scholarly journals Phenotypic and environmental predictors of reproductive success in painted turtles

2020 ◽  
Author(s):  
Jessica M. Judson ◽  
Luke A. Hoekstra ◽  
Kaitlyn G. Holden ◽  
Fredric J. Janzen
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Mate Choice ◽  
Sex Ratio ◽  
Sex Ratios ◽  
Female Mate Choice ◽  
Painted Turtles ◽  
Weak Evidence ◽  
Adult Sex Ratio ◽  
Siring Success

ABSTRACTSexual selection is often assumed to elicit sexually dimorphic traits. However, most work on this assumption in tetrapod vertebrates has focused on birds. In this field experiment, we assessed relationships between both sexually dimorphic (body size, claw length) and non-dimorphic traits (forelimb stripe color, baseline corticosterone concentrations) and reproductive success in adult painted turtles to explicate the roles of these phenotypes in mate choice and the evolution of sexual dimorphism. We also modified adult sex ratios in experimental ponds to elucidate the role of biased sex ratios on reproductive success, which is a timely test of the potential threat of biased sex ratios on population persistence in a species with temperature-dependent sex determination. We found no strong influence of male phenotypes on male siring success, but female body size and baseline corticosterone concentrations predicted female clutch sizes. We find weak evidence that adult sex ratio influences male siring success, with a male-biased sex ratio producing lower male siring success than a female-biased sex ratio. This study offers evidence that female mate choice may not be an important selective force on male phenotypes, but that instead selection occurs on female phenotypes, particularly body size and corticosterone concentrations. Further, biased adult sex ratios can influence reproductive success of both sexes. Finally, the use of Kompetitive Allele Specific PCR (KASP) was highly successful in parentage analysis, which adds reptiles to the growing list of taxa successfully genotyped with this new technology.Lay SummaryFemale painted turtles aren’t choosy about traits of their mates. In a field experiment, we find that male traits do not predict male fitness, but key female traits (body size and stress levels) do predict female reproductive success. Further, we find weak evidence that adult sex ratio influences individual fitness in this species with environmental sex determination. Ultimately, we reject the long-assumed importance of female mate choice in this freshwater turtle.

Unexpected offspring sex ratios in response to habitat quality in a size-dimorphic bark beetle

1999 ◽  
Vol 77 (4) ◽  
pp. 524-529 ◽  
Author(s):  
Risa D Sargent ◽  
Mary L Reid
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Sex Ratio ◽  
Habitat Quality ◽  
Bark Beetle ◽  
Sex Ratios ◽  
Diploid Species ◽  
Differential Mortality ◽  
Male Reproductive Success ◽  
Offspring Sex

Facultative sex ratio manipulation has been examined in a limited number of diploid species, mainly vertebrates. We tested the prediction that mothers would preferentially place males in conditions conducive to large size in the diploid pine engraver bark beetle, Ips pini. In this species, males are the larger sex and therefore male reproductive success was expected to be more dependent on body size than female reproductive success. Because body size is largely environmentally determined in bark beetles, mothers were expected to alter sex ratios in response to habitat quality. Contrary to predictions, offspring sex ratios tended to be more female biased in situations conducive to large offspring size than in situations producing offspring of small size. We were able to rule out nonadaptive explanations such as differential mortality or development times of males and females, suggesting that the observed pattern is adaptive. This study provides a rare example of sex ratio manipulation in diploid insects. However, the unexpected direction of sex ratio biases suggests that daughters gain a yet unknown benefit from being reared in high-quality conditions that surpasses the fitness that would be gained from producing relatively larger sons.

scholarly journals Adult sex ratio influences mate choice in Darwin’s finches

2019 ◽  
Vol 116 (25) ◽  
pp. 12373-12382 ◽  
Author(s):  
Peter R. Grant ◽  
B. Rosemary Grant
Keyword(s):  
Mate Choice ◽  
Sex Ratio ◽  
Phylogenetic Analyses ◽  
Sex Ratios ◽  
Differential Mortality ◽  
Sexual Imprinting ◽  
Darwin's Finches ◽  
Darwin’S Finches ◽  
Adult Sex Ratio ◽  
Geospiza Fortis

The adult sex ratio (ASR) is an important property of populations. Comparative phylogenetic analyses have shown that unequal sex ratios are associated with the frequency of changing mates, extrapair mating (EPM), mating system and parental care, sex-specific survival, and population dynamics. Comparative demographic analyses are needed to validate the inferences, and to identify the causes and consequences of sex ratio inequalities in changing environments. We tested expected consequences of biased sex ratios in two species of Darwin’s finches in the Galápagos, where annual variation in rainfall, food supply, and survival is pronounced. Environmental perturbations cause sex ratios to become strongly male-biased, and when this happens, females have increased opportunities to choose high-quality males. The choice of a mate is influenced by early experience of parental morphology (sexual imprinting), and since morphological traits are highly heritable, mate choice is expressed as a positive correlation between mates. The expected assortative mating was demonstrated when theGeospiza scandenspopulation was strongly male-biased, and not present in the contemporaryGeospiza fortispopulation with an equal sex ratio. Initial effects of parental imprinting were subsequently overridden by other factors when females changed mates, some repeatedly. Females of both species were more frequently polyandrous in male-biased populations, and fledged more offspring by changing mates. The ASR ratio indirectly affected the frequency of EPM (and hybridization), but this did not lead to social mate choice. The study provides a strong demonstration of how mating patterns change when environmental fluctuations lead to altered sex ratios through differential mortality.

scholarly journals Recruitment sex ratios in gray-tailed voles (Microtus canicaudus) in response to density, sex ratio, and season

2003 ◽  
Vol 81 (8) ◽  
pp. 1306-1311 ◽  
Author(s):  
Monica L Bond ◽  
Jerry O Wolff ◽  
Sven Krackow
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Resource Competition ◽  
Sex Ratios ◽  
Female Offspring ◽  
High Population ◽  
Reproductive Value ◽  
High Population Density ◽  
Adult Sex Ratio ◽  
Sex Ratio Adjustment

We tested predictions associated with three widely used hypotheses for facultative sex-ratio adjustment of vertebrates using eight enclosed populations of gray-tailed voles, Microtus canicaudus. These were (i) the population sex ratio hypothesis, which predicts that recruitment sex ratios should oppose adult sex-ratio skews, (ii) the local resource competition hypothesis, which predicts female-biased recruitment at low adult population density and male-biased recruitment at high population density, and (iii) the first cohort advantage hypothesis, which predicts that recruitment sex ratios should be female biased in the spring and male biased in the autumn. We monitored naturally increasing population densities with approximately equal adult sex ratios through the spring and summer and manipulated adult sex ratios in the autumn and measured subsequent sex ratios of recruits. We did not observe any significant sex-ratio adjustment in response to adult sex ratio or high population density; we did detect an influence of time within the breeding season, with more female offspring observed in the spring and more male offspring observed in the autumn. Significant seasonal increases in recruitment sex ratios indicate the capacity of female gray-tailed voles to manipulate their offspring sex ratios and suggest seasonal variation in the relative reproductive value of male and female offspring to be a regular phenomenon.

scholarly journals The combined effects of temperature and aromatase inhibitor on metamorphosis, growth, locomotion, and sex ratio of tiger frog (Hoplobatrachus rugulosus) tadpoles

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8834
Author(s):  
Yun Tang ◽  
Zhi-Qiang Chen ◽  
You-Fu Lin ◽  
Jing-Yi Chen ◽  
Guo-Hua Ding ◽  
...  
Keyword(s):  
Body Size ◽  
Survival Rate ◽  
Sex Ratio ◽  
Aromatase Inhibitor ◽  
Condition Factor ◽  
Sex Ratios ◽  
Control Group ◽  
Treatment Groups ◽  
Effects Of Temperature ◽  
Steroid Hormone Level

Background The tiger frog (Hoplobatrachus rugulosus) is widely raised by many farms in southern region of China as an economically edible frog. The growth, development, and sexual differentiation of amphibians are influenced by temperature and steroid hormone level. However, the problem of hormone residues is caused by the addition of exogenous hormones in frog breeding, it is worth considering whether non-sterol aromatase inhibitors can be used instead of hormones. Methods In our study, H. rugulosus tadpoles were subjected to two water temperatures (29 °C and 34 °C) and three letrozole concentrations in the feed (0, 0.1 and 1 mg/g) to examine the effects of temperature, aromatase inhibitor and their interaction on metamorphosis, locomotion, and sex ratios. A G-test and contingency table were used to analyze the metamorphosis rate of tadpoles and the survival rate of froglets after feeding for 90 days. A G-test was also used to analyze sex ratios in different treatment groups. Results Metamorphosis time and body size (snout–vent length, body mass and condition factor) were significantly different between the two temperature treatments. Metamorphosis time was longer and body size was increased at 29 °C compared to those at 34 °C. Letrozole concentration and the temperature × letrozole interaction did not affect these variables. The jumping distance of froglets following metamorphosis was positively associated with the condition factor; when controlling for condition factor, jumping distance was not affected by temperature, letrozole concentration and their interaction. Temperature and letrozole concentration also did not affect metamorphosis and survival rate. Sex ratio of the control group (0 mg/g letrozole) was 1:1 at 29 °C, but there were more males at 34 °C. The sex ratios of H. rugulosus treated with letrozole at 29 °C and 34 °C were significantly biased toward males, and male ratio increased as letrozole concentration increased. Furthermore, more males were produced at 34 °C than at 29 °C at each letrozole concentration.

Competitive Motherhood from a Comparative Perspective

2016 ◽  
Author(s):  
Katherine A. Valentine ◽  
Norman P. Li ◽  
Jose C. Yong
Keyword(s):  
Reproductive Success ◽  
Sex Ratio ◽  
Nonhuman Primates ◽  
Resource Competition ◽  
Sex Ratios ◽  
Comparative Perspective ◽  
Future Directions ◽  
Competition Hypothesis ◽  
Resource Enhancement

Mothers play an important role in helping their children achieve maximal reproductive success. We explore how mothers across species manipulate birth sex ratios favoring the sex that will be best suited to their environments and how maternal competition affects offspring reproductive success in nonhuman mammals as well as humans. The Trivers-Willard hypothesis, resource competition hypothesis, resource enhancement hypothesis, and maternal dominance hypothesis are considered with respect to maternal birth sex ratio manipulation. Next, the primate literature is reviewed as inspiration for hypotheses on maternal competition for positive offspring outcomes. Nonhuman primates as well as humans are argued to compete for status, breeding opportunities, and allomothers (i.e., caregivers apart from the mother), and these factors have an impact on their reproductive success. Status is passed on from mother to offspring, amplifying the effects of competition for status. Future directions are delineated to fill in gaps in the existing literature.

Mating system, mate choice and parental care in a bark beetle

2017 ◽  
Vol 107 (5) ◽  
pp. 611-619 ◽  
Author(s):  
O. Baruch ◽  
Z. Mendel ◽  
I. Scharf ◽  
A. R Harari
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Mate Choice ◽  
Parental Care ◽  
Mating System ◽  
Assortative Mating ◽  
Bark Beetle ◽  
Biparental Care ◽  
Male Body ◽  
Male Body Size

AbstractThe cypress bark beetle,Phloeosinus armatus, is a common element of the dying cypress tree system in East-Mediterranean countries. Adult beetles congregate for breeding on this ephemeral resource. We studied three traits that characterize this beetle's sexual behavior and linked them to its reproductive success: mating system, mate choice, and parental care. We found that the females are the ‘pioneering sex’, excavating the mating chamber. The average female is slightly larger than the male, and female and male body size is correlated, demonstrating size-assortative mating. The time it takes for a male to enter the mating chamber is positively correlated with female size and negatively correlated with its own size, which is perhaps responsible for this assortative mating. Males remain in the gallery during the period of oviposition, gradually leaving soon after the eggs hatch. The number of eggs laid and tunnel length are positively correlated with male body size. Finally, in the presence of both parents, more eggs are laid than when the female alone is present, demonstrating the important contribution of biparental care for reproductive success. We suggest that the interaction between a monogamous mating system, assortative mating, and biparental care contributes to reproductive success.

Variation in mating pattern in a population of the Andean frog Hyla labialis

2001 ◽  
Vol 22 (2) ◽  
pp. 199-207 ◽  
Author(s):  
Horst Lüddecke
Keyword(s):  
Body Size ◽  
Mate Choice ◽  
Female Mate Choice ◽  
Male Competition ◽  
The Body ◽  
Size Difference ◽  
Mating Pattern ◽  
Colombian Andes ◽  
Reproductive Females ◽  
Breeding Seasons

AbstractUnmated frogs and mated pairs from a population of individually marked Hyla labialis were captured, measured and released over four consecutive years in a highland valley of the Colombian Andes. Across eight prolonged breeding seasons, three times more males than females were captured. On average, females were significantly larger than males. Although the largest reproductive males were larger than the smallest reproductive females, amplexing males were always smaller than the females they clasped. Larger males had no mating advantage, because the body size distribution of males was the same for mated and unmated males, and the average snout-vent length of mated males was similar to that of unmated males. There was no indication of larger males taking over clasped females during male-male competition, because there was no size difference between males clasping gravid, spawning and spent females. Significantly size-assortative matings occurred on days when male availability per female was moderately high, but not when it was low, suggesting that female mate choice is relatively more important than male-male competition in shaping mating pattern.

Sex ratio variation in gastrointestinal nematodes of Svalbard reindeer; density dependence and implications for estimates of species composition

Parasitology ◽  
2004 ◽  
Vol 130 (1) ◽  
pp. 99-107 ◽  
Author(s):  
A. STIEN ◽  
M. DALLIMER ◽  
R. J. IRVINE ◽  
O. HALVORSEN ◽  
R. LANGVATN ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Species Composition ◽  
Density Dependence ◽  
Sex Ratios ◽  
Gastrointestinal Nematodes ◽  
Late Winter ◽  
Adult Males ◽  
Svalbard Reindeer ◽  
Ratio Variation ◽  
Adult Sex Ratio

Estimates of the intensity and abundance of species provide essential data for ecological, evolutionary and epidemiological studies of gastrointestinal nematode communities. These estimates are typically derived from the species composition of adult males when only males have readily scorable species-specific morphological traits. Such estimation assumes that all species in the community have the same adult sex ratio. We evaluated this assumption for the trichostrongyle nematodes Ostertagia gruehneri and Marshallagia marshalli in infracommunities in Svalbard reindeer by identifying to species adult females using a polymerase chain reaction assay. The proportion of males was found to be slightly higher in O. gruehneri than in M. marshalli. Evidence for seasonal variation and density dependence in the adult sex ratio was only found for O. gruehneri. Possible demographic mechanisms for such sex ratio variation are discussed, and stochastic models that generate density-dependent sex ratios proposed. Sex ratio variation caused substantial bias in some male-based estimates of intensity of infection, while substantial and consistent bias in estimates of abundances was only evident in late winter samples. Our results suggest that estimating sex ratios can be particularly important in individual host level studies of nematode species of low abundance.

scholarly journals Estimating adult sex ratios in nature

2017 ◽  
Vol 372 (1729) ◽  
pp. 20160313 ◽  
Author(s):  
Sergio Ancona ◽  
Francisco V. Dénes ◽  
Oliver Krüger ◽  
Tamás Székely ◽  
Steven R. Beissinger
Keyword(s):  
Sex Differences ◽  
Sex Ratio ◽  
Evolutionary Biology ◽  
Adult Population ◽  
Sex Ratios ◽  
Estimation Methods ◽  
Spatial And Temporal Variation ◽  
Animal Populations ◽  
Adult Sex Ratio ◽  
Males And Females

Adult sex ratio (ASR, the proportion of males in the adult population) is a central concept in population and evolutionary biology, and is also emerging as a major factor influencing mate choice, pair bonding and parental cooperation in both human and non-human societies. However, estimating ASR is fraught with difficulties stemming from the effects of spatial and temporal variation in the numbers of males and females, and detection/capture probabilities that differ between the sexes. Here, we critically evaluate methods for estimating ASR in wild animal populations, reviewing how recent statistical advances can be applied to handle some of these challenges. We review methods that directly account for detection differences between the sexes using counts of unmarked individuals (observed, trapped or killed) and counts of marked individuals using mark–recapture models. We review a third class of methods that do not directly sample the number of males and females, but instead estimate the sex ratio indirectly using relationships that emerge from demographic measures, such as survival, age structure, reproduction and assumed dynamics. We recommend that detection-based methods be used for estimating ASR in most situations, and point out that studies are needed that compare different ASR estimation methods and control for sex differences in dispersal. This article is part of the themed issue ‘Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies’.

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