scholarly journals HIGH-RESOLUTION CHARACTERIZATION OF MALE ORNAMENTATION AND REEVALUATION OF SEX LINKAGE IN GUPPIES

2020 ◽  
Author(s):  
Jake Morris ◽  
Iulia Darolti ◽  
Wouter van der Bijl ◽  
Judith E. Mank
Keyword(s):  
High Resolution ◽  
Natural Populations ◽  
Colour Pattern ◽  
Sexually Dimorphic ◽  
Animal Colouration ◽  
In The Wild ◽  
Colour Changes ◽  
Colour Patterns ◽  
Male Ornaments

AbstractColouration plays a key role in the ecology of many species, influencing how an organism interacts with its environment, other species and conspecifics. Guppies are sexually dimorphic, with males displaying sexually selected colouration resulting from female preference. Previous work has suggested that much of guppy colour pattern variation is Y-linked. However, it remains unclear how many individual colour patterns are Y-linked in natural populations as much of the previous work has focused on phenotypes either not found in the wild, or aggregate measures such as total colour area. Moreover, ornaments have traditionally been identified and delineated by hand, and computational methods now make it possible to extract pixels and identify ornaments more automatedly, reducing the potential for human bias. Here we developed a pipeline for automated ornament identification and high-resolution image analysis of male guppy colour patterns and applied it to a multigenerational pedigree. Our results show that loci controlling the presence or absence of individual male ornaments in our population are not predominantly Y-linked. However, we find that ornaments of similar colour are not independent of each other, and modifier loci that affect whole animal colouration appear to be at least partially Y-linked. Considering these results, Y-linkage of individual ornaments may not be important in driving colour changes in natural populations of guppies, or in expansions of the non-recombining Y region, while Y-linked modifier loci that affect aggregate traits may well play an important role.

scholarly journals High-resolution characterization of male ornamentation and re-evaluation of sex linkage in guppies

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201677
Author(s):  
Jake Morris ◽  
Iulia Darolti ◽  
Wouter van der Bijl ◽  
Judith E. Mank
Keyword(s):  
High Resolution ◽  
Natural Populations ◽  
Colour Pattern ◽  
Sexually Dimorphic ◽  
In The Wild ◽  
Colour Changes ◽  
Colour Patterns ◽  
Male Ornaments ◽  
Automated Methods

Coloration plays a key role in the ecology of many species, influencing how an organism interacts with its environment, other species and conspecifics. Guppies are sexually dimorphic, with males displaying sexually selected coloration resulting from female preference. Previous work has suggested that much of guppy colour pattern variation is Y-linked. However, it remains unclear how many individual colour patterns are Y-linked in natural populations as much of the previous work has focused on phenotypes either not found in the wild, or aggregate measures such as total colour area. Moreover, ornaments have traditionally been identified and delineated by hand, and computational methods now make it possible to extract pixels and identify ornaments with automated methods, reducing the potential for human bias. Here we developed a pipeline for semi-automated ornament identification and high-resolution image analysis of male guppy colour patterns and applied it to a multigenerational pedigree. Our results show that loci controlling the presence or the absence of individual male ornaments in our population are not predominantly Y-linked. However, we find that ornaments of similar colour are not independent of each other, and modifier loci that affect whole animal coloration appear to be at least partially Y-linked. Considering these results, Y-linkage of individual ornaments may not be important in driving colour changes in natural populations of guppies, or in expansions of the non-recombining Y region, while Y-linked modifier loci that affect aggregate traits may well play an important role.

scholarly journals Sexually dimorphic dorsal coloration in a jumping spider: testing a potential case of sex-specific mimicry

2021 ◽  
Vol 8 (6) ◽  
pp. 210308
Author(s):  
Collette Cook ◽  
Erin C. Powell ◽  
Kevin J. McGraw ◽  
Lisa A. Taylor
Keyword(s):  
Colour Pattern ◽  
Sexually Dimorphic ◽  
Sham Control ◽  
Jumping Spider ◽  
Negative Results ◽  
Potential Case ◽  
Opposite Sex ◽  
Colour Patterns ◽  
Hymenopteran Insects ◽  
Predation Rates

To avoid predation, many animals mimic behaviours and/or coloration of dangerous prey. Here we examine potential sex-specific mimicry in the jumping spider Habronattus pyrrithrix . Previous work proposed that males' conspicuous dorsal coloration paired with characteristic leg-waving (i.e. false antennation) imperfectly mimics hymenopteran insects (e.g. wasps and bees), affording protection to males during mate-searching and courtship. By contrast, less active females are cryptic and display less leg-waving. Here we test the hypothesis that sexually dimorphic dorsal colour patterns in H. pyrrithrix are most effective when paired with sex-specific behaviours. We manipulated spider dorsal coloration with makeup to model the opposite sex and exposed them to a larger salticid predator ( Phidippus californicus ). We predicted that males painted like females should suffer higher predation rates than sham-control males. Likewise, females painted like males should suffer higher predation rates than sham-control females. Contrary to expectations, spiders with male-like coloration were attacked more than those with female-like coloration, regardless of their actual sex. Moreover, males were more likely to be captured, and were captured sooner, than females (regardless of colour pattern). With these unexpected negative results, we discuss alternative functional hypotheses for H. pyrrithrix colours, as well as the evolution of defensive coloration generally.

scholarly journals Risk of social colours in an agamid lizard: implications for the evolution of dynamic signals

2019 ◽  
Vol 15 (5) ◽  
pp. 20190207 ◽  
Author(s):  
Madhura S. Amdekar ◽  
Maria Thaker
Keyword(s):  
Natural Selection ◽  
Social Interactions ◽  
Predation Risk ◽  
Colour Pattern ◽  
Male Aggression ◽  
Visual Systems ◽  
In The Wild ◽  
Predation Costs ◽  
Colour Patterns ◽  
Ecological Cost

The forces of sexual and natural selection are typically invoked to explain variation in colour patterns of animals. Although the benefits of conspicuous colours for social signalling are well documented, evidence for their ecological cost, especially for dynamic colours, remains limited. We examined the riskiness of colour patterns of Psammophilus dorsalis , a species in which males express distinct colour combinations during social interactions. We first measured the conspicuousness of these colour patterns on different substrates based on the visual systems of conspecifics and predators (bird, snake, canid) and then quantified actual predation risk on these patterns using wax/polymer lizard models in the wild. The black and red male state exhibited during courtship was the most conspicuous to all visual systems, while the yellow and orange male aggression state and the brown female colour were least conspicuous. Models bearing the courtship colour pattern experienced the highest predator attacks, irrespective of the substrate they were placed on. Thus, social colours of males are not only conspicuous but also risky. Using physiological colours to shift in and out of conspicuous states may be an effective evolutionary solution to balance social signalling benefits with predation costs.

scholarly journals III. Studies in colour changes of fish. - Part II. —An analysis of the colour patterns of the dab. - Part III. —The action of nicotin and adrenalin in the dab. - Part IV. —The action of caffeine in the dab, and a theory of the control of colour changes in fish

1927 ◽  
Vol 215 (421-430) ◽  
pp. 177-200 ◽  
Keyword(s):  
The Body ◽  
Colour Pattern ◽  
Complete Analysis ◽  
Morphological Variations ◽  
Differential Reaction ◽  
Flat Fish ◽  
Colour Changes ◽  
Morphological Differences ◽  
Colour Patterns ◽  
The Many

In the course of investigations on the action of certain drugs on the colour of the dab, it became increasingly evident that not only should a microscopic examination be made of the results, but that apart from a complete analysis of the colour pattern of the fish, such an examination would be unintelligible. I am not aware that any such analysis has been made of so complicated a colour scheme. Abolin (see List of Papers, p. 198) has analysed the colour pattern of the minnow, and in a previous paper I have pointed out that the barring on the minnow is partly due to physiological differences and partly to morphological variations. Sumner has also given a description of the patterns on certain flat-fish, but his observations were purely macroscopic. The main problem which has presented itself in this field is this :—Do all the chromatophores on the skin expand and contract synchronously and to the same degree? In other words: Are the various colour phases and manifestations of markings due to morphological differences alone? Sumner, as the result of researches carried out on flat-fish, has come to the conclusion that the many variations of colour, pattern and shade cannot be altogether explained by the assumption of a synchronous reaction of all the chromatophores, and that there must be some differential reaction of the chromatophores situated on the markings. Hogben is opposed to this view and thinks that, as “the extent of melanophore expansion in response to the intensity of a uniform background displays a very subtle gradation, it is not unlikely that the effect of a variegated background is simply to reproduce throughout the body a state of melanophore response, which renders more or less apparent a pattern dependent wholly on the numerical distribution of the melanophores in different areas.” In the present research this problem has been approached by a study of the reactions of the dab to uniform backgrounds, to ascertain the extent of the “subtle gradation” and to supply the necessary data for the further discussion of this problem.

scholarly journals Towards cancer-aware life-history modelling

2015 ◽  
Vol 370 (1673) ◽  
pp. 20140234 ◽  
Author(s):  
Hanna Kokko ◽  
Michael E. Hochberg
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Cancer Susceptibility ◽  
Natural Populations ◽  
Sexually Dimorphic ◽  
Adaptive Responses ◽  
Extrinsic Mortality ◽  
Size Evolution ◽  
In The Wild

Studies of body size evolution, and life-history theory in general, are conducted without taking into account cancer as a factor that can end an organism's reproductive lifespan. This reflects a tacit assumption that predation, parasitism and starvation are of overriding importance in the wild. We argue here that even if deaths directly attributable to cancer are a rarity in studies of natural populations, it remains incorrect to infer that cancer has not been of importance in shaping observed life histories. We present first steps towards a cancer-aware life-history theory, by quantifying the decrease in the length of the expected reproductively active lifespan that follows from an attempt to grow larger than conspecific competitors. If all else is equal, a larger organism is more likely to develop cancer, but, importantly, many factors are unlikely to be equal. Variations in extrinsic mortality as well as in the pace of life—larger organisms are often near the slow end of the fast–slow life-history continuum—can make realized cancer incidences more equal across species than what would be observed in the absence of adaptive responses to cancer risk (alleviating the so-called Peto's paradox). We also discuss reasons why patterns across species can differ from within-species predictions. Even if natural selection diminishes cancer susceptibility differences between species, within-species differences can remain. In many sexually dimorphic cases, we predict males to be more cancer-prone than females, forming an understudied component of sexual conflict.

scholarly journals FACTORS INFLUENCING THE EFFECT OF SEGREGATION DISTORTION IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 107 (3) ◽  
pp. 375-393
Author(s):  
Rayla Greenberg Temin ◽  
Marta Marthas
Keyword(s):  
Segregation Distortion ◽  
Pericentric Inversion ◽  
Natural Populations ◽  
Special Test ◽  
Recessive Lethal ◽  
Factors Influencing ◽  
Direct Measurements ◽  
Tight Linkage ◽  
In The Wild

ABSTRACT The major components of the SD system have been examined in two natural populations of D. melanogaster to investigate how SD behaves and is maintained in nature and to estimate its impact and efficiency. A twofold approach was used: (1) direct measurements of segregation distortion in wild males and (2) measurement of sensitivity of wild SD  + chromosomes to SD action. Characterization of newly isolated SD chromosomes and of a large number of SD  + chromosomes from nature demonstrated that (1) SD can operate efficiently in the wild genome: 45% of SD/SD  + males collected from nature had k values larger than 0.70. (2) Forty-three of 44 newly recovered SD chromosomes are of the SD-72 type, having a small pericentric inversion that maintains tight linkage among the Sd, E(SD) and Rsp loci in the SD complex. In 1956, most SD chromosomes in Madison lacked this inversion. (3) Only 12 of the 44 SD chromosomes carried a recessive lethal (compared with five of six in 1956), and many of the viable SD chromosomes were fertile as homozygotes, indicating that SD homozygotes need not have obvious reductions in fitness. (4) Among more than 500 wild chromosomes assayed for response to distortion by a strong SD, at least 40-50% were sensitive, about 33% were partially sensitive and 17% were insensitive. This frequency of sensitives is higher than in reports from some other populations. An estimated 12% of the wild chromosomes were classified as true Rspi by their constellation of effects, including a special test of ability to cause self-distortion of a "suicide" chromosome, R(cn)-10. In a direct assay with R(cn)-10, an independent sample of 99 chromosomes from nature gave 30% putative Rspi. Thus, these populations contain in the range of 12-30% Rspi. (5) Chromosomes supersensitive to SD, previously described for certain laboratory stocks, were also found to coexist in nature with SD. (6) Profiles of wild chromosomes with a panel of three or four different SD testers suggest a series of allelic alternatives at the Rsp locus including supersensitive, sensitive, semisensitive and insensitive, and that loci other than Rsp may also be important in determining the effect of SD in nature.

scholarly journals Generalisation behaviour of predators toward warning signals displayed by harmful prey: answers from a videogame played by humans

2018 ◽  
Author(s):  
Mónica Arias ◽  
David Griffiths ◽  
Mathieu Joron ◽  
John Davey ◽  
Simon Martin ◽  
...  
Keyword(s):  
Video Game ◽  
Natural Populations ◽  
Computer Game ◽  
Warning Signals ◽  
Natural Systems ◽  
Natural Predator ◽  
In The Wild ◽  
Human Predation ◽  
Colour Patterns ◽  
Set Up

AbstractThe persistence of several warning signals in sympatry is a puzzling evolutionary question because selection favours convergence of colour patterns among toxic species. Such convergence is shaped by predators’ reaction to similar but not identical stimulus, i.e. generalisation behaviour. However, studying generalisation behaviour in complex natural communities of predators is challenging, and is thus generally limited to simple variations of prey colour patterns. Here, we used humans as surrogate predators to investigate generalisation behaviours on two prey communities with different level of warning signals complexity. Humans’ generalisation capacities were estimated using a computer game simulating a simple (4 morphs) and a complex (10 morphs) community of defended (associated with a penalty) and palatable butterflies. Colour patterns used in the game are actually observed in natural populations of the defended butterflies H. numata, and generalisation behaviour of natural predator’s communities on these colour patterns have previously been investigated in the wild, allowing direct comparison with human behaviour. We investigated human predation behaviour by recording attack rates on the different defended and palatable colour patterns, as well as player survival time (i.e. score). Phenotypic similarity among the different colour patterns was precisely quantified using a custom algorithm accounting for both colour and pattern variations (CPM method). By analysing attack behaviours of 491 game players, we found that learning was more efficient in the simple prey community. Additionally, profitable prey gained protection from sharing key visual features with unprofitable prey in both communities while learning, in accordance with natural predator behaviours. Moreover, other behaviours observed in natural predators, such as colour neophobia, were detected in humans and shaped morph vulnerability during the game. Similarities between our results in humans and the reaction of natural predator communities to the same colour patterns validate our video-game as a useful proxy to study predator behaviour. This experimental set-up can thus be compared to natural systems, enabling further investigations of generalisation on mimicry evolution.

scholarly journals Variable coloration is associated with dampened population fluctuations in noctuid moths

2015 ◽  
Vol 282 (1808) ◽  
pp. 20142922 ◽  
Author(s):  
Anders Forsman ◽  
Per-Eric Betzholtz ◽  
Markus Franzén
Keyword(s):  
Individual Variation ◽  
Time Series Data ◽  
Biotic Interactions ◽  
Colour Pattern ◽  
Series Data ◽  
Population Fluctuations ◽  
Population Abundance ◽  
In The Wild ◽  
Colour Patterns ◽  
Abundance Fluctuations

Theory and recent reviews state that greater genetic and phenotypic variation should be beneficial for population abundance and stability. Experimental evaluations of this prediction are rare, of short duration and conducted under controlled environmental settings. The question whether greater diversity in functionally important traits stabilizes populations under more complex ecological conditions in the wild has not been systematically evaluated. Moths are mainly nocturnal, with a large variation in colour patterns among species, and constitute an important food source for many types of organisms. Here, we report the results of a long-term (2003–2013) monitoring study of 115 100 noctuid moths from 246 species. Analysis of time-series data provide rare evidence that species with higher levels of inter-individual variation in colour pattern have higher average abundances and undergo smaller between-year fluctuations compared with species having less variable colour patterns. The signature of interspecific temporal synchronization of abundance fluctuations was weak, suggesting that the dynamics were driven by species-specific biotic interactions rather than by some common, density-independent factor(s). We conclude that individual variation in colour patterns dampens population abundance fluctuations, and suggest that this may partly reflect that colour pattern polymorphism provides protection from visually oriented predators and parasitoids.

scholarly journals Uncovering the effects of Müllerian mimicry on the evolution of conspicuousness in colour patterns

2019 ◽  
Author(s):  
Ombeline Sculfort ◽  
Ludovic Maisonneuve ◽  
Marianne Elias ◽  
Thomas G. Aubier ◽  
Violaine Llaurens
Keyword(s):  
Predation Risk ◽  
Prey Species ◽  
Colour Pattern ◽  
Warning Coloration ◽  
Local Composition ◽  
Müllerian Mimicry ◽  
In The Wild ◽  
Mullerian Mimicry ◽  
Colour Patterns ◽  
Number Of Individuals

AbstractThe conspicuousness of colour pattern in defended species associates with a high detectability by predators, making its evolution puzzling. Müllerian mimicry, the convergence of warning coloration among defended prey species, is pervasive in communities of conspicuous prey, and mimicry switches, with mutant individuals having the same colour pattern as other co-mimetic species, may often associate with changes in conspicuousness. Yet, the implication of mimicry for the evolution of conspicuousness has not been considered. Here, we build a model describing the population dynamics of conspicuous defended prey to explore the invasion conditions of mutants that differ from other individuals by their conspicuousness. We assume that predation risk depends not only on the number of individuals sharing a given colour pattern within the population but also on the presence of co-mimetic species. We compare the evolutionary fates of mutant colour patterns (1) that are similar to the ancestral colour pattern and thus belong to the same mimicry ring (assemblage of co-mimetic species), or (2) that are different from the ancestral colour pattern and thus potentially belong to a distinct mimicry ring. Our analytical derivations show that (1) less conspicuous colour patterns are more likely to be selected within mimicry ring, and that (2) a mimicry switch lowering predation risk can promote the invasion of a more conspicuous colour pattern. We thus highlight that the variation in conspicuousness observed in the wild results not only from the characteristics of the colour pattern (detectability, salience) but also from the local composition of mimetic communities.

scholarly journals The genomic basis of colour pattern polymorphism in the harlequin ladybird

2018 ◽  
Author(s):  
Mathieu Gautier ◽  
Junichi Yamaguchi ◽  
Julien Foucaud ◽  
Anne Loiseau ◽  
Aurélien Ausset ◽  
...  
Keyword(s):  
Phenotypic Variation ◽  
Population Genomics ◽  
Allelic Variation ◽  
Natural Populations ◽  
Colour Pattern ◽  
Harlequin Ladybird ◽  
Distinct Colour ◽  
Pattern Polymorphism ◽  
Colour Patterns ◽  
Genomic Basis

Many animal species are comprised of discrete phenotypic forms. Understanding the genetic mechanisms generating and maintaining such phenotypic variation within species is essential to comprehending morphological diversity. A common and conspicuous example of discrete phenotypic variation in natural populations of insects is the occurrence of different colour patterns, which has motivated a rich body of ecological and genetic research1–6. The occurrence of dark, i.e. melanic, forms, displaying discrete colour patterns, is found across multiple taxa, but the underlying genomic basis remains poorly characterized. In numerous ladybird species (Coccinellidae), the spatial arrangement of black and orange patches on adult elytra varies wildly within species, forming strikingly different complex colour patterns7,8. In the harlequin ladybird Harmonia axyridis, more than 200 distinct colour forms have been described, which classic genetic studies suggest result from allelic variation at a single, unknown, locus9,10. Here, we combined whole-genome sequencing, population genomics, gene expression and functional analyses, to establish that the gene pannier controls melanic pattern polymorphism in H. axyridis. We show that pannier, which encodes an evolutionary conserved transcription factor, is necessary for the formation of melanic elements on the elytra. Allelic variation in pannier leads to protein expression in distinct domains on the elytra, and thus determines the distinct colour patterns in H. axyridis. Recombination between pannier alleles may be reduced by a highly divergent sequence of ca. 170 kb in the cis-regulatory regions of pannier with a 50 kb inversion between colour forms. This likely helps maintaining the distinct alleles found in natural populations. Thus we propose that highly variable discrete colour forms can arise in natural populations through cis-regulatory allelic variation of a single gene.

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