Larger Ornaments Research Articles

Is biased mutation sufficient to save runaway sexual selection?

In the 1980s, groundbreaking theoretical studies showed that ornaments displayed during courtship can coevolve with preferences for such ornaments, leading to extreme exaggeration of both traits. Later models cast doubt on such "runaway" sexual selection, showing that even a small cost of preferences can prevent exaggerated ornaments from persisting long-term. It was subsequently shown that if mutations acting on the ornament are biased-tending to produce smaller rather than larger ornaments-then exaggeration can persist even in the presence of preference costs, seemingly vindicating the original models. Here, we unpack an implicit assumption of these "biased mutation" models: Mutations are assumed to lead, on average, to both smaller and less costly ornaments. Biased mutation consequently generates both a fitness cost (due to reduced mating success) and a fitness benefit (due to increased survival). We lift this assumption by separating an individual's investment in an ornament from their efficiency in converting such investment into ornament size. We assume that biased mutation acts only on efficiency but not on investment, and discuss the plausibility of this alternative assumption. Our model predicts that exaggerated ornaments and preferences can persist stably once they arise, but that strong initial preferences are needed to kick-start the runaway process. Consequently, biased mutation alone may not always be sufficient to save runaway sexual selection.

Effect of light bias on male mating signal and female mate choice in a sexually dimorphic Amazon fish

Colourful signals are usually honest indicators of mate quality since they are energetically costly. However, how colours are perceived by choosers is highly affected by the environmental light condition. Amazon black waters are strongly red-biased while clear waters show no apparent colour bias. The sailfin tetra Crenuchus spilurus is a sexually dimorphic Amazon fish species; males have hyperallometric dorsal and anal fins conspicuously ornamented with red and yellow markings. The species has two main lineages, which inhabit black and clear waters. A comparison of the red colouration of the ornaments of males from different lineages indicates that red bias increases the perceived intensity of red colouration but decreases the perceived among-individual variation in red colour. In mate choice experiments, females from all lineages preferred males with larger ornaments. Clear water lineage females were more likely to accept males under red-biased lighting, which increases the apparent red colouration, suggesting the importance of the red colouration in their mate choice. On the other hand, male acceptance by females from black waters did not change under different light conditions, suggesting that signals other than the red colouration (e.g. size of ornaments) were more important in their mate choice.

Is There a Poem That Never Reaches Words, and: And Sends Us, Winged by an Unconscious Will by Rob Baxter

Is There a Poem That Never Reaches Words, and: And Sends Us, Winged by an Unconscious Will by Rob Baxter Rob Baxter Is There a Poem That Never Reaches Words And does the bee, new-come in sterilerepetition, swarm in inconstancy nownever enough to change a universal causeor alter a seraph’s thoughts of universalplace? And how does Du Puy proceed foreverlocked in bronze, a large ornament forflowers heralding seasonal change withoutchange which relegates the General to scrapand rust? A park bench seat is not theatre enoughto evade the artificial, to mediate the willto change, to present difficulty differentlythan undeniable force that transforms,moves, encounters and captures our ownharmony, breath, essence and air. [End Page 235] And Sends Us, Winged by an Unconscious Will How does one cultivate an ignorant eye,An eye trained not to see or reflect?What is the strength of a fictive beingNot divine or man but there to resetBelief, perception and what we come toBehold? The sun in its idea, clean, boldLaunched in heaven without mind or invention,Conceived as unconceivable, cleansed in fireLarge, unnamed, an idea to inspireCelestial awe to complete the myth,Formed in the earth before our breath,Leaving our existence to find aloneDays blazoned but never our ownColoring and shading whatever we’re left. [End Page 236] Rob Baxter Philadelphia, Pennsylvania Copyright © 2022 Johns Hopkins University Press

Female preference for super-sized male ornaments and its implications for the evolution of ornament allometry

It has been argued that disproportionately larger ornaments in bigger males—positive allometry—is the outcome of sexual selection operating on the size of condition dependent traits. We reviewed the literature and found a general lack of empirical testing of the assumed link between female preferences for large ornaments and a pattern of positive allometry in male ornamentation. We subsequently conducted a manipulative experiment by leveraging the unusual terrestrial fish, Alticus sp. cf. simplicirrus, on the island of Rarotonga. Males in this species present a prominent head crest to females during courtship, and the size of this head crest in the genus more broadly exhibits the classic pattern of positive allometry. We created realistic male models standardized in body size but differing in head crest size based on the most extreme allometric scaling recorded for the genus. This included a crest size well outside the observed range for the study population (super-sized). The stimuli were presented to free-living females in a manner that mimicked the spatial distribution of courting males. Females directed greater attention to the male stimulus that exhibited the super-sized crest, with little difference in attention direct to other size treatments. These data appear to be the only experimental evidence from the wild of a female preference function that has been implicitly assumed to drive selection that results in the evolution of positive allometry in male ornamentation.

A Review on “Anjan” Hardwickia binata Roxb: Its Phytochemical Studies, Traditional uses and Pharmacological activities

Hardwickia binata commonly known as “Anjan” belonging to the family Caesalpiniaceae is a handsome medium or large deciduous ornament tree with graceful drooping branch lets is represented by a single species Hardwickia binata Roxb. It is used in folklore medicines for various ailments including diarrhea, leprosy, worm’s infection, indigestion, leucorrhoea, chronic cystitis, gonorrhea, cancer, gram negative and gram positive bacteria and fungi. The parts of plant used as roots, leaves, bark, seed, wood, Husk. The review describes therapeutic efficacy of the leaves, seed, root, husk and its extracts and isolated compounds in different aliments such as antimicrobial, analgesic, antifungal, antibacterial, cardio protective, anti-inflammatory, antitumor and DNA polymerase β inhibition properties of Hardwickia binata were reported. A preliminary Phytochemical screening show that it comprises mainly phenolic compound, saponins, flavonoids, glycosides and tannins, carbohydrate, protein, amino acids, steroids, lipids, quinones, volatile oil, fats and fixed oil. Bioactivity-guided fractionation of an active methyl ethyl ketone extract of Hardwickia binata reported to the isolation of a potent inhibitor, named as Harbinaticacid, a novel diterpenoid and its potency as DNA polymerase β inhibitor. Root bark exudates has been traditionally used to cure breast cancer by Malayali tribes of Chitteri hills. The ethanolic leaf extracts of Hardwickia binata Roxb (Caesalpinaceae) showed a broad-spectrum of activity against both gram-positive and gram-negative bacteria and were screened for antibacterial activity. This systematic review aims to provide information regarding distribution, Morphology, Phytochemical Constituents, Traditional uses and also describes various pharmacological activities reported on the plant Hardwickia binata which may help in future research to improve human health care.

A negative association between horn length and survival in a weakly dimorphic ungulate.

While all models of sexual selection assume that the development and expression of enlarged secondary sexual traits are costly, males with larger ornaments or weapons generally show greater survival or longevity. These studies have mostly been performed in species with high sexual size dimorphism, subject to intense sexual selection. Here, we examined the relationships between horn growth and several survival metrics in the weakly dimorphic Pyrenean chamois (Rupicapra pyrenaica). In this unhunted population living at high density, males and females were able to grow long horns without any apparent costs in terms of longevity. However, we found a negative relationship between horn growth and survival during prime age in males. This association reduces the potential evolutionary consequences of trophy hunting in male chamois. We also found that females with long horns tended to have lower survival at old ages. Our results illustrate the contrasting conclusions that may be drawn when different survival metrics are used in analyses. The ability to detect trade‐off between the expression of male secondary sexual traits and survival may depend more on environmental conditions experienced by the population than on the strength of sexual selection.

НАДМОГИЛЬНЫЕ ПАМЯТНИКИ ДЕТСКИХ ПОГРЕБЕНИЙ XIV–XV ВВ. ИЗ С. КУБАЧИ: ОСОБЕННОСТИ ДЕКОРАТИВНОЙ ОТДЕЛКИ

В статье публикуются надмогильные памятники XIV–XV вв. детских погребений, выявленные автором в 80-е годы ХХ в. на средневековых мусульманских кладбищах «Бидахъ хуппе» (могилы на той стороне) и «Цицила». Кладбища эти расположены примерно в 1,5–2 км южнее старой части с. Кубачи, на нижнем участке горного склона Цицила, обращенного северной стороной к этому селению. Сравнительно небольшое количество резных надгробий XIV–XV вв. этих кладбищ изучены автором и другими исследователями. Не изученными остаются еще немало декоративно отделанных памятников, в том числе стелы, поставленные на могилы детских погребений. В данной статье стелы эти рассматриваются в сравнительном плане с синхронными декорированными надгробиями погребений взрослых или старых людей, выясняются особенности их декоративной отделки. Отмечается, что на могилы детских погребений ставились у изголовья небольшого размера стелы, отделанные растительным орнаментом. Рельефные арабские надписи, выполненные монументальным почерком «цветущий куфи» и на фоне растительного орнамента на надгробиях детских погребений не встречены. Это одно из значительных отличий, помимо размеров, стел детских погребений от декора памятников захоронений взрослых или старых людей. Причиной этого было, вероятно, то, что на надмогильные плиты небольшого размера невозможно было разместить общепринятые для больших плит погребений взрослых или старых мужчин или женщин эпитафии – шахада «Нет божества кроме Аллаха, Мухаммед его посланник», изречения «Смерть – чаша, каждый пьет из нее, могила – ворота, каждый входит в нее» и т.д., выполненные крупными рельефными буквами. По своим формам надгробия детских погребений аналогичны надгробиям погребений взрослых или старых людей сельской общины. Из десяти описанных памятников из сел. Кубачи на четырех имеются собственные имена погребенных.

Choosy Gulf pipefish males ignore age but prefer active females with deeply keeled bodies

Within Syngnathidae (pipefish, seadragons and seahorses), male pregnancy often results in choosy males and competitive females. Females in these species often evolve secondary sexual traits and engage in courtship displays that make their ornaments more noticeable to males. Most syngnathids probably continue to grow larger throughout their lives, but we know little about the relationship between age and mating competition in these taxa. Here, we use the Gulf pipefish, Syngnathus scovelli, to investigate the roles of ornament size, courtship activity level, age and fecundity in female mating competition. We conducted male choice trials that allowed males to choose between similarly sized females of different ages. We also measured age and size at maturity. We found that females with larger ornaments were deeper bodied and engaged in longer courtship displays, yet males chose females based on body depth and display rather than ornamentation. This result suggests that ornamentation serves to help males assess female quality. Female age plays no role in male choice or in female ornamentation. Our finding that males care more about female phenotype than female age considerably simplifies the interpretation of mating patterns in natural populations of Gulf pipefish, which are characterized by considerable age structure.

ABOUT ONE TYPE OF JEWELRY OF THE HEAD OF THE SLAVS: ON THE MATERIALS OF MALYI RZHAVETS AND MARTYNIVKA TREASURES

The article analyses «bobo-similar» plates jewelry from Malyi Rzhavets and Martynivka — four specimens. In 1889 near the village Malyi Rzhavets was found a small treasure of women’s jewelry. In 1907, in the village Martynivka was found another treasure that included the women’s and men’s jewelry and Byzantine wares. Both complexes belong to the treasure of «Martynivka» type or the first chronological hoard-group by O. A. Shcheglova. One can assume the interpretation of these products as large temple ornament or decoration of scythe. Quite similar (though not entirely similar) bronze ware — lamellar temporal rings — are known in the antiquities of Roman times in Central Lithuania. The chronology of these jewelry — the phase B2 or B2 / C1 — 100—230 АD. Finds from Central Lithuania and treasures from Malyi Rzhavets and Martynivka differ in some design features, ornamental motifs and sizes. This can explain the chronological difference.

Female ornamentation and the fecundity trade-off in a sex-role reversed pipefish.

Sexual ornaments found only in females are a rare occurrence in nature. One explanation for this is that female ornaments are costly to produce and maintain and, therefore, females must trade‐off resources related to reproduction to promote ornament expression. Here, we investigate whether a trade‐off exists between female ornamentation and fecundity in the sex‐role reversed, wide‐bodied pipefish, Stigmatopora nigra. We measured two components of the disk‐shaped, ventral‐striped female ornament, body width, and stripe thickness. After controlling for the influence of body size, we found no evidence of a cost of belly width or stripe thickness on female fecundity. Rather, females that have larger ornaments have higher fecundity and thus accurately advertise their reproductive value to males without incurring a cost to fecundity. We also investigated the relationship between female body size and egg size and found that larger females suffer a slight decrease in egg size and fecundity, although this decrease was independent of female ornamentation. More broadly, considered in light of similar findings in other taxa, lack of an apparent fecundity cost of ornamentation in female pipefish underscores the need to revisit theoretical assumptions concerning the evolution of female ornamentation.

Ornaments as socially valuable objects: Jewelry and identity in the Chaco and post-Chaco worlds

This paper explores the relationship between identity and demographic reorganization through an examination of the extent to which Chacoan identity and practice, as demonstrated by the social values attributed to ornaments at Pueblo Bonito during the cultural florescence at Chaco Canyon (A.D. 900–1130), were maintained or transformed by the post-Chaco period inhabitants of Aztec’s West Ruin (A.D. 1140–1290s). The study includes the analysis of the large ornament assemblages from both of these sites, with an emphasis on identifying socially significant dimensions of physical variation through a contextual approach. Utilizing the concepts of value gradations, inalienability, and structured deposition, both similarities and differences in the social use and potential meaning of ornaments at the two sites are identified. Based on similarities in the attributes of ornaments associated with structured ritual deposits and high-status interments, it appears that the residents of Aztec Ruin continued to participate in at least some elements of the Chacoan ritual-ideological complex. I suggest that the depositional practices associated with these socially valuable goods served as citations or references to Chacoan cosmology and the powerful leaders and/or ancestors connected to Pueblo Bonito. Local leaders at Aztec Ruin may have used these references to legitimize their authority by affirming real or reconstructed historical links to Chaco Canyon.

Female collared flycatchers choose neighbouring and older extra‐pair partners from the pool of males around their nests

Extra‐pair copulation is common among passerine birds. Females might engage in this behavior to obtain direct or indirect benefits. They may choose extra‐pair males with larger ornaments, especially if they are costly to produce. Here we studied extra‐pair paternity in the collared flycatcher. Genetic analysis allowed us to identify the presence or absence of extra‐pair young in the focal nests, and to identify extra‐pair fathers. We also identified potential males available as extra‐pair sires around the nests of females who had extra‐pair young. First, we tested the relationship between paternity in own nest and ornament size (wing patch and/or forehead patch), morphological traits and age of social males and females. Second, we compared the same suite of traits among social mates, extra‐pair males and all potential extra‐pair mates. Finally, we investigated the effect of the size of ornaments on the distance between the social nest and that of nest the extra‐pair father. Contrary to our prediction, males with larger ornaments and longer wings lost more paternity in their nests. We also found that early breeders lost less paternity in their nests. Extra‐pair males were older and had longer wings than social and potential extra‐pair males. Females mainly obtained extra‐pair mates near their nests but the distance did not vary according to ornamentation. These results could potentially be explained by differences in mate guarding strategy as older males may be more experienced in guarding their mate and attract other females more easily. More data about mate guarding and prospecting are needed to increase our understanding of mechanisms underlying the extra‐pair paternity in birds.

Algal Turbidity Hampers Ornament Perception, but Not Expression, in a Sex-Role-Reversed Pipefish

Sexual ornaments are used both in intra- and intersexual contexts, and these signals have evolved to function in the particular habitat the animal is adapted to. Habitat characteristics may, however, change rapidly due to anthropogenic effects, sometimes at rates too fast for many organisms to adaptively respond. In aquatic ecosystems, eutrophication is currently changing chemical as well as visual properties of the environment. Algae blooms increase water turbidity, and the reduction of water transparency thus has the potential to alter visual ornaments and their perception. However, results are not congruent. Rather, algae turbidity may decrease, increase, or leave ornaments unaffected. The effect seems to depend on exposure time, condition, population and species. Here, we found that the perception of sexual signals, but not their expression, was hampered by turbidity in the sex-role-reversed pipefish Nerophis ophidion. In a laboratory experiment we found that female sexual ornaments (i.e., blue color markings and a skinfold) and fecundity was unaffected by turbidity. Male adaptive mate choice for larger females with large ornament was, however, hampered under turbid conditions, whereas in clear water males choose larger, more ornamented females. Thus, we show that water turbidity had no effect on signal expression but did hamper ornament perception and consequently randomized mate choice.

The effects of limpet morphology on predation by adult cancrid crabs

Limpets are important prey for some crab species, yet little is known about the role of the limpet shell in defense against crab predation. In an effort to identify limpet shell morphologies that decrease vulnerability to predation by adult cancrid crabs, laboratory feeding trials using three common species of Pacific Northwest limpets (Lottia digitalis, L. pelta and L. scutum) were conducted to assess how different shell morphologies affect mortality and handling time. Large size, shell ornament (radial ridges), and low-spired geometry were expected to result in increased survivorship, and/or longer handling times. Although mortality varied between species, no relationship between size and increased survivorship was observed. Contrary to the expectation that radial ribs resist predation, individuals with smooth morphologies experienced lower mortality. Furthermore, binomial logistic regression indicated that the presence of shell ornament was the only significant explanatory variable in predicting mortality. As species possessing high-spires and ridges may typically occur high in the intertidal where predation risk due to crabs is relatively lower, shell ornament is likely an adaptation to physical factors such as thermal stress, and does not appear to be antipredatory for limpets.

Redescription of Parexus recurvus, an Early Devonian acanthodian from the Midland Valley of Scotland

Parexus Agassiz was one of the first Early Devonian ‘spiny sharks’ to be described. The genus is readily recognized by the large size and ornament of its anterior dorsal fin spine. Although two species were erected, reappraisal of all known specimens indicate they should be synonymized in the type species Parexus recurvus. Farnellia tuberculata Traquair, originally described as a vertebral column, is actually tooth rows of jaw dentition, and is also now considered to be a junior synonym of P. recurvus. Parexus has a perichondrally ossified scapulocoracoid of typical acanthodian shape, and diagnostic features of the family Climatiidae, but has distinctive scales comprising appositional growth zones that closely resemble those of the putative stem chondrichthyan Seretolepis elegans Karatajute-Talimaa.

Negative correlation between male ornament size and female preference intensity in a wild guppy population

Although traditional sexual selection theories for the evolution of ornamental male traits often assume consistency in female preferences for the traits over time, recent theories predict plasticity in female mate preferences and the contribution of plastic female preferences to the maintenance of polymorphism in male sexual ornaments. However, the plasticity of female preferences and its influences on male ornaments are almost unknown in natural populations. Here we examined both the intensity of female preferences and the exaggeration of a male ornament (relative area of orange spots) in a wild population of the guppy (Poecilia reticulata) every few months over a period of 3 years. Results indicated that female preference intensity was negatively correlated with the relative area of orange spots of males. In addition, we found a positive correlation between female preference intensity and the relative area of orange spots of males of their offspring generation. Because the relative area of orange spots of male guppies is a heritable trait, female preferences might have a strong influence on male orange spot size in the next generation. This study provides the first evidence of plastic female preferences depending on the scarcity of males with large ornaments in a natural population. Results of this study imply a possible contribution of female preferences for the maintenance of variation in male ornamentation.

Does female feeding motivation affect the response to a food-mimicking male ornament in the swordtail characin Corynopoma riisei ?

Female response to various aspects of male trait morphology and the effect of female feeding motivation were investigated in the swordtail characin Corynopoma riisei, a species where males are equipped with a flag-like food-mimicking ornament that grows from the operculum. Unfed females responded more strongly to the male ornament and showed a stronger preference for larger ornaments than did fed females. Females were shown not to discriminate between artificial male ornaments of either undamaged or damaged shape.

Is female preference for large sexual ornaments due to a bias to escape predation risk?

BackgroundA female preference for intense sexual visual signals is widespread in animals. Although the preferences for a signal per se and for the intensity of the signal were often regarded to have the identical origin, no study has demonstrated if this is true. It was suggested that the female fiddler crabs prefer males with courtship structures because of direct benefit to escape predation. Here we tested if female preference for both components (i.e. presence and size) of the courtship structure in Uca lactea is from the sensory bias to escape predation. If both components have the identical origin, females should show the same response to different-sized courtship structures regardless of predation risk.ResultsFirst, we observed responses of mate-searching female U. lactea to courting males with full-sized, half-sized and no semidomes which were experimentally manipulated. Females had a directional preference for males with bigger semidomes within normal variation. Thereafter, we tested the effect of predation risk on the female bias in the non-courtship context. When threatened by an avian mock predator, females preferentially approached burrows with full-sized semidomes regardless of reproductive cycles (i.e. reproductive periods and non-reproductive periods). When the predator cue was absent, however, females preferred burrows with semidomes without discriminating structure size during reproductive periods but did not show any bias during non-reproductive periods.ConclusionsResults indicate that selection for the size of courtship structures in U. lactea may have an origin in the function to reduce predation risk, but that the preference for males with structures may have evolved by female choice, independent of predation pressure.

Competitive females are successful females; phenotype, mechanism, and selection in a common songbird

In a variety of taxa, male reproductive success is positively related to expression of costly traits such as large body size, ornaments, armaments, and aggression. These traits are thought to improve male competitive ability, and thus access to limited reproductive resources. Females of many species also express competitive traits. However, we know very little about the consequences of individual variation in competitive traits and the mechanisms that regulate their expression in females. Consequently, it is currently unclear whether females express competitive traits owing to direct selection or as an indirect result of selection on males. Here we examine females of a mildly dimorphic songbird (Junco hyemalis) to determine whether females, show positive covariance in traits (morphology and behavior) that may be important in a competition. We also examine whether trait expression relates either to testosterone (T) in terms of mechanism or to reproductive success in terms of function. We found that larger females were more aggressive and that greater ability to produce T in response to a physiological challenge consisting of a standardized injection of gonadotropin releasing hormone (GnRH) predicted some measures of female body size and aggression. Finally, we found that aggressive females had greater reproductive success. We conclude that testosterone may influence female phenotype and that females may benefit from expressing a competitive phenotype. We also suggest that the mild dimorphism observed in many species may be due in part to direct selection on females rather than simply a correlated response to selection in males.

When mothers make sons sexy: maternal effects contribute to the increased sexual attractiveness of extra-pair offspring

Quality differences between offspring sired by the social and by an extra-pair partner are usually assumed to have a genetic basis, reflecting genetic benefits of female extra-pair mate choice. In the zebra finch (Taeniopygia guttata), we identified a colour ornament that is under sexual selection and appears to have a heritable basis. Hence, by engaging in extra-pair copulations with highly ornamented males, females could, in theory, obtain genes for increased offspring attractiveness. Indeed, sons sired by extra-pair partners had larger ornaments, seemingly supporting the genetic benefit hypothesis. Yet, when comparing ornament size of the social and extra-pair partners, there was no difference. Hence, the observed differences most likely had an environmental basis, mediated, for example, via differential maternal investment of resources into the eggs fertilized by extra-pair and social partners. Such maternal effects may (at least partly) be mediated by egg size, which we found to be associated with mean ornament expression in sons. Our results are consistent with the idea that maternal effects can shape sexual selection by altering the genotype-phenotype relationship for ornamentation. They also caution against automatically attributing greater offspring attractiveness or viability to an extra-pair mate's superior genetic quality, as without controlling for differential maternal investment we may significantly overestimate the role of genetic benefits in the evolution of extra-pair mating behaviour.