A father effect explains sex-ratio bias

Malo, Aurelio F.; Martínez‐Pastor, Felipe; García‐González, Francisco; Garde, José Julián; Ballou, Jonathan D.; Lacy, Robert C.

doi:10.1098/rspb.2017.1159

Cited by 33 publications

(51 citation statements)

References 51 publications

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“…In contrast to gestation length and covering success, we found that secondary sex ratio had a negligible maternal heritable component (0.005) with a high standard error, indicating that genetic variation in the mare has no influence on the sex of the foal. However, paternal heritability estimates revealed an extremely small but Other studies in mammals have also found evidence of male-driven sex ratio bias [33,34]. However, in contrast to these studies, we found no association between the inbreeding level of the sire and offspring sex ratio [33,34].…”

Section: Discussioncontrasting

confidence: 99%

“…However, paternal heritability estimates revealed an extremely small but Other studies in mammals have also found evidence of male-driven sex ratio bias [33,34]. However, in contrast to these studies, we found no association between the inbreeding level of the sire and offspring sex ratio [33,34]. It is postulated that higher quality, less inbred fathers produce more male offspring [35].…”

Section: Discussioncontrasting

confidence: 97%

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The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

et al. 2020

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Background: Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares provided by three Australian stud farms. Inbreeding was estimated using the pedigree of each individual dating back to the foundation of the breed in the eighteenth century. Results: While both gestation length and foaling rate were heritable, no measurable effect of inbreeding on either trait was found. However, we did find that the genetic value for both traits had decreased within recent generations. A number of environmental factors also had significant effects on foaling rate and gestation length. Secondary sex ratio had only an extremely small paternal heritable effect and was not susceptible to environmental influences. Conclusions: In contrast to racing performance, inbreeding had no measurable effect on foaling rate or gestation length in Australian Thoroughbred horses. This could be because the level of inbreeding in the population examined is not high enough to show a discernible effect on reproductive traits. Populations that experience higher levels of inbreeding due to use of artificial reproductive technologies or extremely small population sizes may show a more pronounced reduction in natural foaling rate or gestation length. It is also possible that the intensive management techniques used in the Thoroughbred population masks any negative effects of inbreeding. The decrease in the genetic value of foaling rate is likely to be because horses with unfavourable genetic potential have not yet been selected out of the population. The change in genetic value of gestation length may be due to selective breeding favouring horses with shorter pregnancies. We also found that prioritising the mating of older mares, and avoiding out of season mating could lead to an increased breeding success.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussioncontrasting

confidence: 97%

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

et al. 2020

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“…While the upstream transcriptional regulators Slx and Sly are specific to the Palaearctic radiation of mouse species, their mode of action appears to involve interaction with Ssty, which is present more widely in rodents and has become independently amplified in rat, together with its X-linked homologue Sstx [13,68,69]. Together with data indicating the presence of paternally-mediated sex ratio skewing in an even more distantly related rodent species, Peromyscus [70], and the presence of sequences related to Ssty in the genomes of Ellobius species [71], this suggests that the genomic conflict may be much longer-standing.…”

Section: Discussionmentioning

confidence: 99%

Differential sperm motility mediates the sex ratio drive shaping mouse sex chromosome evolution

Rathje

Johnson

Drage

et al. 2019

Preprint

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The search for morphological or physiological differences between X-and Y-bearing mammalian sperm has provoked controversy for decades. Many potential differences have been proposed, but none validated, while accumulating understanding of syncytial sperm development has cast doubt on whether such differences are possible even in principle. We present the first ever mammalian experimental model to trace a direct link from a measurable physiological difference between X-and Y-bearing sperm to the resulting skewed sex ratio. We show that in mice with deletions on chromosome Yq, birth sex ratio distortion is due to a relatively greater motility of X-bearing sperm, and not to any aspect of sperm/egg interaction. Moreover, the morphological distortion caused by Yq deletion is more severe in Y-bearing sperm, providing a potential hydrodynamic basis for the altered motility.This reinforces a growing body of work indicating that sperm haploid selection is an important and underappreciated evolutionary force.We thank the animal handling staff at

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“…In mammals, research has focused almost entirely on mothers, partly due to the assumption that the male contribution is under meiotic control and partly due to the differential cost of reproduction with mothers investing more in their offspring than fathers. However, studies investigating the possibility of paternal adaptive sex allocation are increasing and may explain some of the reported inconsistencies in offspring SR (e.g., Edwards & Cameron, ; Malo et al, ; Vanthournout et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Changes in sperm sex ratios (sperm SR) are likely to influence offspring SR but seminal fluids likely also play a vital role through cryptic male choice (Edwards & Cameron, ). Technological advances allow for a fast, cheap, and accurate analysis of sperm SR, which have now been recorded across a several taxa (e.g., Edwards & Cameron, ; Malo et al, ; Vanthournout et al, ). The mechanistic drivers of sperm SR biases remain understudied, but coital rate, environmental contaminants, and age are predicted to play a large role (Edwards & Cameron, ).…”

Section: Introductionmentioning

confidence: 99%

Sexual conflict in action: An antagonistic relationship between maternal and paternal sex allocation in the tammar wallaby, Notamacropus eugenii

Edwards

Cameron

Deakin

et al. 2019

Ecology and Evolution

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Sex ratio biases are often inconsistent, both among and within species and populations. While some of these inconsistencies may be due to experimental design, much of the variation remains inexplicable. Recent research suggests that an exclusive focus on mothers may account for some of the inconsistency, with an increasing number of studies showing variation in sperm sex ratios and seminal fluids. Using fluorescent in‐situ hybridization, we show a significant population‐level Y‐chromosome bias in the spermatozoa of wild tammar wallabies, but with significant intraindividual variation between males. We also show a population‐level birth sex ratio trend in the same direction toward male offspring, but a weaning sex ratio that is significantly female‐biased, indicating that males are disproportionately lost during lactation. We hypothesize that sexual conflict between parents may cause mothers to adjust offspring sex ratios after birth, through abandonment of male pouch young and reactivation of diapaused embryos. Further research is required in a captive, controlled setting to understand what is driving and mechanistically controlling sperm sex ratio and offspring sex ratio biases and to understand the sexually antagonistic relationship between mothers and fathers over offspring sex. These results extend beyond sex allocation, as they question studies of population processes that assume equal input of sex chromosomes from fathers, and will also assist with future reproduction studies for management and conservation of marsupials.

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A father effect explains sex-ratio bias

Cited by 33 publications

References 51 publications

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

Differential sperm motility mediates the sex ratio drive shaping mouse sex chromosome evolution

Sexual conflict in action: An antagonistic relationship between maternal and paternal sex allocation in the tammar wallaby, Notamacropus eugenii

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