized containers where predator cues are manipulated, other factors kept equal, to record tadpole reaction to particular cues 1,10. Under such circumstances, both visual and chemical stimuli have been

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Tadpoles respond to background colour under threat

Cited by 20 publications

References 29 publications

The key role of behaviour in animal camouflage

The key role of behaviour in animal camouflage

Plasticity for colour adaptation in vertebrates explained by the evolution of the genes pomc, pmch and pmchl

Background choice and immobility as context dependent tadpole responses to perceived predation risk

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