scholarly journals Diversification through sexual selection on gustatorial courtship traits in dwarf spiders

2021 ◽  
Author(s):  
Shou-Wang Lin ◽  
Gabriele Uhl ◽  
Lara Lopardo
Keyword(s):  
Sexual Selection ◽  
Anterior Part ◽  
Ecological Factors ◽  
Sexually Dimorphic ◽  
Ancestral State ◽  
Evolutionary Patterns ◽  
Character Matrix ◽  
High Lability ◽  
Secretory Glands

Sexual dimorphism can evolve under sexual selection or ecological factors. Sexually dimorphic male prosomal modifications are associated with gustatorial courtship in erigonines. The modifications vary from moderate elevations to bizarre shapes. Males transfer substances from these structures to females, which affect mate acceptance and fecundity. Here, we explore lability of these traits by investigating if modified prosomata are inherently linked to secretory glands, if glands evolved prior to prosomal modifications, and the possibility of convergent evolution and cryptic differentiation, aiming at assessing the possible role of this trait complex in speciation. We reconstructed the positions of glands and the musculature in the anterior part of prosomata of 76 erigonines and three outgroups using micro-CT. We incorporated these characters into an existing morphological character matrix and reanalyzed the phylogeny. Our results support the possession of glands as the ancestral state. The manifold modifications of the prosomal shape have evolved convergently. Differences in glandular positions between species with modified/unmodified prosomata suggest high lability of these traits. Cases of gland loss suggest considerable costs of gustatorial courtship. Our findings demonstrate divergent evolutionary patterns of these traits, and a likely facilitating effect of this type of sexual selection on speciation.

scholarly journals Diversification Through Gustatorial-Courtship: An X-ray Micro-Computed Tomography Study on Dwarf Spiders

2021 ◽  
Author(s):  
Shou-Wang Lin ◽  
Lara Lopardo ◽  
Gabriele Uhl
Keyword(s):  
Computed Tomography ◽  
Sexual Selection ◽  
Anterior Part ◽  
Sexually Dimorphic ◽  
Ancestral State ◽  
Glandular Tissue ◽  
Micro Computed Tomography ◽  
Evolutionary Patterns ◽  
X Ray ◽  
Outgroup Species

Abstract BackgroundSexual selection has been considered to promote diversification and speciation. Sexually dimorphic species have been used to explore the supposed effect, however, with mixed results. In dwarf spiders (Erigoninae), many species are sexually dimorphic - males possess marked prosomal modifications. These male traits vary from moderate elevation to bizarre shapes in various prosomal regions. Previous studies established that male dwarf spiders produce substances in these prosomal modifications that are taken up by the female. Since the transfer of substances increases mating probability of males and oviposition rate in females, the dimorphic traits evolved in the context of sexual selection. Here, we explore the evolutionary lability of the gustatory trait complex by investigating 1) if erigonine modified prosomata are inherently linked to nuptial-gift-producing glands, 2) if gland evolution preceded that of the modified prosomal shapes and by assessing 3) the probability of convergent evolution and cryptic differentiation - with the aim of assessing the role of this trait complex in species divergence.ResultsWe reconstructed the position and extent of the glandular tissue along with the muscular anatomy in the anterior part of the prosoma of 76 erigonine spiders and three outgroup species using X-ray micro-computed tomography. We incorporated the location of glands and muscles into an existing matrix of somatic and genitalic morphological traits of these taxa and reanalyzed their phylogenetic relationship. Our analysis supports that possession of glandular equipment is the ancestral state. The manifold modifications of the prosomal shape have evolved convergently multiple times. We found differences in glandular position between species with both modified and unmodified prosomata, and reported on seven cases of gland loss. ConclusionsOur findings suggest that the occurrence of gustatory gland in sexually monomorphic ancestors has set the stage for the evolution of diverse dimorphic external modifications in dwarf spiders. Variation among congeners indicates that glandular position is highly susceptible to changes. Multiple incidences of gland loss suggest considerable maintenance costs of glandular tissue and nuptial feeding. Our results demonstrate divergent evolutionary patterns of gustatorial-courtship-related traits, and a likely facilitating effect of this type of sexual selection on speciation

scholarly journals Diversification through gustatory courtship: an X-ray micro-computed tomography study on dwarf spiders

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Shou-Wang Lin ◽  
Lara Lopardo ◽  
Gabriele Uhl
Keyword(s):  
Computed Tomography ◽  
Sexual Selection ◽  
Anterior Part ◽  
Divergent Evolution ◽  
Sexually Dimorphic ◽  
Ancestral State ◽  
Glandular Tissue ◽  
Micro Computed Tomography ◽  
Nuptial Gifts ◽  
X Ray

Abstract Background Sexual selection has been considered to promote diversification and speciation. Sexually dimorphic species have been used to explore the supposed effect, however, with mixed results. In dwarf spiders (Erigoninae), many species are sexually dimorphic—males possess marked prosomal modifications. These male traits vary from moderate elevations to bizarre shapes in various prosomal regions. Previous studies established that male dwarf spiders produce substances in these prosomal modifications that are taken up by the females. These substances can act as nuptial gifts, which increase the mating probability of males and the oviposition rate in females. Therefore, these dimorphic traits have evolved in the context of sexual selection. Here, we explore the evolutionary lability of this gustatory trait complex with the aim of assessing the role of this trait complex in species divergence by investigating (1) if erigonine modified prosomata are inherently linked to nuptial-gift-producing glands, (2) if the evolution of the glands evolution preceded that of the modified prosomal shapes, and by assessing (3) the occurrence of convergent/divergent evolution and cryptic differentiation. Results We reconstructed the position and extent of the glandular tissue along with the muscular anatomy in the anterior part of the prosoma of 76 erigonine spiders and three outgroup species using X-ray micro-computed tomography. In all but one case, modified prosomata are associated with gustatory glands. We incorporated the location of glands and muscles into an existing matrix of somatic and genitalic morphological traits of these taxa and reanalyzed their phylogenetic relationship. Our analysis supports that the possession of glandular equipment is the ancestral state and that the manifold modifications of the prosomal shape have evolved convergently multiple times. We found differences in gland position between species with both modified and unmodified prosomata, and reported on seven cases of gland loss. Conclusions Our findings suggest that the occurrence of gustatory glands in sexually monomorphic ancestors has set the stage for the evolution of diverse dimorphic external modifications in dwarf spiders. Differences among congeners suggest that the gland position is highly susceptible to evolutionary changes. The multiple incidences might reflect costs of glandular tissue maintenance and nuptial feeding. Our results indicate divergent evolutionary patterns of gustatory-courtship-related traits, and thus a likely facilitating effect of sexual selection on speciation.

scholarly journals Are sex-biased genes more dispensable?

2009 ◽  
Vol 5 (3) ◽  
pp. 409-412 ◽  
Author(s):  
Judith E. Mank ◽  
Hans Ellegren
Keyword(s):  
Gene Expression ◽  
Sexual Selection ◽  
Molecular Evolution ◽  
Gene Expression Pattern ◽  
Selective Constraint ◽  
Sexually Dimorphic ◽  
Males And Females ◽  
Natural And Sexual Selection ◽  
Rates Of Molecular Evolution

Many genes show different expression levels in males and females, and these form the basis of sexually dimorphic phenotypes. Sex-biased genes experience accelerated rates of protein evolution, which has been attributed to sexual selection. However, it is possible that the increased rates of molecular evolution, and more importantly the sex-biased gene expression pattern itself, are due to decreased selective constraint. This notion may explain many of the patterns associated with sex-biased gene expression, and changes how we should view the role of natural and sexual selection in relation to these genes.

scholarly journals Sex differences in ocular morphology in Caucasian people: a dubious role of sexual selection in the evolution of sexual dimorphism of the human eye

2020 ◽  
Vol 74 (10) ◽  
Author(s):  
Dariusz P. Danel ◽  
Sławomir Wacewicz ◽  
Karel Kleisner ◽  
Zdzisław Lewandowski ◽  
Mariska E. Kret ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Facial Attractiveness ◽  
Total Surface Area ◽  
Sexually Dimorphic ◽  
Human Eye ◽  
Eye Morphology ◽  
Caucasian Men

Abstract The horizontal size of the exposed depigmented sclera in Caucasians has been previously suggested to be sexually dimorphic, and the significance of this phenomenon remains unclear. Here we build on a previous study and extend it by (i) examining sex differences in other measures of ocular morphology and (ii) exploring the link between eye morphology and biometric markers of facial attractiveness. We used facial photographs of 100 Caucasians (50 men) from Eastern-Central Europe and digitally measured four ocular features. Eye measurements were tested for sex differences and associations with morphometric data on facial averageness and sexual shape dimorphism. We found that sclera surface is more horizontally exposed in men, even though the total surface area is similar in both sexes. We also found that eye fissures are rounder (less rectangular) in women than in men and that irises are brighter in women. We did not find any relationship between the examined eye features and two aspects of facial attractiveness: facial averageness and sexual dimorphism in facial shape. Despite being sexually dimorphic, eye features may be loosely linked with the development of facial sexual ornamentation. The role of sexual selection in the evolution of the observed phenomena is disputable. Significance statement It is often argued that because of their physical appearance, human eyes are crucial to interpersonal and social interactions. In many aspects, however, the significance of the human eye architecture is unclear. In this study, we examine sex differences in eye morphology and explore the link between ocular features and biometric measures of facial attractiveness in Caucasian men and women. We found that despite being sexually dimorphic, eye features may be loosely linked with biometric markers of facial attractiveness. We argue that the role of sexual selection in the evolution of the observed sex differences is disputable.

scholarly journals Group size and aquatic vegetation modulates male preferences for female shoals in wild zebrafish, Danio rerio

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aditya Ghoshal ◽  
Anuradha Bhat
Keyword(s):  
Group Size ◽  
Aquatic Vegetation ◽  
Natural Habitat ◽  
Ecological Factors ◽  
Choice Test ◽  
Female Group ◽  
Aquatic Flora ◽  
In The Wild ◽  
The Individual

AbstractShoaling decisions in the wild are determined by a combination of innate preferences of the individual along with the interplay of multiple ecological factors. In their natural habitat as well as in the laboratory, zebrafish is a shoaling fish. Here, we investigate the role of group size and associated vegetation in shaping shoaling preferences of wild male zebrafish. We studied the association preference of males to groups of female shoals in a multi-choice test design. We found that males made greater proportion of visits to an 8-female group compared to 2 and 4-female groups. However, males spent similar proportions of time across the three female-containing groups. When artificial vegetation was incorporated along with female number as an additional factor, we found that males prefer high and moderately vegetated patches compared to low or no-vegetation groups, irrespective of the number of females in these patches. Based on experiments using a novel multi-choice design, our results show that preference for group size can change due to interaction of two separate factors. This work is a first attempt to understand the role of aquatic flora in determining shoaling preferences in zebrafish, using an experimental paradigm consisting of a gradation in female and vegetation densities.

scholarly journals The Role of Sonic Hedgehog-Gli2 Pathway in the Masculinization of External Genitalia

Endocrinology ◽  
2011 ◽  
Vol 152 (7) ◽  
pp. 2894-2903 ◽  
Author(s):  
Shinichi Miyagawa ◽  
Daisuke Matsumaru ◽  
Aki Murashima ◽  
Akiko Omori ◽  
Yoshihiko Satoh ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Sonic Hedgehog ◽  
Hedgehog Signaling ◽  
External Genitalia ◽  
Sexually Dimorphic ◽  
Hedgehog Signaling Pathway ◽  
Initial Development ◽  
Urethral Plate ◽  
Male External Genitalia

During embryogenesis, sexually dimorphic organogenesis is achieved by hormones produced in the gonad. The external genitalia develop from a single primordium, the genital tubercle, and their masculinization processes depend on the androgen signaling. In addition to such hormonal signaling, the involvement of nongonadal and locally produced masculinization factors has been unclear. To elucidate the mechanisms of the sexually dimorphic development of the external genitalia, series of conditional mutant mouse analyses were performed using several mutant alleles, particularly focusing on the role of hedgehog signaling pathway in this manuscript. We demonstrate that hedgehog pathway is indispensable for the establishment of male external genitalia characteristics. Sonic hedgehog is expressed in the urethral plate epithelium, and its signal is mediated through glioblastoma 2 (Gli2) in the mesenchyme. The expression level of the sexually dimorphic genes is decreased in the glioblastoma 2 mutant embryos, suggesting that hedgehog signal is likely to facilitate the masculinization processes by affecting the androgen responsiveness. In addition, a conditional mutation of Sonic hedgehog at the sexual differentiation stage leads to abnormal male external genitalia development. The current study identified hedgehog signaling pathway as a key factor not only for initial development but also for sexually dimorphic development of the external genitalia in coordination with androgen signaling.

Carotenoid-based plumage colouration in red bishops (Euplectes orix) — signalling presence rather than quality?

Behaviour ◽  
2011 ◽  
Vol 148 (11-13) ◽  
pp. 1372-1392 ◽  
Author(s):  
Alice U. Edler ◽  
Thomas W.P. Friedl
Keyword(s):  
Reproductive Success ◽  
Parasite Load ◽  
Blood Parasite ◽  
Male Reproductive Success ◽  
Sexually Dimorphic ◽  
Male Quality ◽  
Plumage Colouration ◽  
Selection For ◽  
Breeding Plumage

AbstractThe role of bright plumage colouration for female choice has been the focus of research in sexual selection for many years, with several studies showing that females prefer the most elaborately ornamented males, which are often also the highest quality individuals. Here, we analysed the associations between reproductive performance and plumage, body condition and blood parasite load in the red bishop (Euplectes orix), a sexually dimorphic and polygynous weaverbird species, where males in a carotenoid-based orange-to-red breeding plumage defend territories and build many nests to which they try to attract females. Male reproductive success in terms of number of nests accepted was mainly determined by the number of nests built, but was also positively related to blood parasite load, while we found no influence of plumage characteristics. Together with previously obtained data, our results indicate that plumage characteristics in the red bishop do not affect male reproductive success and are generally not suitable to reliably indicate male quality. We suggest that the primary function of the brilliant orange-scarlet breeding plumage might be presence signalling in terms of increasing conspicuousness of breeding males to females searching for mates.

Male-male competition, ornamentation and the role of testosterone in sexual selection in red jungle fowl

1990 ◽  
Vol 40 (2) ◽  
pp. 367-373 ◽  
Author(s):  
J. David Ligon ◽  
Randy Thornhill ◽  
Marlene Zuk ◽  
Kristine Johnson
Keyword(s):  
Sexual Selection ◽  
Male Competition ◽  
Red Jungle Fowl
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