Birds learn to avoid aposematic prey by using the appearance of host plants

McLellan, Callum F.; Scott‐Samuel, Nicholas E.; Cuthill, Innes C.

doi:10.1016/j.cub.2021.09.048

Cited by 11 publications

(7 citation statements)

References 36 publications

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“…Species with reduced predation pressure may be able to thermoregulate more freely. Of the species tested, T. jacobaeae is the only aposematically coloured larva, and is chemically defended from predation (McLellan et al., 2021 ). Because of this, larvae of this species tends to be active—feeding or basking openly—during the day (Dempster, 1982 ).…”

Section: Discussionmentioning

confidence: 99%

Day‐flying lepidoptera larvae have a poorer ability to thermoregulate than adults

Ashe‐Jepson,

Hayes,

Hitchcock

et al. 2023

Ecology and Evolution

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Changes to ambient temperatures under climate change may detrimentally impact small ectotherms that rely on their environment for thermoregulation; however, there is currently a limited understanding of insect larval thermoregulation. As holometabolous insects, Lepidoptera differ in morphology, ecology and behaviour across the life cycle, and so it is likely that adults and larvae differ in their capacity to thermoregulate. In this study, we investigated the thermoregulatory capacity (buffering ability) of 14 species of day‐flying Lepidoptera, whether this is influenced by body length or gregariousness, and whether it differs between adult and larval life stages. We also investigated what thermoregulation mechanisms are used: microclimate selection (choosing locations with a particular temperature) or behavioural thermoregulation (controlling temperature through other means, such as basking). We found that Lepidoptera larvae differ in their buffering ability between species and body lengths, but gregariousness did not influence buffering ability. Larvae are worse at buffering themselves against changes in air temperature than adults. Therefore Lepidoptera may be more vulnerable to adverse temperature conditions during their larval life stage. Adults and larvae rely on different thermoregulatory mechanisms; adults primarily use behavioural thermoregulation, whereas larvae use microclimate selection. This implies that larvae are highly dependent on the area around their foodplant for effective thermoregulation. These findings have implications for the management of land and species, for example, highlighting the importance of creating and preserving microclimates and vegetation complexity surrounding Lepidoptera foodplants for larval thermoregulation under future climate change.

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Section: Discussionmentioning

confidence: 99%

Day‐flying lepidoptera larvae have a poorer ability to thermoregulate than adults

Ashe‐Jepson,

Hayes,

Hitchcock

et al. 2023

Ecology and Evolution

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“…In recent papers employing the MICA toolbox, it is often not explicitly stated whether the authors used the newly‐introduced chart method or the library of natural spectra to train their statistical filters (Barnett et al., 2021; Cueva Del Castillo et al., 2021; McLellan et al., 2021; Wuthrich et al., 2022). The paper may mention that a colour chart was included in the photographs, but it can be unclear whether the authors simply used the greys on the chart to linearize and colour balance the photograph, or whether they used the entire chart for photoreceptor mapping.…”

Section: Discussionmentioning

confidence: 99%

A comparison of photographic and spectrometric methods to quantify the colours seen by animal eyes

Tedore

2023

Methods Ecol Evol

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Quantifying how colours stimulate animal eyes is an essential first step in many areas of biology, from behavioural and visual ecology to neuroethology. Although multiple methods exist, their relative accuracies remain untested, leaving researchers unsure which methods are most accurate and which might be unacceptably inaccurate. Here, I compare measurements from reflectance spectrometry and four camera‐based techniques to ground‐truth spectroradiometric measurements of radiance, using eight diverse visual systems. Because errors may compound through successive calculations, I calculate not only relative quantum catches but also chroma and colour contrasts. I find that filters mimicking photoreceptor spectral sensitivity curves, through either custom fabrication or weighted additive combinations of bandpass filters (‘computational filters’), as well as reflectance spectrometry, are the most accurate techniques, with most R2 > 0.98. Statistical filters trained on the library of reflectance spectra in the multispectral image calibration and analysis (MICA) toolbox lag behind in accuracy, particularly for dark colours, with R2 values dipping as low as 0.23. However, the performance of these filters is vastly improved (all R2 > 0.96) if one (a) uses the full UV–VIS range of camera and animal vision, even for animals lacking UV photoreceptors and (b) expands the library of training spectra to include simulated low‐reflectance spectra. Statistical filters trained on either a 24‐ or 45‐colour chart (an alternative method offered by the MICA toolbox) vary wildly in accuracy, with R2 values ranging from 0.11 to 0.94, and should not be trusted. For those requiring point measurements only, reflectance spectrometry is highly accurate within the constraints described in the main text. Those using photography and desiring the highest levels of accuracy should opt for custom‐fabricated or computational filters. Statistical filters trained on the MICA toolbox's library of natural spectra can be expected to be reasonably accurate for many combinations of visual systems and stimuli, but only if (a) the full UV–VIS spectrum is used and (b) the training library is expanded to include simulated low‐reflectance spectra. Statistical filters trained on a colour chart are highly unreliable and their use should be discontinued.

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“…We followed an established, stepwise model selection process (e.g. in McLellan et al 2021) beginning with the initial saturated model containing individual platform ID and experimental block number as random effects, and target color (two levels: cryptic and aposematic), group size (two levels: solitary (1) and grouped (15)), background color (two levels: green and white) and body size (three levels: small, medium and large) as fixed effects. Block was not significant, so all subsequent models only contained platform ID as a random effect.…”

Section: Methodsmentioning

confidence: 99%

Warning coloration, body size and the evolution of gregarious behavior in butterfly larvae

McLellan

Montgomery

Cuthill

2022

Preprint

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Many species gain anti-predator benefits by combining gregarious behavior with warning coloration, yet there is debate over which trait evolves first, and which is the secondary adaptive enhancement. Body size can also influence how predators receive aposematic signals, and potentially constrain the evolution of gregarious behavior. To our knowledge, the causative links between the evolution of gregariousness, aposematism and larger body sizes have not been fully resolved. Here, using the most recently resolved butterfly phylogeny and an extensive new dataset of larval traits, we reveal the evolutionary interactions between important traits linked to larval gregariousness. We show that larval gregariousness has arisen many times across the butterflies, and aposematism is a likely prerequisite for gregariousness to evolve. We also find that body size may be an important factor for determining the coloration of solitary, but not gregarious larvae. Additionally, by exposing artificial 'larvae' to wild avian predation, we show that undefended, cryptic 'larvae' are heavily predated when aggregated but benefit from solitariness, whereas the reverse is true for aposematic prey. Our data reinforce the importance of aposematism for gregarious larval survival, whilst identifying new questions about the roles of body size and toxicity in the evolution of grouping behavior.

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Birds learn to avoid aposematic prey by using the appearance of host plants

Cited by 11 publications

References 36 publications

Day‐flying lepidoptera larvae have a poorer ability to thermoregulate than adults

Day‐flying lepidoptera larvae have a poorer ability to thermoregulate than adults

A comparison of photographic and spectrometric methods to quantify the colours seen by animal eyes

Warning coloration, body size and the evolution of gregarious behavior in butterfly larvae

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