Does reproductive mode affect sexually-selected coloration? Evaluating UV–blue spots in parthenogenetic and bisexual lizards of the genus Darevskia

Abstract Sexual selection often leads to evolution of conspicuous signals, raising the chances of attracting not only potential mates, but also predators. In lacertid lizards, ultraviolet (UV)–blue spots on flanks and shoulders represent such a trait. Some level of correlation between male and female ornamentation is also known to exist. Therefore, the phenotype of females may change in the absence of sexual selection. We tested this hypothesis on a complex of parthenogenetic and bisexual lizards of the genus Darevskia. We evaluated area, counts, and chromatic properties (UV opponency, saturation) of UV–blue spots and compared the values between the clones and their bisexual progenitor species. We found a fair heterogeneity between the parthenogenetic species, but no general tendency toward higher crypsis or conspicuousness. Values of the parthenogens were not significantly different from the values of sexual females. A possible explanation is that the changes in selective forces associated with parthenogenetic reproduction are too small to affect the resulting pattern of selective pressures on the studied traits, or that the phenotypes of the parthenogens result from the unique combination of parental genomes and are conserved by clonal reproduction.

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Synthesis and Outlook

Male Choice, Female Competition, and Female Ornaments in Sexual Selection ◽

10.1093/oso/9780198818946.003.0009 ◽

2021 ◽

pp. 153-161

Author(s):

Ingo Schlupp

Keyword(s):

Sexual Selection ◽

Mate Choice ◽

Sex Ratios ◽

Empirical Work ◽

Male Mate Choice ◽

Female Ornamentation ◽

Female Quality ◽

Investment In Reproduction ◽

Selection Research ◽

Male Mate

In this final chapter I want to briefly recap what I presented in the previous chapters and provide a few ideas on what might be done in the future to move the field forward. All three factors I discussed as relevant in male mate choice—male investment in reproduction, sex ratios, and variability in partner quality—are still emerging fields in sexual selection research and need more theoretical and empirical work. I suggest that variability in female quality is more important and more complex than currently known. The same is true for sex ratios. On the other hand, I suggest that sheer investment in gametes may be a little less important than currently assumed. Most importantly we need to explore the interactions of these three pathways to male mate choice. Female competition and also female ornamentation are still somewhat enigmatic and both topics are likely to grow in importance for our understanding of sexual selection. I think considering male and female choice together, as well as female and male competition will ultimately provide a more complete picture of Darwinian sexual selection.

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The evolution of bird coloration

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1979.0053 ◽

1979 ◽

Vol 287 (1018) ◽

pp. 63-130 ◽

Cited By ~ 189

Keyword(s):

Sexual Selection ◽

Predation Risk ◽

Multiple Regression ◽

Reproductive Biology ◽

Female Choice ◽

Sex Recognition ◽

Selection Pressures ◽

Advantages And Disadvantages ◽

Selective Pressures ◽

Bird Coloration

The aims in this paper are first to review theories of the evolution of bird coloration and, in some cases, partly revise and extend them, secondly to analyse the coloration of all the birds of a given geographical region using multiple regression, and thirdly on the basis of this analysis to evaluate the various theories. Theories . There have been many discussions of the selective forces acting on the coloration of birds and we review the major proposals in some detail. The earliest suggestion (Darwin 1871) was that the bright coloration of many male birds originated through sexual selection by female choice of the most exotic variants in male plumage. A conflicting view (Hingston 1933) is that brightness has an intimidatory effect on opponents, and that bright male coloration arose through sexual selection but largely due to its advantages against other males in disputes concerning mating access to females. Bird coloration has also been considered in terms of predation (see, for example, Cott 1964 a ). Some birds with bright plumage patterns are known to be unpalatable compared to cryptic species, and certain other patterns have been interpreted as adaptations to confuse predators. Bright colours may commonly be favoured when an individual is anyhow obvious (e.g. through activity) and where it represents an 'unprofitable’ prey for a predator. This interpretation may be particularly relevant to lekking among polygamous males. A special case of unprofitable prey may be ‘perception advertisement’, where an animal signals (by flash patterns or alarm calls) that it has seen a predator (or opponent). It is also possible that bright coloration may serve to deflect predators away from the nest site; this requires in many ways conditions opposite to those for the unprofitable prey solution. Finally, bird colorations can act as a variety of social signals other than threat. Analysis . The coloration of the 516 species of birds that breed and/ or winter in the Western Palaearctic was analysed by multiple regression. Seven regions of a bird’s body plus two areas of flash coloration were recognized and scored for colour on a cryptic/conspicuous scale. Five different age/sex/season categories were recognized and scored separately for each species. These dependent variables were each analysed with respect to 17 independent variables that reflect different aspects of the reproductive biology and ecology of the birds. The advantages and disadvantages of multiple regression as an analytical technique are discussed. Results . The analysis identifies associations between the reproductive biology and ecology of the birds and the coloration of the different regions of the body of the different age/sex/season classes. Apparent exceptions to these associations are also identified and discussed. A relatively large proportion of the associations made sense in terms of the theories presented and usually there was a strong implication that for any specific association one theory was more relevant than any of the others. The results indicate that by far the most potent selective pressures to have shaped bird coloration are those related to predation risk. A number of the theories make use of predation risk, each in a different way, and for most of them some support can be gained for their involvement in the evolution of bird coloration. Of all the theories, however, it is the unprofitable prey model that seems to account for the major part of the variation in bird coloration. By contrast, no clear evidence for the involvement of sexual selection in the evolution of bird coloration could be found. Indeed, many associations, such as that between sexual dimorphism and polygamy, were more readily explicable in terms of selection pressures due to predation risk than of sexual pressures. The suggestion that bird coloration is shaped by predation rather than by sexual selection in no way prevents the coloration, as it evolves, being incorporated within the species and sex recognition system. Conclusions . It is concluded that bird coloration has evolved almost entirely in response to predation-based selective pressures. Although plumage and coloration are involved in species and sex recognition systems, they have not evolved in response to sexual selection pressures. In species that are sexually dimorphic, the male is not brightly coloured as a result of female choice or male: male competition but because he represents a less profitable prey to a predator than the females and juveniles. We predict that brightly coloured birds will most often be found to suffer less from predation than will comparable more cryptic birds (though one of the predation-risk theories does allow the converse to be true).

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Is body shape of mangrove-dwelling monitor lizards (Varanus indicus; Varanidae) sexually dimorphic?

Amphibia-Reptilia ◽

10.1163/017353710x532184 ◽

2011 ◽

Vol 32 (1) ◽

pp. 27-37 ◽

Cited By ~ 12

Author(s):

Jan Hnízdo ◽

Veronika Cikánová ◽

Olga Šimková ◽

Daniel Frynta ◽

Petr Velenský ◽

...

Keyword(s):

Sexual Selection ◽

Body Shape ◽

Sexually Dimorphic ◽

Evolutionary Explanation ◽

Body Measurements ◽

Male And Female ◽

Fecundity Selection ◽

Selective Forces ◽

Monitor Lizards

AbstractIn monitor lizards, males are typically larger than conspecific females, but body shape is usually quite similar in both sexes. This not only represents a puzzle worthy of evolutionary explanation, but also makes field sex determination of monitor lizards difficult. We asked whether subtle differences in body shape follow the same pattern as in other sexually dimorphic lizard taxa and thus can be explained by the same selective forces. We tested the hypotheses that (1) females have a longer abdomen due to fecundity selection and (2) males possess bigger heads due to intrasexual selection. We also hypothesised that (3) male monitors show a wider chests and longer upper fore-limbs to win male-male wrestling matches. We monitored ontogeny in 35 mangrove-dwelling monitors (Varanus indicus). Seventeen body measurements were taken every three months up to the age of 24-34 months. Sex was determined by an ultrasonographic imaging. We employed multiple approaches to remove the effect of size and used both confirmation and exploratory statistics. The results revealed that sexual differences in body shape were small and emerged after maturity. Females have a relatively longer abdomen while males wider chest and longer upper fore-limbs. Thus, the differences in body shape between male and female varanid lizards may be attributed to both fecundity and sexual selection.

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Experimental evidence that female ornamentation increases the acquisition of sperm and signals fecundity

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2006.3757 ◽

2006 ◽

Vol 274 (1609) ◽

pp. 583-590 ◽

Cited By ~ 48

Author(s):

Charlie K Cornwallis ◽

Tim R Birkhead

Keyword(s):

Sexual Selection ◽

Mate Choice ◽

Sexual Partners ◽

Male Mating ◽

Female Ornamentation ◽

Female Ornament ◽

Female Ornaments ◽

Sexual Ornamentation ◽

Gain Access

Mate choice can lead to the evolution of sexual ornamentation. This idea rests on the assumption that individuals with more elaborate ornaments than competitors have higher reproductive success due to gaining greater control over mating decisions and resources provided by partners. Nevertheless, how the resources and quality of sexual partners that individuals gain access to are influenced by the ornamentation of rival individuals remains unclear. By experimentally concealing and subsequently revealing female ornaments to males, we confirm in the fowl, Gallus gallus , that female ornamentation influences male mating decisions. We further show, by manipulating the relative ornament size of females, that when females had larger ornaments than competitors they were more often preferred by males and obtained more sperm, especially from higher quality males, as measured by social status. Males may benefit by investing more sperm in females with larger ornaments as they were in better condition and produced heavier eggs. Female ornament size also decreased during incubation, providing a cue for males to avoid sexually unreceptive females. This study reveals how inter-sexual selection can lead to the evolution of female ornaments and highlights how the reproductive benefits gained from mate choice and bearing ornaments can be dependent upon social context.

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Female ornamentation inMalurusfairy-wrens: a hidden evolutionary gem for understanding female perspectives on social and sexual selection

Emu - Austral Ornithology ◽

10.1071/mu12093 ◽

2013 ◽

Vol 113 (3) ◽

pp. 248-258 ◽

Cited By ~ 20

Author(s):

Jordan Karubian

Keyword(s):

Sexual Selection ◽

Female Ornamentation

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Colour dimorphism in labrid fishes as an adaptation to life on coral reefs

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.0167 ◽

2020 ◽

Vol 287 (1923) ◽

pp. 20200167 ◽

Cited By ~ 1

Author(s):

J. R. Hodge ◽

F. Santini ◽

P. C. Wainwright

Keyword(s):

Sexual Selection ◽

Comparative Analysis ◽

Coral Reefs ◽

Environmental Context ◽

Marine Fishes ◽

Clear Water ◽

Phylogenetic Comparative Analysis ◽

Selective Forces ◽

Colour Dimorphism

Conspicuous coloration displayed by animals that express sexual colour dimorphism is generally explained as an adaptation to sexual selection, yet the interactions and relative effects of selective forces influencing colour dimorphism are largely unknown. Qualitatively, colour dimorphism appears more pronounced in marine fishes that live on coral reefs where traits associated with strong sexual selection are purportedly more common. Using phylogenetic comparative analysis, we show that wrasses and parrotfishes exclusive to coral reefs are the most colour dimorphic, but surprisingly, the effect of habitat is not influenced by traits associated with strong sexual selection. Rather, habitat-specific selective forces, including clear water and structural refuge, promote the evolution of pronounced colour dimorphism that manifests colours less likely to be displayed in other habitats. Our results demonstrate that environmental context ultimately determines the evolution of conspicuous coloration in colour-dimorphic labrid fishes, despite other influential selective forces.

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Evolutionary Origins of Viviparity in the Reptilia. II. Serpentes, Amphisbaenia, and Ichthyosauria

Amphibia-Reptilia ◽

10.1163/156853885x00290 ◽

1985 ◽

Vol 6 (3) ◽

pp. 259-291 ◽

Cited By ~ 107

Author(s):

Daniel G. Blackburn

Keyword(s):

Phylogenetic Relationships ◽

Previous Analysis ◽

Reproductive Mode ◽

Classification Systems ◽

Old World ◽

Selective Pressures ◽

Evolutionary Origins ◽

Published Evidence ◽

Reptile Species ◽

Biogeographic Regions

AbstractSuperimposition of reproductive mode data from the literature over phylogenetic classification systems reveals that viviparity (live-bearing reproduction) has evolved on at least 35 independent occasions among the Serpentes, once in the Amphisbaenia, and once in the Ichthyosauria. Of the ophidian origins of the live-bearing mode, at least fourteen have occurred in the Colubridae, twelve in the Viperidae, three in the Hydrophiidae (used in the sense of Smith et al., 1977), and one in each of the following groups: Boidae, Acrochordidae, Tropidophiidae, Uropeltidae, Typhlopidae, and Elapidae. Previous analysis has distinguished and defined 45 origins of viviparity among the lizards. Here, ten additional saurian origins are recognized on the basis of unpublished and recently published evidence, three in the Iguanidae, two in the Scincidae, and one in each of the following groups: Agamidae, Chamaeleontidae, Anguidae, Xenosauridae, and Anniellidae. As phylogenetic relationships are clarified, further origins seem likely to be detected, particularly in the Colubridae, Hydrophiidae, Scincidae, and Iguanidae. At present, however, at least 92 origins of viviparity can be recognized within the class Reptilia. Reptilian viviparity has arisen on multiple occasions in each of the six major biogeographic regions, with a majority of the origins having occurred in the Old World. Nearly 19% of the extant reptile species are probably live-bearers, including more than 20% of the snakes and over 19% of the lizards. About 71 % of the viviparous species belong to either the Scincidae, Colubridae, Viperidae, or Iguanidae. The discontinuous distribution of the origins of viviparity among the reptilian families supports the hypothesis that selective pressures, preadaptations, and constraints vary at high taxonomic levels.

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Migration and the evolution of sexual dichromatism: evolutionary loss of female coloration with migration among wood-warblers

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.0375 ◽

2015 ◽

Vol 282 (1809) ◽

pp. 20150375 ◽

Cited By ~ 25

Author(s):

Richard K. Simpson ◽

Michele A. Johnson ◽

Troy G. Murphy

Keyword(s):

Sexual Selection ◽

Sexual Dichromatism ◽

Ancestral State ◽

Migration Distance ◽

Female Ornamentation ◽

Wood Warblers ◽

Selection For ◽

Evolution Of Migration ◽

And Migration ◽

Female Coloration

The mechanisms underlying evolutionary changes in sexual dimorphism have long been of interest to biologists. A striking gradient in sexual dichromatism exists among songbirds in North America, including the wood-warblers (Parulidae): males are generally more colourful than females at northern latitudes, while the sexes are similarly ornamented at lower latitudes. We use phylogenetically controlled comparative analysis to test three non-mutually exclusive hypotheses for the evolution of sexual dichromatism among wood-warblers. The first two hypotheses focus on the loss of female coloration with the evolution of migration, either owing to the costs imposed by visual predators during migration, or owing to the relaxation of selection for female social signalling at higher latitudes. The third hypothesis focuses on whether sexual dichromatism evolved owing to changes in male ornamentation as the strength of sexual selection increases with breeding latitude. To test these hypotheses, we compared sexual dichromatism to three variables: the presence of migration, migration distance, and breeding latitude. We found that the presence of migration and migration distance were both positively correlated with sexual dichromatism, but models including breeding latitude alone were not strongly supported. Ancestral state reconstruction supports the hypothesis that the ancestral wood-warblers were monochromatic, with both colourful males and females. Combined, these results are consistent with the hypotheses that the evolution of migration is associated with the relaxation of selection for social signalling among females and that there are increased predatory costs along longer migratory routes for colourful females. These results suggest that loss of female ornamentation can be a driver of sexual dichromatism and that social or natural selection may be a stronger contributor to variation in dichromatism than sexual selection.

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RNA Structure Duplication in the Dengue Virus 3′ UTR: Redundancy or Host Specificity?

mBio ◽

10.1128/mbio.02506-18 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 22

Author(s):

Luana de Borba ◽

Sergio M. Villordo ◽

Franco L. Marsico ◽

Juan M. Carballeda ◽

Claudia V. Filomatori ◽

...

Keyword(s):

Viral Replication ◽

Viral Genome ◽

Untranslated Region ◽

Rna Synthesis ◽

Rna Structures ◽

Functional Diversification ◽

Selective Pressures ◽

Selective Forces ◽

Rna Elements ◽

Selection Of

ABSTRACTFlaviviruses include a diverse group of medically important viruses that cycle between mosquitoes and humans. During this natural process of switching hosts, each species imposes different selective forces on the viral population. Using dengue virus (DENV) as model, we found that paralogous RNA structures originating from duplications in the viral 3′ untranslated region (UTR) are under different selective pressures in the two hosts. These RNA structures, known as dumbbells (DB1 and DB2), were originally proposed to be enhancers of viral replication. Analysis of viruses obtained from infected mosquitoes showed selection of mutations that mapped in DB2. Recombinant viruses carrying the identified variations confirmed that these mutations greatly increase viral replication in mosquito cells, with low or no impact in human cells. Use of viruses lacking each of the DB structures revealed opposite viral phenotypes. While deletion of DB1 reduced viral replication about 10-fold, viruses lacking DB2 displayed a great increase of fitness in mosquitoes, confirming a functional diversification of these similar RNA elements. Mechanistic analysis indicated that DB1 and DB2 differentially modulate viral genome cyclization and RNA replication. We found that a pseudoknot formed within DB2 competes with long-range RNA-RNA interactions that are necessary for minus-strand RNA synthesis. Our results support a model in which a functional diversification of duplicated RNA elements in the viral 3′ UTR is driven by host-specific requirements. This study provides new ideas for understanding molecular aspects of the evolution of RNA viruses that naturally jump between different species.IMPORTANCEFlaviviruses constitute the most relevant group of arthropod-transmitted viruses, including important human pathogens such as the dengue, Zika, yellow fever, and West Nile viruses. The natural alternation of these viruses between vertebrate and invertebrate hosts shapes the viral genome population, which leads to selection of different viral variants with potential implications for epidemiological fitness and pathogenesis. However, the selective forces and mechanisms acting on the viral RNA during host adaptation are still largely unknown. Here, we found that two almost identical tandem RNA structures present at the viral 3′ untranslated region are under different selective pressures in the two hosts. Mechanistic studies indicated that the two RNA elements, known as dumbbells, contain sequences that overlap essential RNA cyclization elements involved in viral RNA synthesis. The data support a model in which the duplicated RNA structures differentially evolved to accommodate distinct functions for viral replication in the two hosts.

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