Detectable but unseen: imperfect crypsis protects crab spiders from predators

Rodríguez‐Gironés, Miguel A.; Maldonado, Michelle

doi:10.1016/j.anbehav.2020.04.004

Cited by 8 publications

(5 citation statements)

References 40 publications

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“…The flowers of Serapias function as a refuge for some bee species such as Eucera , Andrena , Osmia , and Tetralonia that also act as pollinators (Bellusci et al, 2009). In this specialized pollination system, a high floral conspicuousness would be disadvantageous for the pollinator, as the shelter would be easily detectable by predators (Rodríguez‐Gironés & Maldonado, 2020). In fact, Serapias orchids seem to attract pollinators using olfactory signals (Kantsa et al, 2017; Vereecken et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators

León‐Osper

Narbona

2022

Functional Ecology

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Red‐flowered species have traditionally been related to ornithophily, and the ‘bee avoidance’ hypothesis, that is, red flower colouration is a way to reduce visits from hymenopterans, has been proposed to explain this association. In the Mediterranean Basin, ornithophily is almost absent, and hymenopterans are the most common group of pollinators. The fact that hymenopterans are virtually red‐blind raises the question of how red‐flowered species are pollinated in this region. Are these flowers pollinated by other groups of red‐sensitive insects such as lepidopterans and coleopterans, or do they have visual cues that make them attractive to hymenopterans? We examined the reflectance spectra of 51 red‐flowered species from the Mediterranean Basin and modelled these spectra in the visual system of hymenopterans, dipterans, coleopterans and lepidopterans to obtain colour and conspicuousness. According to their reflectance curves, species were classified as pure red and UV‐red flowers, and the presence of more than one flower colour (patterned flowers) was studied. We evaluated the match between flower reflectance spectra and the maximum discrimination abilities of hymenopteran and lepidopteran visual system. All these metrics were analysed in a phylogenetically explicit framework, and a literature review of potential pollinators was performed. The vast majority of red‐flowered species in the Mediterranean Basin are potentially pollinated by hymenopterans, and only three species are exclusively visited by coleopterans. We found that 90% of these species showed at least one colour signal strategy that helps to enhance conspicuousness to hymenopterans: to produce UV‐red flower type spectra and/or patterned flowers. The UV‐red colour showed a significant phylogenetic signal, but the presence of patterned flowers did not. Even though the red‐flowered species of the Mediterranean Basin did not optimally match the colour vision of hymenopterans or lepidopterans, the presence of patterned and UV‐red colours suggests an improvement in detection and discrimination by hymenopterans. The bee‐avoidance hypothesis seems to be ruled out for the red‐flowered species of the Mediterranean Basin. Our results suggest that red‐flowered species are mostly pollinated by hymenopterans and show different flower colour signal strategies that can be interpreted as signs of adaptation to these pollinators. Read the free Plain Language Summary for this article on the Journal blog.

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Section: Discussionmentioning

confidence: 99%

Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators

León‐Osper

Narbona

2022

Functional Ecology

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“…New methods for quantifying camouflage and the similarity between prey animals and their natural habitats, from the perspective of potential predators, have shown that many species are locally adapted to specific backgrounds ( Harris and Weatherall 1991 ; Boratyński et al 2014 ; Marshall et al 2015 ; Niu et al 2017 ; Yamamoto and Sota 2020 ), and that these small improvements in background matching can have beneficial effects on survival ( Troscianko et al 2016 ). Yet, despite the difficulty of conclusively demonstrating that natural color patterns operate as generalists ( Cuthill 2019 ), putative generalist morphs are thought to exist in several species, including shrimp ( Duarte et al 2016 ), crabs ( Nokelainen et al 2019 ), and skinks ( Baling et al 2020 ), and there is evidence that imperfect camouflage can provide some protection from observers (Nokelainen et al 2019 , 2020 ; Rodríguez-Gironés and Maldonado 2020 ; Barnett et al 2021 ). In turn, empirical tests using artificial setups of the effectiveness of generalist and specialist strategies in nonhuman animals broadly support the predictions of theoretical models, suggesting that compromise patterns can be successful, and that their relative benefits depend on background similarity ( Merilaita et al 2001 ; Bond and Kamil 2006 ).…”

Section: Introductionmentioning

confidence: 99%

Varying benefits of generalist and specialist camouflage in two versus four background environments

et al. 2023

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Background-matching camouflage is a well-established strategy to reduce detection, but implementing this on heterogeneous backgrounds is challenging. For prey with fixed color patterns, solutions include specializing on a particular visual microhabitat, or adopting a compromise or generalist appearance, matching multiple backgrounds less well. Existing studies suggest both approaches can succeed, but most consider relatively simple scenarios, where artificial prey appear against two backgrounds differing in a single visual characteristic. Here, we used computer-based search tasks with human participants to test the relative benefits of specializing and generalizing for complex targets, displayed on either two or four types of naturalistic backgrounds. Across two background types, specialization was beneficial on average. However, the success of this strategy varied with search duration, such that generalist targets could outperform specialists over short search durations due to the presence of poorly matched specialists. Over longer searches, the remaining well-matched specialists had greater success than generalists, leading to an overall benefit of specialization at longer search durations. Against four different backgrounds, the initial cost to specialization was greater, so specialists and generalists ultimately experienced similar survival. Generalists performed better when their patterning was a compromise between backgrounds that were more similar to each other than when backgrounds were more different, with similarity in luminance more relevant than pattern differences. Time dependence in the relative success of these strategies suggests that predator search behavior may affect optimal camouflage in real-world situations.

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“…CC-BY-NC 4.0 International license available under a (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made The copyright holder for this preprint this version posted March 22, 2021. ; https://doi.org/10.1101/2021.03.20.436281 doi: bioRxiv preprint How dune wasps avoid attack -DRM et al 4 their risk of predation by birds (Rodríguez-Gironés and Maldonado, 2020). Though some crab spiders can increase the number of potential pollinators approaching the flower using deceptive signalling that exploit an insect's ability to perceive UV colouration (Heiling et al, 2003;Llandres and Rodríguez-Gironés, 2011;Vieira et al, 2017), several studies have shown that the presence of a spider on a flower deters pollinators (Robertson and Maguire, 2005;Yokoi and Fujisaki, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…However, there is still controversy whether the intended receivers of the crypsis are prey or predators. Crypsis was found to be ineffective when considering the entire community of flower visiting potential prey (Brechbuhl et al, 2010) and a recent study argued that crypsis in crab spiders reduce their risk of predation by birds (Rodríguez-Gironés and Maldonado, 2020). Though some crab spiders can increase the number of potential pollinators approaching the flower using deceptive signalling that exploit an insect’s ability to perceive UV colouration (Heiling et al, 2003; Llandres and Rodríguez-Gironés, 2011; Vieira et al, 2017), several studies have shown that the presence of a spider on a flower deters pollinators (Robertson and Maguire, 2005; Yokoi and Fujisaki, 2008).…”

Section: Introductionmentioning

confidence: 99%

Avoiding attack: How dune wasps leverage colour and motion to detect their cryptic spider predators

Rodríguez-Morales

Tapia-McClung

et al. 2021

Preprint

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Ambush predators depend on cryptic body colouration, stillness and a suitable hunting location to optimise the probability of prey capture. Detection of cryptic predators, such as crab spiders, by flower seeking wasps may also be hindered by wind induced movement of the flowers themselves. In a beach dune habitat, as Microbembex nigrifrons wasps approach flowerheads of the Palafoxia lindenii plant, they need to evaluate the flowers and avoid landing on crab spider occupied flowers. Wasps may detect spiders through colour and movement cues. We tracked the flight trajectories of dune wasps as they approached occupied and unoccupied flowers under two movement conditions; when the flowers were still or moving. We simulated the appearance of the spider and the flower using psychophysical visual modelling techniques and related it to the decisions made by the wasp to land or avoid the flower. Wasps could discriminate spiders only at a very close range, and this was reflected in the shape of their trajectories. Wasps were more prone to making errors in threat assessment when the flowers are moving. Our results suggest that dune wasp predation risk is augmented by abiotic conditions such as wind and compromises their early detection capabilities.

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Detectable but unseen: imperfect crypsis protects crab spiders from predators

Cited by 8 publications

References 40 publications

Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators

Unravelling the mystery of red flowers in the Mediterranean Basin: How to be conspicuous in a place dominated by hymenopteran pollinators

Varying benefits of generalist and specialist camouflage in two versus four background environments

Avoiding attack: How dune wasps leverage colour and motion to detect their cryptic spider predators

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