scholarly journals Why don't all animals avoid inbreeding?

2021 ◽  
Vol 288 (1956) ◽  
pp. 20211045
Author(s):  
Victoria L. Pike ◽  
Charlie K. Cornwallis ◽  
Ashleigh S. Griffin
Keyword(s):  
Mate Choice ◽  
Inbreeding Depression ◽  
Meta Analysis ◽  
Sexual Partners ◽  
Inbreeding Avoidance ◽  
Animal Kingdom ◽  
Offspring Fitness ◽  
Males And Females

Individuals are expected to avoid mating with relatives as inbreeding can reduce offspring fitness, a phenomenon known as inbreeding depression. This has led to the widespread assumption that selection will favour individuals that avoid mating with relatives. However, the strength of inbreeding avoidance is variable across species and there are numerous cases where related mates are not avoided. Here we test if the frequency that related males and females encounter each other explains variation in inbreeding avoidance using phylogenetic meta-analysis of 41 different species from six classes across the animal kingdom. In species reported to mate randomly with respect to relatedness, individuals were either unlikely to encounter relatives, or inbreeding had negligible effects on offspring fitness. Mechanisms for avoiding inbreeding, including active mate choice, post-copulatory processes and sex-biased dispersal, were only found in species with inbreeding depression. These results help explain why some species seem to care more about inbreeding than others: inbreeding avoidance through mate choice only evolves when there is both a risk of inbreeding depression and related sexual partners frequently encounter each other.

scholarly journals Sexual selection after gamete release in broadcast spawning invertebrates

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200069 ◽  
Author(s):  
Jonathan P. Evans ◽  
Rowan A. Lymbery
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sperm Competition ◽  
Sexual Conflict ◽  
Gamete Release ◽  
Theme Issue ◽  
Animal Kingdom ◽  
External Fertilization ◽  
Broadcast Spawning ◽  
Males And Females

Broadcast spawning invertebrates offer highly tractable models for evaluating sperm competition, gamete-level mate choice and sexual conflict. By displaying the ancestral mating strategy of external fertilization, where sexual selection is constrained to act after gamete release, broadcast spawners also offer potential evolutionary insights into the cascade of events that led to sexual reproduction in more ‘derived’ groups (including humans). Moreover, the dynamic reproductive conditions faced by these animals mean that the strength and direction of sexual selection on both males and females can vary considerably. These attributes make broadcast spawning invertebrate systems uniquely suited to testing, extending, and sometimes challenging classic and contemporary ideas in sperm competition, many of which were first captured in Parker's seminal papers on the topic. Here, we provide a synthesis outlining progress in these fields, and highlight the burgeoning potential for broadcast spawners to provide both evolutionary and mechanistic understanding into gamete-level sexual selection more broadly across the animal kingdom. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals A meta-analysis of factors influencing the strength of mate-choice copying in animals

2020 ◽  
Vol 31 (6) ◽  
pp. 1279-1290 ◽  
Author(s):  
Alice D Davies ◽  
Zenobia Lewis ◽  
Liam R Dougherty
Keyword(s):  
Mate Choice ◽  
Measure Theory ◽  
Meta Analysis ◽  
Empirical Work ◽  
Reproductive Investment ◽  
Mate Choice Copying ◽  
Factors Influencing ◽  
Before And After ◽  
Taxonomic Range ◽  
Males And Females

Abstract Mate-choice copying is a form of social learning in which an individual’s choice of mate is influenced by the apparent choices of other individuals of the same sex and has been observed in more than 20 species across a broad taxonomic range. Though fitness benefits of copying have proven difficult to measure, theory suggests that copying should not be beneficial for all species or contexts. However, the factors influencing the evolution and expression of copying have proven difficult to resolve. We systematically searched the literature for studies of mate-choice copying in nonhuman animals and, then, performed a phylogenetically controlled meta-analysis to explore which factors influence the expression of copying across species. Across 58 published studies in 23 species, we find strong evidence that animals copy the mate choice of others. The strength of copying was significantly influenced by taxonomic group; however, sample size limitations mean it is difficult to draw firm conclusions regarding copying in mammals and arthropods. The strength of copying was also influenced by experimental design: copying was stronger when choosers were tested before and after witnessing a conspecific’s mate choice compared to when choosers with social information were compared to choosers without. Importantly, we did not detect any difference in the strength of copying between males and females or in relation to the rate of multiple mating. Our search also highlights that more empirical work is needed to investigate copying in a broader range of species, especially those with differing mating systems and levels of reproductive investment.

scholarly journals Resolving the conundrum of inbreeding depression but no inbreeding avoidance: Estimating sex-specific selection on inbreeding by song sparrows (Melospiza melodia)

Evolution ◽  
2015 ◽  
Vol 69 (11) ◽  
pp. 2846-2861 ◽  
Author(s):  
Jane M. Reid ◽  
Peter Arcese ◽  
Greta Bocedi ◽  
A. Bradley Duthie ◽  
Matthew E. Wolak ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Inbreeding Avoidance ◽  
Melospiza Melodia ◽  
Song Sparrows

scholarly journals Mycoplasma genitalium incidence, persistence, concordance between partners and progression: systematic review and meta-analysis

2019 ◽  
Vol 95 (5) ◽  
pp. 328-335 ◽  
Author(s):  
Manuel Cina ◽  
Lukas Baumann ◽  
Dianne Egli-Gany ◽  
Florian S Halbeisen ◽  
Hammad Ali ◽  
...  
Keyword(s):  
Systematic Review ◽  
Antimicrobial Resistance ◽  
Meta Analysis ◽  
Age Distribution ◽  
Mycoplasma Genitalium ◽  
Developed Countries ◽  
Sexual Partners ◽  
Risk Of Bias ◽  
Infection Status ◽  
Sexually Transmitted

BackgroundMycoplasma genitalium is increasingly seen as an emerging sexually transmitted pathogen, and has been likened to Chlamydia trachomatis, but its natural history is poorly understood. The objectives of this systematic review were to determine M. genitalium incidence, persistence, concordance between sexual partners and the risk of pelvic inflammatory disease (PID).MethodsWe searched Medline, EMBASE, LILACS, IndMed and African Index Medicus from 1 January 1981 until 17 March 2018. Two independent researchers screened studies for inclusion and extracted data. We examined results in forest plots, assessed heterogeneity and conducted meta-analysis where appropriate. Risk of bias was assessed for all studies.ResultsWe screened 4634 records and included 18 studies; six (4201 women) reported on incidence, five (636 women) on persistence, 10 (1346 women and men) on concordance and three (5139 women) on PID. Incidence in women in two very highly developed countries was 1.07 per 100 person-years (95% CI 0.61 to 1.53, I2 0%). Median persistence of M. genitalium was estimated from one to three months in four studies but 15 months in one study. In 10 studies measuring M. genitalium infection status in couples, 39%–50% of male or female sexual partners of infected participants also had M. genitalium detected. In prospective studies, PID incidence was higher in women with M. genitalium than those without (risk ratio 1.73, 95% CI 0.92 to 3.28, I2 0%, two studies).DiscussionIncidence of M. genitalium in very highly developed countries is similar to that for C. trachomatis, but concordance might be lower. Taken together with other evidence about age distribution and antimicrobial resistance in the two infections, M. genitalium is not the new chlamydia. Synthesised data about prevalence, incidence and persistence of M. genitalium infection are inconsistent. These findings can be used for mathematical modelling to investigate the dynamics of M. genitalium.Registration numbersCRD42015020420, CRD42015020405

scholarly journals Complementary sex determination, inbreeding depression and inbreeding avoidance in a gregarious sawfly

Heredity ◽  
2016 ◽  
Vol 117 (5) ◽  
pp. 326-335 ◽  
Author(s):  
K E Harper ◽  
R K Bagley ◽  
K L Thompson ◽  
C R Linnen
Keyword(s):  
Sex Determination ◽  
Inbreeding Depression ◽  
Inbreeding Avoidance ◽  
Complementary Sex Determination

scholarly journals Problematic alcohol use and reduced hippocampal volume: a meta-analytic review

2017 ◽  
Vol 47 (13) ◽  
pp. 2288-2301 ◽  
Author(s):  
S. Wilson ◽  
J. L. Bair ◽  
K. M. Thomas ◽  
W. G. Iacono
Keyword(s):  
Alcohol Use ◽  
Meta Analysis ◽  
Hippocampal Volume ◽  
Future Research ◽  
Cross Sectional ◽  
Problematic Alcohol ◽  
Analytic Review ◽  
Males And Females ◽  
Clinically Significant ◽  
Problematic Alcohol Use

BackgroundA number of studies reports reduced hippocampal volume in individuals who engage in problematic alcohol use. However, the magnitude of the difference in hippocampal volume between individuals with v. without problematic alcohol use has varied widely, and there have been null findings. Moreover, the studies comprise diverse alcohol use constructs and samples, including clinically significant alcohol use disorders and subclinical but problematic alcohol use (e.g. binge drinking), adults and adolescents, and males and females.MethodsWe conducted the first quantitative synthesis of the published empirical research on associations between problematic alcohol use and hippocampal volume. In total, 23 studies were identified and selected for inclusion in the meta-analysis; effects sizes were aggregated using a random-effects model.ResultsProblematic alcohol use was associated with significantly smaller hippocampal volume (d = −0.53). Moderator analyses indicated that effects were stronger for clinically significant v. subclinical alcohol use and among adults relative to adolescents; effects did not differ among males and females.ConclusionsProblematic alcohol use is associated with reduced hippocampal volume. The moderate overall effect size suggests the need for larger samples than are typically included in studies of alcohol use and hippocampal volume. Because the existing literature is almost entirely cross-sectional, future research using causally informative study designs is needed to determine whether this association reflects premorbid risk for the development of problematic alcohol use and/or whether alcohol has a neurotoxic effect on the hippocampus.

scholarly journals Heightened condition dependent expression of structural colouration in the faces, but not wings, of male and female flies

2021 ◽  
Author(s):  
Thomas E White ◽  
Amy Locke ◽  
Tanya Latty
Keyword(s):  
Mate Choice ◽  
Condition Dependence ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Honest Signals ◽  
Mutual Mate Choice ◽  
Close Range ◽  
Males And Females ◽  
Structural Colouration

Abstract Structurally coloured sexual signals are a conspicuous and widespread class of ornament used in mate choice, though the extent to which they encode information on the quality of their bearers is not fully resolved. Theory predicts that signalling traits under strong sexual selection as honest indicators should evolve to be more developmentally integrated and exaggerated than nonsexual traits, thereby leading to heightened condition dependence. Here we test this prediction through examination of the sexually dimorphic faces and wings of the cursorial fly Lispe cana. Males and females possess structural UV-white and golden faces, respectively, and males present their faces and wings to females during close-range, ground-based courtship displays, thereby creating the opportunity for mutual inspection. Across a field-collected sample of individuals, we found that the appearance of the faces of both sexes scaled positively with individual condition, though along separate axes. Males in better condition expressed brighter faces as modelled according to conspecific flies, whereas condition scaled with facial saturation in females. We found no such relationships for their wing interference pattern nor abdomens, with the latter included as a nonsexual control. Our results suggest that the structurally coloured faces, but not the iridescent wings, of male and female Lispe cana are reliable guides to individual quality and support the broader potential for structural colours as honest signals. They also highlight the potential for mutual mate choice in this system, while arguing for one of several alternate signalling roles for wing interferences patterns among the myriad taxa which bear them.

scholarly journals The incidence of left-handedness: a meta-analysis [1993]

2019 ◽  
Author(s):  
Ian Christopher McManus
Keyword(s):  
Sex Difference ◽  
Meta Analysis ◽  
Birth Cohorts ◽  
Future Studies ◽  
Left Handedness ◽  
Left Handed ◽  
Method Of Measurement ◽  
Males And Females ◽  
Older Subjects ◽  
Unpublished Manuscripts

A meta-analysis is reported of 88 studies, examining 100 study populations, in which the handedness of 284665 individuals has been assessed. The overall incidence of left-handedness was 7.78%. The incidence of left-handedness was not related to the method of measurement, or the length or number of response items included in inventories. Study populations with lower response rates and smaller study populations showed some evidence of higher incidences of left-handedness, presumably due to response biasses. There was no evidence that the incidence of left-handedness was related to the year of publication of studies; however the incidence of left-handedness was lower in older subjects and in those from earlier birth cohorts, the two effects not being statistically distinguishable.Information was available from 64 study populations concerning the incidence of left-handedness in males and females; overall 8.52% of males were left-handed compared with 6.69% of females, the male incidence being 27.4% higher than that in females. Although there was some suggestion that the sex difference was greater in larger studies, and in studies whose main purpose was not the study of handedness, these differences were not significant. It is concluded that the size of the sex difference is unrelated to any of the moderator variables we have studied.It was not possible to carry out a meta-analysis of degree of handedness due to wide-spread differences in the method of reporting of degree of handedness.We recommend that future studies of handedness should, as a minimum, use one of three standard methods of assessment, so that comparison of studies is facilitated. Note: This manuscript was originally prepared in 1993 but due to problems at a major journal, described briefly, was never eventually published. It has however been cited on a number of occasions, and has been available at https://www.ucl.ac.uk/medical-education/publications/unpublished-manuscripts/meta-analysis-of-handedness . A major meta-analysis of handedness in 2019 by another author has now been submitted which cites this manuscript, and therefore it needs to be available in a more archivable format.

scholarly journals Wolbachia promote successful sex with siblings

2019 ◽  
Author(s):  
Zeynab Bagheri ◽  
Ali Asghar Talebi ◽  
Sassan Asgari ◽  
Mohammad Mehrabadi
Keyword(s):  
Inbreeding Depression ◽  
Adult Emergence ◽  
Fertilization Success ◽  
Inbreeding Avoidance ◽  
High Rate ◽  
Avoidance Behaviour ◽  
Female Progeny ◽  
Habrobracon Hebetor ◽  
Sibling Pairs ◽  
Sib Mating

AbstractWolbachia are intracellular α-proteobacteria that have a wide distribution among various arthropods and nematodes. They affect the host reproduction favoring their maternal transmission, which sets up a potential conflict in inbreeding situations when the host avoids sexual reproduction preventing inbreeding depression, while Wolbachia pushes it. In this study, we used the wasp Habrobracon hebetor to test the hypothesis that Wolbachia modulate inbreeding avoidance behaviour and promote sib mating. To test this, we first cured wasps of Wolbachia using tetracycline treatment and produced infected and uninfected isolines. Then, we paired the uninfected and infected females with sibling (inbred) and non-sibling (outbred) males in choice and non-choice experiments. Our results showed no obvious precopulatory inbreeding avoidance in this wasp as brother-sister mating rates (in both choice and nonchoice experiments) were not significantly different form non-sibling pairs, regardless of Wolbachia infection. However, our results indicated that H. hebetor shows a strong postcopulatory inbreeding avoidance behaviour that results in a low fertilization rate of uninfected siblings and therefore high rate of production of male progeny was obtained. We observed higher rates of fertilization success in the Wolbachia-infected lines that resulted in significantly higher female progeny production compared to the uninfected sib mates. Since diploid females are the result of successful fertilization due to haplodiploidy sex determination system in this insect, our results indicate that Wolbachia promoted fertile sib mating in H. hebetor. Interestingly, the rate of adult emergence in the progeny of Wolbachia-infected sib mates were almost similar to the non-sib mate crosses and significantly more than those observed in the uninfected sib mate crosses. We support the idea that Wolbachia modulate inbreeding avoidance and promote sib mating and also mitigate inbreeding depression. The wasp Habrobracon hebetor siblings infected with Wolbachia show higher rates of fertilization success and higher adult emergence rates compared to the uninfected sib mates. By promoting successful sex with siblings and increasing the probability of female progeny, Wolbachia enhance their transmission to the next generation and also mitigate inbreeding depression. This is an undescribed effect of Wolbachia (symbiont) on the host reproduction.

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