Find research datasets worth reusing
Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.
35
datasets available to search
ShareScore release 0.9.0
Dataset results
35 results for “offspring sex ratio”
Male biased sex ratio in the offspring of roe deer
<p>The file "metafor_roe_sex.csv" was used for the meta-analysis regarding the sex ratio of roe deer juveniles. It contains the columns: </p> <p>Author (author(s) of the publication, Country (country were the study was publised), Location (specific location, in case that the data set contains several different locations the term "divers" is used), Year (year(s) were the sex of roe deer offspring were documented), Pub-Year (Year of publication) , N (number of offspring), N_female (number of female offspring), Sex ratio (primary - P or secondary - S sex ratio), Habitat conditions (F - free ranging, I - Island conditions, C - captive), Proportion female (proportion of female juveniles), Low_95 (lower boundary for the proportion of females using an exact binomial test with a 95% confidence interval), High_95 (upper boundary for the proportion of females using an exact binomial test with a 95% confidence interval), d (effect size), d_se (standard error of the effect size), North (Latitude), East (Longitude)</p> <p>The file "sex_bw.csv" contains information about roe deer juveniles tacked in Baden-Württemberg. The columns read as: Year (year were the juvenile was tacked), sex (the sex of the juvenile, m- male; f- female), and Hasl (elevation in m)</p> <p>The file "temp_data_comma_sep.csv" contains the montly mean values for temperature (Temp) and precipitation (NDS) for the months January, February, March, ..., December for the German federal state Baden-Württemberg (Source German Weather Service).</p> <p>All data sets were used for analysis presented in: Evidence for a male-biased sex ratio in the offspring of a large herbivore: the role of environmental conditions in the sex ratio variation.</p> <p> </p> <p> </p>
Data for: Five decades of data yield no support for adaptive biasing of offspring sex ratio in wild baboons (Papio cynocephalus)
<p>Over the past 50 years, a wealth of testable, often conflicting, hypotheses has been generated about the evolution of offspring sex ratio manipulation by mothers. Several of these hypotheses have received support in studies of invertebrates and some vertebrate taxa. However, their success in explaining sex ratios in mammalian taxa, and especially in primates, has been mixed. Here, we assess the predictions of four different hypotheses about the evolution of biased offspring sex ratios in the well-studied baboons of the Amboseli basin in Kenya: the Trivers-Willard, female rank enhancement, local resource competition, and local resource enhancement hypotheses. Using the largest sample size ever analyzed in a primate population (n = 1372 offspring), we test the predictions of each hypothesis. Overall, we find no support for adaptive biasing of sex ratios. Offspring sex is not consistently related to maternal dominance rank or biased towards the dispersing sex, nor it is predicted by group size, population growth rates, or their interaction with maternal rank. Because our sample size confers power to detect even subtle biases in sex ratio, including modulation by environmental heterogeneity, these results suggest that adaptive biasing of offspring sex does not occur in this population.</p>
Data for: Five decades of data yield no support for adaptive biasing of offspring sex ratio in wild baboons (Papio cynocephalus)
Open the record for dataset details and reuse information.
Adult sex-ratio bias does not lead to detectable adaptive offspring sex allocation via nest-site choice in a turtle with temperature-dependent sex determination
Open the record for dataset details and reuse information.
Data from: A seasonal shift in offspring sex ratio of the brood parasitic Brown-headed Cowbird (Molothrus ater)
<p>Avian obligate brood parasites do not provide parental care for their eggs and young, and may therefore serve as a strong model system to test predictions of evolutionary sex-allocation theories, independent of parental modulation of primary sex ratios. However, none of the handful of previous studies examining offspring sex ratio in brood parasitic birds have revealed a bias from parity at the level of the female parasite, the host species, or temporal scale(s). This is also surprising, because in at least one brood parasite, the Brown-headed Cowbird (Molothrus ater), adult sex ratios are consistently and heavily male-biased. Here we used a large database of embryonic and nestling cowbirds' genetic sex ratios collected from nests of a single host species, the Prothonotary Warbler (Protonotaria citrea) to assess potential overall, temporal, and individual patterns of bias. Contrary to previous findings, we documented an increase in the calculated male sex ratios later in the breeding season. There was no effect of whether embryos or nestlings were sampled, implying a lack of host parental effect on shifting the primary-to-secondary sex ratios of brood parasitic offspring. Future work should explore the sex-specific survival and recruitment pattern of fledgling cowbirds raised by this and other host species to reconcile theoretical and empirical predictions and patterns.</p>
Boreal Owl Offspring Sex Ratio
<p>The dataset is associated with the paper titled “<strong>Fledgling Sex Ratio Is Determined by Egg Loss, Hatching Order, Nestling Mortality, and Inter‐Annual Food Fluctuations for Boreal Owls, </strong><em>Aegolius funereus</em>”, published in <em>Ecology and Evolution</em> (2025). The XLS file contains three sheets, each corresponding to one of the models described in the paper, along with an additional sheet providing information about the data.</p>
Variance in offspring sex ratio and maternal allocation in a highly invasive mammal
<p>Skewed sex ratios at birth are widely reported in wild populations, however the extent to which parents are able to modulate the sex ratio of offspring to maximize their own fitness remains unclear. This is particularly true for highly polytocous species as maximizing fitness may include trade-offs between sex ratio and the size and number of offspring in litters. In such cases, it may be adaptive for mothers to adjust both the number of offspring per litter and offspring sex to maximize individual fitness. Investigating maternal sex allocation in wild pigs (<em>Sus scrofa</em>) under stochastic environmental conditions, we predicted that, under favorable conditions, high quality mothers (larger, older) would produce male-biased litters and invest more in producing larger litters with more males. We also predicted sex ratio would vary relative to litter size, with a male-bias among smaller litters. We found evidence that increasing wild boar ancestry, maternal age and condition, and resource availability may weakly contribute to male-biased sex ratio, however, unknown factors not measured in this study are assumed to be more influential. High quality mothers allocated more resources in litter production, but this relationship was driven by adjustment of litter size, not sex ratio. There was no relationship between sex ratio and litter size. Collectively, our results emphasized that adjustment of litter size appeared to be the primary reproductive characteristic manipulated in wild pigs to increase fitness rather than adjustment of offspring sex ratio.</p>
Dietary fat supplements influence weight gain and egg production but not offspring sex ratios in Japanese quail
<p>Sex ratio theory suggests that females should bias offspring sex ratios based on maternal condition and the availability of critical food resources. Work in birds indicates that females do, indeed, bias sex ratios according to maternal condition and food quality and quantity. Yet it is unknown whether these sex ratio skews occur due to fluctuations in particular micro- or macro-nutrients, caloric content overall, or even the perception of food availability. We hypothesized that dietary fats may drive biases in offspring sex ratios, because measures of maternal condition often reflect fat reserves, and fats are critical for the process of egg-laying in birds. To test this, we provided breeding Japanese quail, a species that biases sex ratios in response to maternal condition, with either a control breeding diet or a diet supplemented with two oils (safflower oil and flaxseed oil). These oils were chosen for their high omega-3 and omega-6 fatty acid content as well as their importance in mammalian sex allocation. We then measured influences of these diets on the sex ratio of offspring, the change in maternal weight, and the laying rates of female quail. The dietary oil supplements increased weight gains in quail but decreased the number of eggs laid during the experiment. There was no influence of the oil supplements on offspring sex ratios. This indicates that fat may not be a macro-nutrient involved in the process of sex ratio adjustment in quail.</p>
Offspring sex ratio is affected by pre-breeding rainfall and hatching order in a cooperative breeding bird
<p><span>Selection may favour sex ratio adjustment when the fitness benefits of producing male or female offspring vary. In birds, sex ratio bias at hatching has been particularly well-studied in cooperative breeding species, primarily in helper-at-the-nest systems wherein young remain with their parents and help raise subsequent broods. In these systems, breeding females are expected to skew offspring sex ratio in favour of the helping sex if sufficient resources exist. In communal laying systems multiple group members breed and raise the young and offspring dispersal varies, making it difficult to predict whether and how breeders should skew offspring sex ratio. We tested for sex ratio bias in smooth-billed anis (<em>Crotophaga ani</em>), a communal laying cuckoo with low within-group relatedness, high offspring dispersal, and high annual turnover in group membership. One male performs nocturnal incubation and sires more offspring, suggesting these males may have higher reproductive variance and thus that it may be beneficial for his mate to produce more male offspring. We hypothesized that pre-breeding rainfall influences food availability and thus offspring sex ratio, predicting that breeding females skew production towards the more beneficial sex (i.e., males) in high food years, consistent with the Trivers-Willard hypothesis. Females may also adjust sex ratio across the hatching order, so we predicted a male-bias in first hatched chicks in larger broods that should experience greater competition. Contrary to our first prediction, more male chicks hatched when pre-breeding rainfall was lower. In partial support of our second prediction, marginally more first hatched chicks were male in larger broods. Based on these results, we propose the nestling competition hypothesis and predict that when nestling competition is high (i.e., in poor years and in large joint broods), mothers should produce more of the more competitive sex. </span></p>
Data from: A seasonal shift in offspring sex ratio of the brood parasitic Brown-headed Cowbird (Molothrus ater)
Open the record for dataset details and reuse information.
Offspring sex ratio is affected by pre-breeding rainfall and hatching order in a cooperative breeding bird
Open the record for dataset details and reuse information.
Variance in offspring sex ratio and maternal allocation in a highly invasive mammal
Open the record for dataset details and reuse information.
Female biased offspring sex ratios of eastern wild turkeys across the southeastern United States
Open the record for dataset details and reuse information.
Dietary fat supplements influence weight gain and egg production but not offspring sex ratios in Japanese quail
Open the record for dataset details and reuse information.
Offspring sex-ratios are stable across the life-course in Drosophila simulans
Within populations, adult sex ratios influence population growth and extinction risk, mating behaviors and parental care. Additionally, sex ratio adjustment can have pronounced effects on individual fitness. Accordingly, it is important that we understand how often, and why, offspring sex ratios deviate from parity. In Drosophila melanogaster, females appear to improve their fitness by producing fewer sons when paired with older males. However, facultative sex ratio adjustment in D. melanogaster is controversial, and our understanding of how sex ratio skew affects fitness is hampered by pronounced sexual conflict in this species. Additionally, it is unclear if maternal age or quality interact with paternal age to influence offspring sex ratios. Here, we test whether offspring sex ratios vary as a function of maternal quality, and maternal and paternal age in Drosophila simulans, a sister species of D. melanogaster that lacks overt sexual conflict. We find that offspring sex ratios are slightly male biased overall, but constant across the female life-course, and independent of female quality, or paternal age. To really understand if, how and when females skew offspring sex ratios, we need studies linking offspring sex ratios to male and female phenotypes that are predicted to shift optimal investment in sons and daughters.
Data from: Cross-fostering eggs reveals that female collared flycatchers adjust clutch sex ratios according to parental ability to invest in offspring
Across animal taxa, reproductive success is generally more variable and more strongly dependent upon body condition for males than for females; in such cases, parents able to produce offspring in above-average condition are predicted to produce sons, whereas parents unable to produce offspring in good condition should produce daughters. We tested this hypothesis in the collared flycatcher (Ficedula albicollis) by cross-fostering eggs among nests and using the condition of foster young that parents raised to fledging as a functional measure of their ability to produce fit offspring. As predicted, females raising heavier-than-average foster fledglings with their social mate initially produced male-biased primary sex ratios, whereas those raising lighter-than-average foster fledglings produced female-biased primary sex ratios. Females also produced male-biased clutches when mated to males with large secondary sexual characters (wing patches), and tended to produce male-biased clutches earlier within breeding seasons relative to females breeding later. However, females did not adjust the sex of individuals within their clutches; sex was distributed randomly with respect to egg size, laying order, and paternity. Future research investigating the proximate mechanisms linking ecological contexts and the quality of offspring parents are able to produce with primary sex-ratio variation could provide fundamental insight into the evolution of context-dependent sex-ratio adjustment.
Data from: Protoporphyrin-based eggshell pigmentation is associated with female plumage colouration and predicts offspring sex ratio in the barn swallow
Inter- and intraspecific variation in eggshell colouration has long fascinated evolutionary biologists. Among species, such variation may accomplish different functions, the most obvious of which is camouflage and background matching. Within species, it has been proposed that inter-female variation in eggshell pigmentation patterns can reflect egg, maternal or paternal traits and hence may provide cues to conspecifics about egg, maternal or paternal phenotypic quality. However, the relationship between protoporphyrin-based eggshell pigmentation and egg or maternal/paternal traits appears to be highly variable among species. We investigated patterns of intraspecific variation in Eurasian barn swallow (Hirundo r. rustica) protoporphyrin-based eggshell pigmentation, and analysed its association with egg and clutch characteristics, maternal/paternal phenotypic traits and parental feeding effort. Eggshell pigmentation pattern significantly varied between breeding colonies, was significantly repeatable in clutches laid by the same females in different years (intraclass correlation coefficient ranging between 0.56 and 0.63), but it was not significantly associated with egg traits, such as position in the laying sequence, egg mass, yolk testosterone concentration and antioxidant capacity. It was weakly or non-significantly associated with female and male traits (sexual ornaments), but females laying darker (higher pigment intensity) first clutches had higher hatching success, suggesting that eggshell pigment intensity may predict fitness. Nevertheless, males did not significantly modulate their parental nestling feeding effort accordingly. In addition, females with darker breast plumage colouration (a melanin-based trait related to fitness) laid highly protoporphyrin-covered eggs, suggesting the presence of a previously unappreciated link between protoporphyrin biosynthesis and plumage melanisation. Moreover, the proportion of male offspring increased in clutches originating from highly protoporphyrin-covered eggs, suggesting that parents could acquire visual cues about their future brood sex composition before egg hatching. Our results support the idea that intraspecific signalling via eggshell pigmentation is a species-specific rather than a general feature of avian taxa.
Data from: Sons do not take advantage of a head start: parity in herring gull offspring sex ratios despite greater initial investment in males
Skewed adult sex ratios sometimes occur in populations of free-living animals yet the proximate mechanisms, timing of sex-biases, and the selective agents contributing to skew remain a source of debate with contradictory evidence from different systems. We investigated potential mechanisms contributing to sex biases in a population of herring gulls with an apparent female skew in the adult population. Theory predicts that skewed adult sex ratios will adaptively lead to skewed offspring sex ratios to restore balance in the effective breeding population. Parents may also adaptively bias offspring sex ratios to increase their own fitness in response to environmental factors. Therefore, we expected to detect skewed sex ratios either at hatching or at fledging as parents invest differentially in offspring of different sexes. We sampled complete clutches (n = 336 chicks) at hatching to quantify potential skews in sex ratios by position in the hatch order, time of season, year, and nesting context (nest density), finding no departure from equal sex ratios at hatching related to any of these factors. Further, we sampled 258 chicks at near-fledging to investigate potential sex biases in survival at the chick stage. Again, no biases in sex ratios were recorded. Male offspring were favored in this population via greater maternal investment in eggs carrying male embryos and greater parental provisioning of male offspring which reached greater sizes by fledging. Despite the advantages realized by male offspring, females were equally as likely to fledge as males. Thus, biased adult sex ratios apparently arise in the post-fledging and pre-recruitment stage in our population.
Data from: Is biasing offspring sex ratio adaptive? a test of Fisher's principle across multiple generations of a wild mammal in a fluctuating environment
Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1:1 due to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have a higher number of grandoffspring. In a wild population of North American red squirrels (Tamiasciurus hudsonicus) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1:1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring by the time of their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.
Density dependence of clutch size and offspring sex ratio in starling colonies
<p><span>Optimal life-history theory predicts that individuals should adjust both the number and the sex of their offspring to maximize fitness in response to environmental and social factors such as breeding density. While reductions in optimal clutch size are well-studied in birds, the evidence for sex ratio adjustments is still equivocal and, so far, we lack a thorough understanding of how these strategies interact to maximize fitness. Here, we investigate how breeding density simultaneously affects brood sex ratio and clutch size in a sexually dimorphic and polygynous bird. We tested the prediction that mothers breeding at a higher density lay smaller clutches and overproduce daughters, the sex with less variable fitness returns and that disperses further away from their natal territory. We distributed nest boxes at either a high (HD) or a low density (LD) and monitored clutch sizes and sex ratios during five years in a wild breeding colony of spotless starlings. While mothers breeding in HD nests produced more daughters than those breeding in LD nests, the density dependence of clutch size varied among years, with a tendency to lay smaller clutches in HD nests. Our results suggest that mothers consistently adjust offspring sex ratio in response to breeding density, whereas adjustments in clutch size varied in a more complex way. These results support the role of sex allocation strategies in response to density and show that further theoretical and empirical research is required to understand the interaction between clutch size and sex ratio adjustments in animals.</span></p>
ScienceDex guides
Understand access before you commit
These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.