The effect of sex ratio on size-assortative mating in two explosively breeding anurans

2015 ◽  
Vol 36 (2) ◽  
pp. 149-154 ◽  
Author(s):  
Jiří Vojar ◽  
Petr Chajma ◽  
Oldřich Kopecký ◽  
Vladimír Puš ◽  
Miroslav Šálek
Keyword(s):  
Sex Ratio ◽  
Assortative Mating ◽  
Rana Temporaria ◽  
Bufo Bufo ◽  
The Body ◽  
Operational Sex Ratio ◽  
Wild Populations ◽  
Individual Fitness ◽  
Widespread Phenomenon ◽  
Males And Females

Size-assortative mating (SAM) is a widespread phenomenon related to individual fitness. In our study, we examined: (i) the appearance of SAM, and (ii) the effect of sex ratio on intensity of SAM in wild populations of two explosively breeding anurans, common frogs,Rana temporaria, and common toads,Bufo bufo. Despite a higher male-biased operational sex ratio (OSR) in toads, the body lengths of the paired males and females were significantly correlated only in frogs. Increasing male-male competition, assessed via the OSR, resulted in a stronger correlation also in frogs only. Thus, great variability in the presence and intensity of SAM has been observed within both studied species.

Studies on Temperature Regulation

1946 ◽  
Vol 22 (3-4) ◽  
pp. 213-220
Author(s):  
R. L. KIRK ◽  
LANCELOT HOGBEN
Keyword(s):  
Body Temperature ◽  
Rana Temporaria ◽  
Large Body ◽  
Bufo Bufo ◽  
Thermal Capacity ◽  
The Body ◽  
External Temperature ◽  
Terrestrial Vertebrates ◽  
Temperature And Humidity ◽  
Frog Rana Temporaria

1. The upper thermal death-point of the slow worm (Anguis fragilis) is significantly above that of either the toad (Bufo bufo) or the frog (Rana temporaria). That of the toad differs only slightly from that of the frog. 2. In response to external variation with respect to temperature and humidity, the body temperature of the toad behaves in a manner similar to that of the frog, being considerably below that of the air at low humidities, though appreciably above that of the wet-bulb thermometer. It is concluded that the toad loses water as freely as the frog. 3. The body temperature of the slow worm and that of the alligator (A. mississippiensis) differs only slightly from that of the air under all conditions of sustained air temperature and humidity. 4. The body temperature reaction of the alligator is more sluggish than that of the slow worm, presumably owing to the higher thermal capacity of the animal. 5. The significance of these results in relation to the evolution of the terrestrial vertebrates is discussed. It is suggested that homoeothermic stocks could arise only from reptiles of relatively small size, and that large body size would militate against survival during periods of low mean external temperature.

Long-term survival, length of breeding season, and operational sex ratio in a boreal population of common frogs, Rana temporaria L.

1990 ◽  
Vol 68 (1) ◽  
pp. 121-127 ◽  
Author(s):  
Johan Elmberg
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Rana Temporaria ◽  
Return Rate ◽  
Operational Sex Ratio ◽  
Adult Males ◽  
Term Survival ◽  
Size Dependent ◽  
Survival Selection

A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden. Annual return rate averaged 31% (range 16–51%) in males and 16% (range 5–33%) in females. Return rate was not size dependent but increased with every successful previous hibernation, indicating an increased survival rate with age. Return rate was not correlated with winter harshness. Once adult, males had on average 1.5 (maximum 6) seasons with the possibility of reproducing. Corresponding values for females were 1.4 and 4. Mean length of the breeding season was 20 (SD = 2) days. Calling generally started at water temperatures below 3 °C. The lowest spawning temperature was 1 °C. Average temperatures at spawning onset and peak spawning were 5 and 6 °C, respectively. Large males tended to arrive earlier at the pond than small males. Males arrived earlier and stayed longer than did females. The overall population sex ratio was close to unity. The operational sex ratio (OSR) varied during the breeding season, averaging 0.54 (one female to two males). No male was observed to mate more than once per season. I argue that survival selection is more important to male lifetime mating success than is competition in the breeding pond (sexual selection as affected by OSR and length of the breeding season).

scholarly journals Investigating the interaction between inter-locus and intra-locus sexual conflict using hemiclonal analysis in Drosophila melanogaster

2021 ◽  
Author(s):  
Manas Geeta Arun ◽  
Tejinder Singh Chechi ◽  
Rakesh Meena ◽  
Shradha Dattaraya Bhosle ◽  
Srishti ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Ratio ◽  
Genetic Correlation ◽  
Empirical Evidence ◽  
Sexual Conflict ◽  
Genetic Basis ◽  
Operational Sex Ratio ◽  
Female Fitness ◽  
Male And Female ◽  
Males And Females

Divergence in the evolutionary interests of males and females leads to sexual conflict. Traditionally, sexual conflict has been classified into two types: inter-locus sexual conflict (IeSC) and intra-locus sexual conflict (IaSC). IeSC is modeled as a conflict over outcomes of intersexual reproductive interactions mediated by loci that are sex-limited in their effects. IaSC is thought to be a product of selection acting in opposite directions in males and females on traits with a common underlying genetic basis. While in their canonical formalisms IaSC and IeSC are mutually exclusive, there is growing support for the idea that the two may interact. Empirical evidence for such interactions, however, is limited. Here, we investigated the interaction between IeSC and IaSC in Drosophila melanogaster. Using hemiclonal analysis, we sampled 39 hemigenomes from a laboratory-adapted population of D. melanogaster. We measured the contribution of each hemigenome to adult male and female fitness at three different intensities of IeSC, obtained by varying the operational sex-ratio. Subsequently, we estimated the intensity of IaSC at each sex-ratio by calculating the intersexual genetic correlation for fitness and the proportion of sexually antagonistic fitness-variation. Our results indicate a statistically non-significant trend suggesting that increasing the strength of IeSC ameliorates IaSC in the population.

Patterns of Gonadic Development and Operational Sex Ratio Promote Promiscuity of Euxesta bilimeki (Diptera:Ulidiidae)

2020 ◽  
Author(s):  
Christian L Rodríguez-Enríquez ◽  
Diana Pérez-Staples ◽  
Oscar Rios-Cardenas ◽  
Juan Rull
Keyword(s):  
Sex Ratio ◽  
Protein Content ◽  
Operational Sex Ratio ◽  
Mating Frequency ◽  
Body Protein ◽  
Protein Ingestion ◽  
Full Complement ◽  
Individual Mating ◽  
Males And Females ◽  
Testes Size

Abstract Promiscuous mating systems are widely distributed among animals and can be promoted by operational sex ratios (number of receptive adults; OSR). In populations where OSR is not biased towards any sex, the possibility that males and females mate with several individuals increases. For both sexes to synchronize in time and space for reproduction, adults should possess or simultaneously acquire nutrients required to reach sexual maturity. Among synovigenic (without a full complement of eggs at eclosion) species, nutrient acquisition, protein in particular, may influence the OSR. In the Agave fly Euxesta bilimeki (Hendel) (Diptera: Ulidiidae), both sexes engage in multiple mating and females frequently expel all or part of the ejaculate. Here, we assessed the effect of protein intake on gonadic development, and estimated OSR from field-collected individuals. Body protein content was compared between wild and laboratory individuals with access to different diets, and mating frequency and individual mating rate were analyzed for cohorts at a 1:1 sex ratio. Both sexes required protein ingestion for gonadic development, but there were no differences in protein content between field-collected males and males fed protein and sugar in the laboratory, despite the fact that males assigned 9.3% of their corporal weight to testicles. Euxesta bilimeki is a promiscuous species where both males and females mate multiply with one or several individuals in short periods of time; thus, large testes size may be linked to the need of voluminous ejaculate production, and might be further exacerbated by female ejaculate expulsion.

Sociosexuality and sex ratio: Sex differences and local markets

2005 ◽  
Vol 28 (2) ◽  
pp. 288-288
Author(s):  
John Lazarus
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Local Level ◽  
Psychological Effects ◽  
Operational Sex Ratio ◽  
Know How ◽  
Males And Females ◽  
Mating Market ◽  
The Relationship ◽  
Ratio Measure

Operational sex ratio (OSR) is the correct sex ratio measure for predicting sociosexuality, but it is unclear whether this is the measure used. It would be valuable to know how OSR and sociosexuality correlate separately for males and females. The relationship between sociosexuality and OSR should also be examined with OSR measured at the local level of the mating market, where sex ratio must be having its psychological effects.

Short term changes in sex ratio and density alter coercive male mating tactics

Behaviour ◽  
2010 ◽  
Vol 147 (11) ◽  
pp. 1431-1442 ◽  
Author(s):  
James Cureton II ◽  
Raelynn Deaton ◽  
Rachel Martin
Keyword(s):  
Sex Ratio ◽  
Reproductive Activity ◽  
Operational Sex Ratio ◽  
Mating Frequency ◽  
Male Mating ◽  
Mating Tactics ◽  
Short Term ◽  
Classic Theory ◽  
Males And Females ◽  
The Impact

AbstractShort term fluctuations in operational sex ratio (OSR) and density can strongly influence male mating, often exacerbating conflict between males and females. Livebearing fishes of the genus Gambusia are ideal for investigating sexual conflict because males of all sizes mate coercively. In this study, we tested how short-term fluctuations in OSR and density influence coercive male mating behaviours. Specifically, we tested the prediction that as OSR becomes more female biased, males will mate with all available females. In contrast, as OSR becomes more male biased, male aggression will inhibit mating frequency. As predicted, males mated with more females as the number of available females increased. Moreover, males were less aggressive as the proportion of females increased and more aggressive as the number of males increased. This resulted in an inverse relationship between mating and aggression with OSR and density. Coercive males attempt to maximize their reproductive success by mating with all available females, which supports classic theory on the impact of OSR and density on reproductive activity.

scholarly journals Shared environmental effects bias phenotypic estimates of assortative mating in a wild bird

2018 ◽  
Vol 14 (7) ◽  
pp. 20180106 ◽  
Author(s):  
Barbara Class ◽  
Jon E. Brommer
Keyword(s):  
Assortative Mating ◽  
Wild Populations ◽  
Morphometric Traits ◽  
Shared Environmental Effect ◽  
Males And Females ◽  
Statistical Approaches ◽  
Residual Covariance ◽  
Blue Tits ◽  
Term Data

Assortative mating is pervasive in wild populations and commonly described as a positive correlation between the phenotypes of males and females across mated pairs. This correlation is often assumed to reflect non-random mate choice based on phenotypic similarity. However, phenotypic resemblance between mates can also arise when their traits respond plastically to a shared environmental effect creating a (within-pair) residual correlation in traits. Using long-term data collected in pairs of wild blue tits and a covariance partitioning approach, we empirically demonstrate that such residual covariance indeed exists and can generate phenotypic correlations (or mask assortative mating) in behavioural and morphometric traits. These findings (i) imply that residual covariance is likely to be common and bias phenotypic estimates of assortative mating, which can have consequences for evolutionary predictions, (ii) call for the use of rigorous statistical approaches in the study of assortative mating, and (iii) show the applicability of one of these approaches in a common study system.

scholarly journals Sex ratio of breeding Common toads (Bufo bufo) – influence of survival and skipped breeding

2010 ◽  
Vol 31 (4) ◽  
pp. 509-524 ◽  
Author(s):  
Thomas Madsen ◽  
Jon Loman
Keyword(s):  
Sex Ratio ◽  
Deterministic Model ◽  
Breeding Site ◽  
Breeding Population ◽  
Bufo Bufo ◽  
Adult Males ◽  
Breeding Sites ◽  
Lower Survival Rate ◽  
Biased Sex Ratio ◽  
Males And Females

AbstractAnuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not breeding) of the females skipped breeding seasons, whereas the corresponding estimate for males was less than 5%. Yearly survival averaged 42% for adult female and 63% for adult male toads. First year adult males and females had a lower survival rate than older toads. Our results demonstrate that both a female biased mortality rate and a higher proportion of skipped breeding in females contribute to the observed male biased sex ratio. However, a deterministic model suggests other factors may also be involved to obtain this degree of male biased sex ratio, the most likely being that females mature at a later age than male toads.

The influence of operational sex ratio on reproductive success in male sheepshead minnow (Cyprinodon variegatus)

Behaviour ◽  
2020 ◽  
Vol 158 (1) ◽  
pp. 19-34
Author(s):  
Timothy Paciorek ◽  
Michael McQuillan ◽  
Layla Al-Shaer ◽  
Andrew Bloch ◽  
Zachary Carroll ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Sex Ratio ◽  
Experimental Tests ◽  
Reproductive Behaviour ◽  
Operational Sex Ratio ◽  
Territory Size ◽  
Cyprinodon Variegatus ◽  
Aggressive Male ◽  
Males And Females ◽  
Spawning Sites

Abstract Operational sex ratio (OSR) is predicted to influence the direction and intensity of sexual selection. Thus, as the relative numbers of reproductively active males vs females change, the behavioural competition among males and their differences in reproductive success are also predicted to change. While these outcomes seem intuitively obvious, there have been few experimental tests that examine these predictions. Here, we experimentally tested the relationship between OSR and reproductive behaviour in sheepshead minnows (Cyprinodon variegatus) competing in laboratory-based pools. Males and females were assigned to one of three OSRs (female-biased, equal, or male-biased). We monitored aggression, territory size, and number of eggs acquired by the most aggressive male, termed the “focal male,” in the pool. We used microsatellite analyses to determine the parentage of the eggs within the focal males’ territories. Focal males, by definition, were the most aggressive individual in their pools, but the degree of their aggressiveness and number of spawning sites they controlled were not influenced by OSR. Compared to focal males in the equal and male-biased OSRs, focal males in the female-biased OSR did receive more eggs but the OSR did not appear to influence the percentage of eggs they fathered on their own spawning sites. We speculate that a focal male’s competitive ability is more important to reproductive success than the number of other males and females present.

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