Broad-sense sexual selection, sex gene pool evolution, and speciation

Genome ◽  
1999 ◽  
Vol 42 (6) ◽  
pp. 1033-1041 ◽  
Author(s):  
A Civetta ◽  
R S Singh
Keyword(s):  
Sexual Selection ◽  
Potential Role ◽  
Selection Process ◽  
Broad Sense ◽  
Good Genes ◽  
Secondary Sexual Traits ◽  
Male Characters ◽  
Sexual Conflicts ◽  
Sexual Traits

Studies of sexual selection have traditionally focused on explaining the extreme sexual dimorphism in male secondary sexual traits and elaborate mating behaviors displayed by males during courtship. In recent years, two aspects of sexual selection have received considerable attention in the literature: an extension of the sexual selection concept to other traits (i.e., postcopulatory behaviors, external and internal genital morphology, gametes, molecules), and alternative mechanistic explanations of the sexual selection process (i.e., coevolutionary runaway, good-genes, sexual conflicts). This article focuses on the need for an extension of sexual selection as a mechanism of change for courtship and (or) mating male characters (i.e., narrow-sense sexual selection) to all components of sexuality not necessarily related to courtship or mating (i.e., broad-sense sexual selection). We bring together evidence from a wide variety of organisms to show that sex-related genes evolve at a fast rate, and discuss the potential role of broad-sense sexual selection as an alternative to models that limit speciation to strict demographic conditions or treat it simply as an epiphenomenon of adaptive evolution.Key words: sexual selection, sex-related genes, speciation.

scholarly journals Allometry, sexual selection, and evolutionary lines of least resistance shaped the evolution of exaggerated sexual traits within the genus Tyrannus

2021 ◽  
Author(s):  
Martin N Fasanelli ◽  
Pablo S Milla Carmona ◽  
Ignacio M Soto ◽  
Diego T Tuero
Keyword(s):  
Sexual Selection ◽  
Selection Process ◽  
Functional Limitations ◽  
Biological Evolution ◽  
Interspecific Variation ◽  
Shape Variation ◽  
Secondary Sexual Traits ◽  
The Face ◽  
Repeated Evolution ◽  
Sexual Traits

Variational properties hold a fundamental role in shaping biological evolution, exerting control over the magnitude and direction of evolutionary change elicited by microevolutionary processes that sort variation, such as selection or drift. We studied the Tyrannus genus, as a model for examining the conditions and drivers that facilitate the repeated evolution of exaggerated, secondary sexual traits in the face of significant functional limitations. We study the role of allometry, sexual selection, and their interaction on the diversification of tail morphology in the genus, assessing whether and how they promoted or constrained phenotypic evolution. The exaggerated and functionally-constrained long feathers of deep-forked species, T. savana and T. forficatus, independently diverged from the rest of the genus following the same direction of main interspecific variation common to the entire cluster of species. However, at a macroevolutionary scale those axes summarising both sexual dimorphism and allometric variation of the deep-forked species were aligned with the between-species maximum variation axis of non deep-forked species. Thus, we are presenting evidence of amplified divergence via the co-option and reorientation of allometric shape variation involved in a sexual selection process that repeatedly drove morphology along a historically favoured direction of cladogenetic evolution.

Male terminalia morphology of sixteen species of the Drosophila saltans group Sturtevant (Diptera, Drosophilidae)

Zootaxa ◽  
2021 ◽  
Vol 5061 (3) ◽  
pp. 523-544
Author(s):  
BRUNA EMILIA ROMAN ◽  
LILIAN MADI-RAVAZZI
Keyword(s):  
Sexual Selection ◽  
Sibling Species ◽  
Potential Role ◽  
Rapid Evolution ◽  
Variable Structure ◽  
Diagnostic Feature ◽  
Internal Fertilization ◽  
Saltans Group

Male terminalia in insects with internal fertilization evolve more rapidly than other structures. The aedeagus is the most variable structure, making it a valuable diagnostic feature to distinguish species. The saltans group Sturtevant of Drosophila Fallén contains sibling species, that can be distinguished by their aedeagi. Here, we revised and illustrated the morphology of the male terminalia of the following species: Drosophila prosaltans Duda, 1927; D. saltans Sturtevant, 1916; D. lusaltans Magalhães, 1962; D. austrosaltans Spassky, 1957; D. septentriosaltans Magalhães, 1962; D. nigrosaltans Magalhães, 1962; D. pseudosaltans Magalhães, 1956; D. sturtevanti Duda, 1927; D. lehrmanae Madi-Ravazzi et al., 2021; D. dacunhai Mourão & Bicudo, 1967; D. milleri Magalhães, 1962; D. parasaltans Magalhães, 1956; D. emarginata Sturtevant, 1942; D. neoelliptica Pavan & Magalhães in Pavan, 1950; D. neosaltans Pavan & Magalhães in Pavan, 1950 and D. neocordata Magalhães, 1956. We found that phallic structures (e.g., the aedeagus) evolve more rapidly than periphallic structures (e.g., epandrium), being completely different among the subgroups and within them. This rapid evolution may be due to the action of sexual selection or to the potential role of those structures in speciation.  

scholarly journals Adiposity, compared with masculinity, serves as a more valid cue to immunocompetence in human mate choice

2013 ◽  
Vol 280 (1751) ◽  
pp. 20122495 ◽  
Author(s):  
Markus J. Rantala ◽  
Vinet Coetzee ◽  
Fhionna R. Moore ◽  
Ilona Skrinda ◽  
Sanita Kecko ◽  
...  
Keyword(s):  
Mate Choice ◽  
Female Mate Choice ◽  
Good Genes ◽  
Secondary Sexual Traits ◽  
Genetic Quality ◽  
Secondary Sexual Trait ◽  
Sexual Traits ◽  
Handicap Hypothesis ◽  
The Relationship ◽  
Secondary Sexual

According to the ‘good genes’ hypothesis, females choose males based on traits that indicate the male's genetic quality in terms of disease resistance. The ‘immunocompetence handicap hypothesis’ proposed that secondary sexual traits serve as indicators of male genetic quality, because they indicate that males can contend with the immunosuppressive effects of testosterone. Masculinity is commonly assumed to serve as such a secondary sexual trait. Yet, women do not consistently prefer masculine looking men, nor is masculinity consistently related to health across studies. Here, we show that adiposity, but not masculinity, significantly mediates the relationship between a direct measure of immune response (hepatitis B antibody response) and attractiveness for both body and facial measurements. In addition, we show that circulating testosterone is more closely associated with adiposity than masculinity. These findings indicate that adiposity, compared with masculinity, serves as a more important cue to immunocompetence in female mate choice.

scholarly journals Impact of trait exaggeration on sex-biased gene expression and genome architecture in a water strider

2020 ◽  
Author(s):  
William Toubiana ◽  
David Armisén ◽  
Corentin Dechaud ◽  
Roberto Arbore ◽  
Abderrahman Khila
Keyword(s):  
Gene Expression ◽  
Sexual Selection ◽  
Enrichment Analysis ◽  
Purifying Selection ◽  
Genome Architecture ◽  
Water Strider ◽  
Secondary Sexual Traits ◽  
Specific Trait ◽  
Sexual Traits ◽  
Secondary Sexual

AbstractExaggerated secondary sexual traits are widespread in nature and often evolve under strong directional sexual selection. Although heavily studied from both theoretical and empirical viewpoints, we have little understanding of how sexual selection influences sex-biased gene regulation during the development of sex-specific phenotypes, and how these changes are reflected in genomic architecture. This is primarily due to the lack of a representative genome and transcriptomes to study the development of secondary sexual traits. Here we present the genome and developmental transcriptomes, focused on the legs of the water strider Microvelia longipes, a species where males exhibit strikingly long third legs used as weapons. The quality of the genome assembly is such that over 90% of the sequence is captured in 13 scaffolds. The most exaggerated legs in males were particularly enriched in sex-biased genes, indicating a specific signature of gene expression in association with sex-specific trait exaggeration. We also found that male-biased genes showed patterns of fast evolution compared to non-biased and female-biased genes, indicative of directional or relaxed purifying selection. Interestingly, we found that female-biased genes that are expressed in the third legs only, but not male-biased genes, were over-represented in the X chromosome compared to the autosomes. An enrichment analysis for sex-biased genes along the chromosomes revealed that they can arrange in large genomic regions or in small clusters of two to four consecutive genes. The number and expression of these enriched regions were often associated with the exaggerated legs of males, suggesting a pattern of common regulation through genomic proximity in association with trait exaggeration. Our findings shed light on how directional sexual selection drives sex-biased gene expression and genome architecture along the path to trait exaggeration and sexual dimorphism.

3. Choosing from the field of competitors

2018 ◽  
pp. 34-51
Author(s):  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Animal Species ◽  
Theoretical Models ◽  
Mating Preferences ◽  
Contemporary View ◽  
Sexual Characteristics ◽  
Sexual Traits ◽  
Secondary Sexual

There is now unequivocal evidence for Darwin’s long-rejected suggestion that females choose among potential mates based on their secondary sexual traits. This has shifted attention from the question of whether females exercised mate choice, to why they should exhibit the mating preferences they do. ‘Choosing from the field of competitors’ gives a contemporary view of mate choice and its occurrence in a wide variety of animal species, along with some examples of what females are choosing and why parasites and disease may play a role in the evolution of extravagant secondary sexual characteristics. Several theoretical models are discussed along with the role of sexual selection in the evolution of humans.

Sexual dimorphism and condition dependence in the anal pad of the small Indian mongoose (Herpestes auropunctatus)

2015 ◽  
Vol 93 (5) ◽  
pp. 397-402
Author(s):  
M.A. Owen ◽  
D.C. Lahti
Keyword(s):  
Sexual Selection ◽  
Sexual Dimorphism ◽  
Indirect Evidence ◽  
Condition Dependence ◽  
Secondary Sexual Traits ◽  
Herpestes Auropunctatus ◽  
Sexual Traits ◽  
Indian Mongoose ◽  
Small Indian Mongoose ◽  
Secondary Sexual

Secondary sexual traits tend to be sexually dimorphic, and theory predicts that such traits should also be condition-dependent in a sex-specific manner. We investigate these phenomena in a field study of the small Indian mongoose (Herpestes auropunctatus (Hodgson, 1836); formerly Herpestes javanicus (É. Geoffroy Saint-Hillaire, 1818)), in the first attempt at understanding secondary sexual traits and sexual selection in this species. Small Indian mongooses are solitary and nonterritorial, and they likely depend on chemical (scent) rather than visual or acoustic signals for communication. Additionally, they possess a fleshy projection around their anus, the anal pad, thought to aid in scent-marking. Our results revealed strong male-biased sexual dimorphism in mass, skull and body lengths, canine diameters, and anal pad area. After controlling for the influence of body length, males were 31% heavier and possessed anal pads that were 68% larger than females’. Additionally, anal pad size was positively related to body size in males but not in females and was condition-dependent in males but not in females. Taken together, our findings provide indirect evidence that the anal pad might have evolved, at least in part, via sexual selection.

scholarly journals The Influence of Applicant and Reviewer Gender on Resident Selection for Internal Medicine

2021 ◽  
Vol 8 ◽  
pp. 238212052110165
Author(s):  
Steven J Katz
Keyword(s):  
Internal Medicine ◽  
Gender Bias ◽  
Potential Role ◽  
Selection Process ◽  
Expected Number ◽  
Internal Medicine Residency Program ◽  
Selection For ◽  
Resident Selection ◽  
Component Scores

Background: While gender bias in medicine, including physician training, has been well described, less is known about gender bias in the selection process for post graduate residency training programs. This analysis reviews the potential role of gender on resident selection for an internal medicine residency program. Methods: File review and interview overall and component scores were analyzed based on the gender of the applicant. File review scores were further analyzed based on the reviewer’s gender. Results: Women applicants scored higher than men applicants on their file review. There were no differences in any one component score except for leadership in art. Women file reviewers scored applicants higher than men file reviewers, but there was no difference between gender scores. There was no difference in overall or component interview scores between men or women applicants. Scoring did not impact the expected rank performance of applicants based on gender at any stage of the selection process. Conclusions: While higher scores were observed in women applicants upon their file review, and women reviewers provided higher file review scores, this did not appear to impact the expected number of women and men applicants at each stage of the applicant process. This suggests a potential lack of gender bias at these stages of applicant selection.

scholarly journals It is not always about body size: evidence of Rensch's rule in a male weapon

2021 ◽  
Vol 17 (6) ◽  
pp. 20210234
Author(s):  
Glauco Machado ◽  
Bruno A. Buzatto ◽  
Diogo S. M. Samia
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Potential Role ◽  
Empirical Studies ◽  
Condition Dependence ◽  
Rensch’S Rule ◽  
Evolutionary Pattern ◽  
Rensch's Rule ◽  
Original Proposal

In many species, sexual dimorphism increases with body size when males are the larger sex but decreases when females are the larger sex, a macro-evolutionary pattern known as Rensch's rule (RR). Although empirical studies usually focus exclusively on body size, Rensch's original proposal included sexual differences in other traits, such as ornaments and weapons. Here, we used a clade of harvestmen to investigate whether two traits follow RR: body size and length of the fourth pair of legs (legs IV), which are used as weapons in male–male fights. We found that males were slightly smaller than females and body size did not follow RR, whereas legs IV were much longer in males and followed RR. We propose that sexual selection might be stronger on legs IV length than on body size in males, and we discuss the potential role of condition dependence in the emergence of RR.

scholarly journals Sperm form and function: what do we know about the role of sexual selection?

Reproduction ◽  
2018 ◽  
Vol 155 (5) ◽  
pp. R229-R243 ◽  
Author(s):  
Stefan Lüpold ◽  
Scott Pitnick
Keyword(s):  
Sexual Selection ◽  
Sperm Morphology ◽  
Swimming Velocity ◽  
Secondary Sexual Traits ◽  
Form And Function ◽  
Biophysical Studies ◽  
Evolutionary Context ◽  
Sexual Selection Theory ◽  
And Function

Sperm morphological variation has attracted considerable interest and generated a wealth of predominantly descriptive studies over the past three centuries. Yet, apart from biophysical studies linking sperm morphology to swimming velocity, surprisingly little is known about the adaptive significance of sperm form and the selective processes underlying its tremendous diversification throughout the animal kingdom. Here, we first discuss the challenges of examining sperm morphology in an evolutionary context and why our understanding of it is far from complete. Then, we review empirical evidence for how sexual selection theory applies to the evolution of sperm form and function, including putative secondary sexual traits borne by sperm.

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