scholarly journals Experimental evidence for the role of sexual selection in the evolution of cuticular hydrocarbons in the dung beetle, Onthophagus taurus

2019 ◽  
Vol 32 (11) ◽  
pp. 1186-1193 ◽  
Author(s):  
Jacob D. Berson ◽  
Francisco Garcia‐Gonzalez ◽  
Leigh W. Simmons
Keyword(s):  
Sexual Selection ◽  
Experimental Evidence ◽  
Cuticular Hydrocarbons ◽  
Dung Beetle ◽  
Onthophagus Taurus

scholarly journals Offspring viability benefits but no apparent costs of mating with high quality males

2010 ◽  
Vol 7 (3) ◽  
pp. 419-421 ◽  
Author(s):  
Leigh W. Simmons ◽  
Rebecca Holley
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Alternative Hypothesis ◽  
Dung Beetle ◽  
Male Courtship ◽  
High Quality ◽  
Female Resistance ◽  
Genetic Quality ◽  
Onthophagus Taurus ◽  
Courtship Signals

Traditional models of sexual selection posit that male courtship signals evolve as indicators of underlying male genetic quality. An alternative hypothesis is that sexual conflict over mating generates antagonistic coevolution between male courtship persistence and female resistance. In the scarabaeine dung beetle Onthophagus taurus , females are more likely to mate with males that have high courtship rates. Here, we examine the effects of exposing females to males with either high or low courtship rates on female lifetime productivity and offspring viability. Females exposed to males with high courtship rates mated more often and produced offspring with greater egg–adult viability. Female productivity and lifespan were unaffected by exposure to males with high courtship rates. The data are consistent with models of sexual selection based on indirect genetic benefits, and provide little evidence for sexual conflict in this system.

scholarly journals A link between heritable parasite resistance and mate choice in dung beetles

2019 ◽  
Vol 30 (5) ◽  
pp. 1382-1387 ◽  
Author(s):  
Bruno A Buzatto ◽  
Janne S Kotiaho ◽  
Larissa A F Assis ◽  
Leigh W Simmons
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Female Choice ◽  
Additive Genetic Variance ◽  
Dung Beetle ◽  
Mite Infestation ◽  
Adult Survival ◽  
Parasite Resistance ◽  
Onthophagus Taurus ◽  
Sexual Selection Theory

AbstractParasites play a central role in the adaptiveness of sexual reproduction. Sexual selection theory suggests a role for parasite resistance in the context of mate choice, but the evidence is mixed. The parasite-mediated sexual selection (PMSS) hypothesis derives a number of predictions, among which that resistance to parasites is heritable, and that female choice favors parasite resistance genes in males. Here, we tested the PMSS hypothesis using the dung beetle Onthophagus taurus, a species that can be heavily parasitized by Macrocheles merdarius mites, which are known to affect adult survival. We investigated the heritability of resistance to M. merdarius, as well as whether female O. taurus impose a mating bias against males susceptible to mite infestation. Female choice for parasite resistance is difficult to disentangle from the possibility that females are simply choosing less parasitized males due to naturally selected benefits of avoiding contracting those parasites. This is especially likely for ectoparasites, such as mites. We tackled this problem by performing a mate choice trial first, and then measuring a male’s resistance to mite infestation. Resistance to mite infestation exhibited significant levels of additive genetic variance. Although we found no relationship between mating success and parasite resistance, males with greater resistance to infestation mated for longer. If females control copula duration, given that short copulations often result in mating failure, female choice could act on parasite resistance.

Allometric relationships and character evolution in Onthophagus taurus (Coleoptera: Scarabaeidae)

2000 ◽  
Vol 78 (7) ◽  
pp. 1199-1206 ◽  
Author(s):  
Claudia Palestrini ◽  
Antonio Rolando ◽  
Paola Laiolo
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Small Body ◽  
Dung Beetle ◽  
Allometric Relationships ◽  
Secondary Sexual Traits ◽  
Onthophagus Taurus ◽  
Sexual Traits ◽  
External Body ◽  
Secondary Sexual

Allometric relationships in primary sexual traits (male and female genitalia), secondary sexual traits (male horns and female carinae), and non-sex-related traits (external body traits, epipharynx traits) were studied in the dung beetle Onthophagus taurus. Model II regressions of log-transformed data were used to quantify relationships, with pronotum width as regressor and indicator of overall body size. Slopes (allometric values) for the different trait categories were significantly different, with secondary sexual traits showing the highest values (higher than 1.0), followed by external body traits (slightly lower than 1.00) and epipharynx traits (around 0.2). Primary sexual traits and body size were mostly uncorrelated and genital sizes were virtually constant. Allometries of secondary sexual traits were quite different in the two sexes: the relationship between male horn length and pronotum width was approximately sigmoidal, while that between female carina length and pronotum width was linear. External body traits had significantly higher allometric values in females than in males. Our results suggest that traits in the different categories are under different kinds of selection. Genital allometries can be explained on the basis of sexual selection by cryptic female choice or by the lock-and-key hypothesis. Among secondary sexual characters, male horn morphology seems to be mostly "environmentally" determined and sexual selection would affect only a component of the developmental mechanism of horn expression. External body characters are likely under natural selection, even though a few traits could be sex-related. Finally, in both sexes, internal epipharynx traits seem to be subject to the same selective pressure, probably because males and females use the same feeding niche. The constancy of genital sizes in O. taurus suggests that in developmental processes, more is invested in primary sexual traits (to produce genitalia of the proper size) than in secondary sexual or body traits. Males receiving low quantities of food may incur costs associated with a small horn or small body size, but do not incur costs associated with small genitalia. Females probably share the same developmental pattern.

scholarly journals Can Sexual Selection Drive the Evolution of Sperm Cell Structure?

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1227
Author(s):  
Leigh W. Simmons ◽  
Francisco Garcia-Gonzalez
Keyword(s):  
Sexual Selection ◽  
Sperm Cell ◽  
Cell Structure ◽  
Dung Beetle ◽  
Divergent Evolution ◽  
Cell Phenotype ◽  
Sperm Cells ◽  
Sperm Length ◽  
Comparative Analyses ◽  
Onthophagus Taurus

Sperm cells have undergone an extraordinarily divergent evolution among metazoan animals. Parker recognized that because female animals frequently mate with more than one male, sexual selection would continue after mating and impose strong selection on sperm cells to maximize fertilization success. Comparative analyses among species have revealed a general relationship between the strength of selection from sperm competition and the length of sperm cells and their constituent parts. However, comparative analyses cannot address causation. Here, we use experimental evolution to ask whether sexual selection can drive the divergence of sperm cell phenotype, using the dung beetle Onthophagus taurus as a model. We either relaxed sexual selection by enforcing monogamy or allowed sexual selection to continue for 20 generations before sampling males and measuring the total length of sperm cells and their constituent parts, the acrosome, nucleus, and flagella. We found differences in the length of the sperm cell nucleus but no differences in the length of the acrosome, flagella, or total sperm length. Our data suggest that different sperm cell components may respond independently to sexual selection and contribute to the divergent evolution of these extraordinary cells.

TESTING GOAL-DRIVEN CAPTURE BY THREAT

2019 ◽  
Author(s):  
Chris Robert Harrison Brown
Keyword(s):  
Experimental Evidence ◽  
Attentional Capture ◽  
Critical Role ◽  
Experimental Manipulation ◽  
Contingent Capture ◽  
Top Down ◽  
Affective Stimuli ◽  
Clinical Disorders ◽  
Positive Stimuli

Attention has long been characterised within prominent models as reflecting a competition between goal-driven and stimulus-driven processes. It remains unclear, however, how involuntary attentional capture by affective stimuli, such as threat-laden content, fits into such models. While such effects were traditionally held to reflect stimulus-driven processes, recent research has increasingly implicated a critical role of goal-driven processes. Here we test an alternative goal-driven account of involuntary attentional capture by threat, using an experimental manipulation of goal-driven attention. To this end we combined the classic ‘contingent capture’ and ‘emotion-induced blink’ (EIB) paradigms in an RSVP task with both positive or threatening target search goals. Across six experiments, positive and threat distractors were presented in peripheral, parafoveal, and central locations. Across all distractor locations, we found that involuntary attentional capture by irrelevant threatening distractors could be induced via the adoption of a search goal for a threatening category; adopting a goal for a positive category conversely led to capture only by positive stimuli. Our findings provide direct experimental evidence for a causal role of voluntary goals in involuntary capture by irrelevant threat stimuli, and hence demonstrate the plausibility of a top-down account of this phenomenon. We discuss the implications of these findings in relation to current cognitive models of attention and clinical disorders.

The Role of Legal Justiication in Judicial Performance: Quasi-Experimental Evidence

2018 ◽  
Author(s):  
Paige Marta Skiba ◽  
Alessandro Melcarne ◽  
Giovanni Battista Ramello
Keyword(s):  
Experimental Evidence ◽  
Quasi Experimental ◽  
Judicial Performance

scholarly journals Wood Pastures: A Transitional Habitat between Forests and Pastures for Dung Beetle Assemblages

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
László Somay ◽  
Viktor Szigeti ◽  
Gergely Boros ◽  
Réka Ádám ◽  
András Báldi
Keyword(s):  
Functional Group ◽  
Animal Health ◽  
Habitat Type ◽  
Dung Beetle ◽  
Dung Beetles ◽  
Livestock Grazing ◽  
Pitfall Traps ◽  
Assemblage Composition ◽  
Beetle Assemblages

Wood pastures are home to a variety of species, including the dung beetle. Dung beetles are an important functional group in decomposition. Specifically, in terms of livestock manure, they not only contribute to nutrient cycling but are key players in supporting human and animal health. Dung beetles, however, are declining in population, and urgent recommendations are needed to reverse this trend. Recommendations need to be based on solid evidence and specific habitats. Herein, we aimed to investigate the role of an intermediate habitat type between forests and pastures. Wood pastures are key areas for dung beetle conservation. For this reason, we compared dung beetle assemblages among forests, wood pastures, and grasslands. We complemented this with studies on the effects of dung type and season at three Hungarian locations. Pitfall traps baited with cattle, sheep, or horse dung were used in forests, wood pastures, and pasture habitats in spring, summer, and autumn. Dung beetle assemblages of wood pastures showed transient characteristics between forests and pastures regarding their abundance, species richness, Shannon diversity, assemblage composition, and indicator species. We identified a strong effect of season and a weak of dung type. Assemblage composition proved to be the most sensitive measure of differences among habitats. The conservation of dung beetles, and the decomposition services they provide, need continuous livestock grazing to provide fresh dung, as well as the maintenance of wood pastures where dung beetle assemblages typical of forests and pastures can both survive.

scholarly journals Experimental evidence of pathogenic role of IgG autoantibodies in IgA nephropathy

2021 ◽  
Vol 118 ◽  
pp. 102593
Author(s):  
Zina Moldoveanu ◽  
Hitoshi Suzuki ◽  
Colin Reily ◽  
Kenji Satake ◽  
Lea Novak ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Iga Nephropathy ◽  
Pathogenic Role
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