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 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 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 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 Heritable variation in colour patterns mediating individual recognition

2017 ◽  
Vol 4 (2) ◽  
pp. 161008 ◽  
Author(s):  
Michael J. Sheehan ◽  
Juanita Choo ◽  
Elizabeth A. Tibbetts
Keyword(s):  
Genetic Diversity ◽  
Balancing Selection ◽  
Phenotypic Diversity ◽  
Individual Recognition ◽  
Genetic Correlations ◽  
Colour Pattern ◽  
Heritable Variation ◽  
Pattern Diversity ◽  
Selection For ◽  
Colour Patterns

Understanding the developmental and evolutionary processes that generate and maintain variation in natural populations remains a major challenge for modern biology. Populations of Polistes fuscatus paper wasps have highly variable colour patterns that mediate individual recognition. Previous experimental and comparative studies have provided evidence that colour pattern diversity is the result of selection for individuals to advertise their identity. Distinctive identity-signalling phenotypes facilitate recognition, which reduces aggression between familiar individuals in P. fuscatus wasps. Selection for identity signals may increase phenotypic diversity via two distinct modes of selection that have different effects on genetic diversity. Directional selection for increased plasticity would greatly increase phenotypic diversity but decrease genetic diversity at associated loci. Alternatively, heritable identity signals under balancing selection would maintain genetic diversity at associated loci. Here, we assess whether there is heritable variation underlying colour pattern diversity used for facial recognition in a wild population of P. fuscatus wasps. We find that colour patterns are heritable and not Mendelian, suggesting that multiple loci are involved. Additionally, patterns of genetic correlations among traits indicated that many of the loci underlying colour pattern variation are unlinked and independently segregating. Our results support a model where the benefits of being recognizable maintain genetic variation at multiple unlinked loci that code for phenotypic diversity used for recognition.

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.

The genetics of warning colour in Peruvian hybrid zones of Heliconius erato and H. melpomene

1989 ◽  
Vol 236 (1283) ◽  
pp. 163-185 ◽  
Keyword(s):  
Genetic Control ◽  
Genetic System ◽  
Colour Pattern ◽  
Stabilizing Selection ◽  
Hybrid Zones ◽  
Warning Signals ◽  
Gradual Evolution ◽  
Selection For ◽  
Colour Patterns ◽  
Ray Patterns

Heliconius warning colour is a good example of a genetic system shaped by strong selection. The genetics of colour patterns in interracial hybrid zones within both H. erato and H. melpomene was investigated. Within each species, the loci controlling these pattern differences are mostly homologous to those known from other races, but have somewhat different phenotypic effects. The precise genetic control varies geographically, even for nearly identical colour patterns. Independent evolution of the same pattern is unlikely; instead evolution of the genetic system is hypothesized to have occurred while stabilizing selection preserved the pattern itself. Single genes often control more than one pattern element. This apparent pleiotropy is in part due to tightly linked loci within 'supergenes': rare recombinants (possibly mutants) in genes controlling 'dennis' and 'ray' patterns were found in both species. However, supergenes, which are likely in polymorphic Batesian mimicry, are not expected to accumulate in Müllerian mimics because polymorphisms, which would favour their evolution, are too transient. The existence of supergenes in Heliconius suggests that major switch genes are gradually built up within a locus rather than evolving wholly by macromutation or by selection for tighter linkage of mimetic genes. This gradual evolution at a single locus might be necessitated by a lack of other sites that can control warning patterns. These genes are strongly epistatic, and heterozygotes and hybrid homozygotes have 'fuzzier' (less sharply defined) and more variable patterns than the pure races. The genetic system controlling colour pattern in Heliconius is clearly canalized and coadapted to produce efficient warning signals.

scholarly journals Maintaining mimicry diversity: optimal warning colour patterns differ among microhabitats in Amazonian clearwing butterflies

2017 ◽  
Vol 284 (1855) ◽  
pp. 20170744 ◽  
Author(s):  
Keith R. Willmott ◽  
Julia C. Robinson Willmott ◽  
Marianne Elias ◽  
Chris D. Jiggins
Keyword(s):  
Bird Species ◽  
Warning Signal ◽  
Colour Pattern ◽  
Butterfly Species ◽  
Insectivorous Birds ◽  
Selection For ◽  
Colour Patterns ◽  
Measured Distribution ◽  
Predator Defence

Mimicry is one of the best-studied examples of adaptation, and recent studies have provided new insights into the role of mimicry in speciation and diversification. Classical Müllerian mimicry theory predicts convergence in warning signal among protected species, yet tropical butterflies are exuberantly diverse in warning colour patterns, even within communities. We tested the hypothesis that microhabitat partitioning in aposematic butterflies and insectivorous birds can lead to selection for different colour patterns in different microhabitats and thus help maintain mimicry diversity. We measured distribution across flight height and topography for 64 species of clearwing butterflies (Ithomiini) and their co-mimics, and 127 species of insectivorous birds, in an Amazon rainforest community. For the majority of bird species, estimated encounter rates were non-random for the two most abundant mimicry rings. Furthermore, most butterfly species in these two mimicry rings displayed the warning colour pattern predicted to be optimal for anti-predator defence in their preferred microhabitats. These conclusions were supported by a field trial using butterfly specimens, which showed significantly different predation rates on colour patterns in two microhabitats. We therefore provide the first direct evidence to support the hypothesis that different mimicry patterns can represent stable, community-level adaptations to differing biotic environments.

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.

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