scholarly journals Hard to catch: experimental evidence supports evasive mimicry

2021 ◽  
Vol 288 (1946) ◽  
pp. 20203052
Author(s):  
Erika Páez ◽  
Janne K. Valkonen ◽  
Keith R. Willmott ◽  
Pável Matos-Maraví ◽  
Marianne Elias ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Empirical Evidence ◽  
Attack Rate ◽  
Colour Pattern ◽  
Wing Colour ◽  
Morphological Convergence ◽  
Wing Patterns ◽  
Colour Patterns ◽  
Blue Tits ◽  
Candidate Group

Most research on aposematism has focused on chemically defended prey, but the signalling difficulty of capture remains poorly explored. Similar to classical Batesian and Müllerian mimicry related to distastefulness, such ‘evasive aposematism' may also lead to convergence in warning colours, known as evasive mimicry. A prime candidate group for evasive mimicry areAdelphabutterflies, which are agile insects and show remarkable colour pattern convergence. We tested the ability of naive blue tits to learn to avoid and generalizeAdelphawing patterns associated with the difficulty of capture and compared their response to that of birds that learned to associate the same wing patterns with distastefulness. Birds learned to avoid all wing patterns tested and generalized their aversion to other prey to some extent, but learning was faster with evasive prey compared to distasteful prey. Our results on generalization agree with longstanding observations of striking convergence in wing colour patterns amongAdelphaspecies, since, in our experiments, perfect mimics of evasive and distasteful models were always protected during generalization and suffered the lowest attack rate. Moreover, generalization on evasive prey was broader compared to that on distasteful prey. Our results suggest that being hard to catch may deter predators at least as effectively as distastefulness. This study provides empirical evidence for evasive mimicry, a potentially widespread but poorly understood form of morphological convergence driven by predator selection.

scholarly journals Hard to catch: Experimental evidence supports evasive mimicry

2020 ◽  
Author(s):  
Erika Páez V ◽  
Janne K. Valkonen ◽  
Keith R. Willmott ◽  
Pável Matos-Maraví ◽  
Marianne Elias ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Empirical Evidence ◽  
Avoidance Learning ◽  
Colour Pattern ◽  
Alternative Scenario ◽  
Wing Patterns ◽  
Selection For ◽  
Colour Patterns ◽  
Blue Tits ◽  
Candidate Group

ABSTRACTMost research on aposematism has focused on chemically defended prey, but signalling difficulty of capture remains poorly explored. Similarly to classical Batesian and Müllerian mimicry related to distastefulness, such “evasive aposematism” may also lead to convergence in warning colours, known as evasive mimicry. A prime candidate group for evasive mimicry are Adelpha butterflies, which are agile insects and show remarkable colour pattern convergence. We tested the ability of naïve blue tits to learn to avoid and generalise Adelpha wing patterns associated with difficulty of capture, and compared their response to that of birds that learned to associate the same wing patterns with distastefulness. Birds learned to avoid all wing patterns tested, but learning was faster with evasive prey compared with distasteful prey. Birds generalised their learned avoidance from evasive models to imperfect mimics if the mimic shared colours with the model. Despite imperfect mimics gaining protection from bird’s generalisation, perfect mimics always had the best fitness, supporting selection for accurate mimicry. Faster avoidance learning and broader generalisation of evasive prey suggest that being hard to catch may deter predators at least as effectively as distastefulness. Our results provide empirical evidence for a potentially widespread alternative scenario, evasive mimicry, for the evolution of similar aposematic colour patterns.

scholarly journals Disruptive ecological selection on a mating cue

2012 ◽  
Vol 279 (1749) ◽  
pp. 4907-4913 ◽  
Author(s):  
Richard M. Merrill ◽  
Richard W. R. Wallbank ◽  
Vanessa Bull ◽  
Patricio C. A. Salazar ◽  
James Mallet ◽  
...  
Keyword(s):  
Field Experiments ◽  
Random Mating ◽  
Experimental Manipulation ◽  
Colour Pattern ◽  
Disruptive Selection ◽  
Ecological Niches ◽  
Ecological Selection ◽  
Wing Patterns ◽  
Colour Patterns ◽  
First Time

Adaptation to divergent ecological niches can result in speciation. Traits subject to disruptive selection that also contribute to non-random mating will facilitate speciation with gene flow. Such ‘magic’ or ‘multiple-effect’ traits may be widespread and important for generating biodiversity, but strong empirical evidence is still lacking. Although there is evidence that putative ecological traits are indeed involved in assortative mating, evidence that these same traits are under divergent selection is considerably weaker. Heliconius butterfly wing patterns are subject to positive frequency-dependent selection by predators, owing to aposematism and Müllerian mimicry, and divergent colour patterns are used by closely related species to recognize potential mates. The amenability of colour patterns to experimental manipulation, independent of other traits, presents an excellent opportunity to test their role during speciation. We conducted field experiments with artificial butterflies, designed to match natural butterflies with respect to avian vision. These were complemented with enclosure trials with live birds and real butterflies. Our experiments showed that hybrid colour-pattern phenotypes are attacked more frequently than parental forms. For the first time, we demonstrate disruptive ecological selection on a trait that also acts as a mating cue.

scholarly journals Classic and introgressed selective sweeps shape mimicry loci across a butterfly adaptive radiation

2019 ◽  
Author(s):  
Markus Moest ◽  
Steven M. Van Belleghem ◽  
Jennifer E. James ◽  
Camilo Salazar ◽  
Simon H. Martin ◽  
...  
Keyword(s):  
Adaptive Radiation ◽  
Sequence Data ◽  
Colour Pattern ◽  
Stabilizing Selection ◽  
High Coverage ◽  
Adaptive Introgression ◽  
Wing Patterns ◽  
History Of ◽  
Colour Patterns ◽  
Turn Over

AbstractNatural selection leaves distinct signatures in the genome that can reveal the targets and history of adaptive evolution. By analysing high-coverage genome sequence data from four major colour pattern loci sampled from nearly 600 individuals in 53 populations, we show pervasive selection on wing patterns across the Heliconius adaptive radiation. The strongest signatures correspond to loci with the greatest phenotypic effects, consistent with visual selection by predators, and are found in colour patterns with geographically restricted distributions. These recent sweeps are similar between co-mimics and indicate colour pattern turn-over events despite strong stabilizing selection. Using simulations we compare sweep signatures expected under classic hard sweeps with those resulting from adaptive introgression, an important aspect of mimicry evolution in Heliconius. Simulated recipient populations show a distinct ‘volcano’ pattern with peaks of increased genetic diversity around the selected target, consistent with patterns found in some populations. Our genomic data provide unprecedented insights into the recent history of selection across the Heliconius adaptive radiation.

Colour pattern modification by coldshock in Lepidoptera

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 287-305
Author(s):  
H. Frederik Nijhout
Keyword(s):  
Colour Pattern ◽  
Gradient System ◽  
Experimental Animals ◽  
Vanessa Cardui ◽  
Adult Wing ◽  
Wing Patterns ◽  
Pattern Determination ◽  
Colour Patterns ◽  
Precis Coenia ◽  
Morphological Series

When young pupae of Vanessa cardui, V. virginiensis and Precis coenia (Lepidoptera: Nymphalidae) are exposed to severe coldshock many develop aberrant adult wing patterns. For each species, a synchronous cohort of experimental animals always develops a broad range of aberrant pattern morphologies but these can always be arranged in a single unbranched morphological series. When such phenotypic series are compared, between species and between wing surfaces within a species (each wing surface usually bears a different colour pattern), many parallel modifications and trends become evident. These parallelisms reveal certain homologies of pattern elements and suggest that a common physiology underlies the development of a considerable diversity of normal and aberrant colour patterns. The case is made that the phenotypic series produced may represent either a series of sequential stages in colour pattern determination or, a series of quantitatively different ‘interpretations’ of an established gradient system. Colour pattern morphoclines reveal which patterns are developmentally ‘adjacent’ to one another and may therefore prove useful in elucidating the evolution of patterns.

scholarly journals The evolution and genetics of sexually dimorphic ‘dual’ mimicry in the butterfly Elymnias hypermnestra

2021 ◽  
Vol 288 (1942) ◽  
pp. 20202192
Author(s):  
Dee M. Ruttenberg ◽  
Nicholas W. VanKuren ◽  
Sumitha Nallu ◽  
Shen-Horn Yen ◽  
Djunijanti Peggie ◽  
...  
Keyword(s):  
Sexual Dimorphism ◽  
Population Genomics ◽  
Model Organism ◽  
Single Species ◽  
Species Tree ◽  
Colour Pattern ◽  
Nucleotide Polymorphisms ◽  
Wing Colour ◽  
Population Structure Analysis ◽  
Colour Patterns

Sexual dimorphism is a major component of morphological variation across the tree of life, but the mechanisms underlying phenotypic differences between sexes of a single species are poorly understood. We examined the population genomics and biogeography of the common palmfly Elymnias hypermnestra , a dual mimic in which female wing colour patterns are either dark brown (melanic) or bright orange, mimicking toxic Euploea and Danaus species, respectively. As males always have a melanic wing colour pattern, this makes E. hypermnestra a fascinating model organism in which populations vary in sexual dimorphism. Population structure analysis revealed that there were three genetically distinct E. hypermnestra populations, which we further validated by creating a phylogenomic species tree and inferring historical barriers to gene flow. This species tree demonstrated that multiple lineages with orange females do not form a monophyletic group, and the same is true of clades with melanic females. We identified two single nucleotide polymorphisms (SNPs) near the colour patterning gene WntA that were significantly associated with the female colour pattern polymorphism, suggesting that this gene affects sexual dimorphism. Given WntA 's role in colour patterning across Nymphalidae, E. hypermnestra females demonstrate the repeatability of the evolution of sexual dimorphism.

Perspectives

2017 ◽  
Author(s):  
Armin Schnider
Keyword(s):  
Experimental Investigation ◽  
Experimental Evidence ◽  
Empirical Evidence ◽  
False Memories ◽  
Experimental Basis ◽  
The Relationship ◽  
Scientific Standards

This chapter summarizes current interpretations of all forms of confabulations discussed in the book and reviews the relationship between the four forms of memory-related confabulations. Experimental investigation has confirmed the dissociation between various types of false memories and considerably advanced the understanding of the mechanisms of some forms of confabulation, in particular behaviourally spontaneous confabulation and false statements in anosognosia. Overall, experimental evidence is scarce; many models have no controlled experimental basis or extend their proposed range of application well beyond the empirical evidence. The chapter concludes with a call for heightened respect of basic scientific standards in the research on confabulation.

scholarly journals Dog colour patterns explained by modular promoters of ancient canid origin

2021 ◽  
Author(s):  
Danika L. Bannasch ◽  
Christopher B. Kaelin ◽  
Anna Letko ◽  
Robert Loechel ◽  
Petra Hug ◽  
...  
Keyword(s):  
Colour Pattern ◽  
Hair Cycle ◽  
Temporal And Spatial Distribution ◽  
Multiple Alleles ◽  
Haplotype Combination ◽  
Regulatory Modules ◽  
Regulatory Module ◽  
Temporal And Spatial ◽  
Selection For ◽  
Colour Patterns

AbstractDistinctive colour patterns in dogs are an integral component of canine diversity. Colour pattern differences are thought to have arisen from mutation and artificial selection during and after domestication from wolves but important gaps remain in understanding how these patterns evolved and are genetically controlled. In other mammals, variation at the ASIP gene controls both the temporal and spatial distribution of yellow and black pigments. Here, we identify independent regulatory modules for ventral and hair cycle ASIP expression, and we characterize their action and evolutionary origin. Structural variants define multiple alleles for each regulatory module and are combined in different ways to explain five distinctive dog colour patterns. Phylogenetic analysis reveals that the haplotype combination for one of these patterns is shared with Arctic white wolves and that its hair cycle-specific module probably originated from an extinct canid that diverged from grey wolves more than 2 million years ago. Natural selection for a lighter coat during the Pleistocene provided the genetic framework for widespread colour variation in dogs and wolves.

scholarly journals Oversized Area Indications on Bonus Packs Fail to Affect Consumers’ Transactional Decisions—More Experimental Evidence on the Mars Case

2021 ◽  
Author(s):  
K. P. Purnhagen ◽  
E. van Herpen ◽  
S. Kamps ◽  
F. Michetti
Keyword(s):  
Experimental Evidence ◽  
Empirical Evidence ◽  
Current Paper ◽  
Legal Interpretation ◽  
Eu Legislation ◽  
Behavioural Research ◽  
Actual Choice ◽  
Unfair Commercial Practices Directive ◽  
Legal Sense ◽  
The Way

AbstractFindings from behavioural research are gaining increased interest in EU legislation, specifically in the area of unfair commercial practices. Prior research on the Mars case (Purnhagen and van Herpen 2017) has left open whether empirical evidence can provide an indication that this practice of using oversized indications of additional volume alters the transactional decision of consumers. This, however, is required to determine the “misleadingness” of such a practice in the legal sense as stipulated by the Unfair Commercial Practices Directive 2005/29/EC. The current paper closes this gap by illustrating how behavioural research can inform legal interpretation. In particular, it extends the previous research in two important ways: first, by examining the actual choice that people make; and second, by investigating whether the effects remain present in a context where a comparison product is available. Yet, while supporting and extending the findings of the study from Purnhagen and van Herpen (2017) on deceptiveness, the current study could not produce empirical evidence of a clear influence on the transactional decision of consumers, in the way “UCPD” requires.

scholarly journals Female butterflies prefer males bearing bright iridescent ornamentation

2007 ◽  
Vol 274 (1613) ◽  
pp. 1043-1047 ◽  
Author(s):  
Darrell J Kemp
Keyword(s):  
Mate Choice ◽  
Driving Force ◽  
Female Mate Choice ◽  
Sex Recognition ◽  
Female Mate ◽  
Wing Colour ◽  
Enclosure Experiments ◽  
Colour Patterns

Butterflies are among nature's most colourful animals, and provide a living showcase for how extremely bright, chromatic and iridescent coloration can be generated by complex optical mechanisms. The gross characteristics of male butterfly colour patterns are understood to function for species and/or sex recognition, but it is not known whether female mate choice promotes visual exaggeration of this coloration. Here I show that females of the sexually dichromatic species Hypolimnas bolina prefer conspecific males that possess bright iridescent blue/ultraviolet dorsal ornamentation. In separate field and enclosure experiments, using both dramatic and graded wing colour manipulations, I demonstrate that a moderate qualitative reduction in signal brightness and chromaticity has the same consequences as removing the signal entirely. These findings validate a long-held hypothesis, and argue for the importance of intra- versus interspecific selection as the driving force behind the exaggeration of bright, iridescent butterfly colour patterns.

scholarly journals Experimental evidence for friction-enhancing integumentary modifications of chameleons and associated functional and evolutionary implications

2014 ◽  
Vol 281 (1775) ◽  
pp. 20132334 ◽  
Author(s):  
Eraqi R. Khannoon ◽  
Thomas Endlein ◽  
Anthony P. Russell ◽  
Kellar Autumn
Keyword(s):  
Experimental Evidence ◽  
Frictional Coefficient ◽  
Force Transducer ◽  
Morphological Convergence ◽  
Functional Implications ◽  
Smooth Skin ◽  
Derivatives Of

The striking morphological convergence of hair-like integumentary derivatives of lizards and arthropods (spiders and insects) demonstrates the importance of such features for enhancing purchase on the locomotor substrate. These pilose structures are responsible for the unique tractive abilities of these groups of animals, enabling them to move with seeming ease on overhanging and inverted surfaces, and to traverse inclined smooth substrates. Three groups of lizards are well known for bearing adhesion-promoting setae on their digits: geckos, anoles and skinks. Similar features are also found on the ventral subdigital and distal caudal skin of chameleons. These have only recently been described in any detail, and structurally and functionally are much less well understood than are the setae of geckos and anoles. The seta-like structures of chameleons are not branched (a characteristic of many geckos), nor do they terminate in spatulate tips (which is characteristic of geckos, anoles and skinks). They are densely packed and have attenuated blunt, globose tips or broad, blade-like shafts that are flattened for much of their length. Using a force transducer, we tested the hypothesis that these structures enhance friction and demonstrate that the pilose skin has a greater frictional coefficient than does the smooth skin of these animals. Our results are consistent with friction being generated as a result of side contact of the integumentary filaments. We discuss the evolutionary and functional implications of these seta-like structures in comparison with those typical of other lizard groups and with the properties of seta-mimicking synthetic structures.

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