Egg load is a cue for offspring sex ratio adjustment in a fig‐pollinating wasp with male‐eggs‐first sex allocation

2019 ◽  
Vol 33 (3) ◽  
pp. 366-376 ◽  
Author(s):  
Xiao‐Wei Zhang ◽  
Derek W. Dunn ◽  
Rui Wu Wang
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Egg Load ◽  
Offspring Sex Ratio ◽  
First Sex ◽  
Offspring Sex ◽  
Sex Ratio Adjustment

scholarly journals Sperm sex ratio adjustment in a mammal: perceived male competition leads to elevated proportions of female-producing sperm

2020 ◽  
Vol 16 (6) ◽  
pp. 20190929
Author(s):  
Renée C. Firman ◽  
Jamie N. Tedeschi ◽  
Francisco Garcia-Gonzalez
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Female Offspring ◽  
Male Competition ◽  
Offspring Sex ◽  
Sex Ratio Adjustment ◽  
Adaptive Adjustment ◽  
Male House

Mammal sex allocation research has focused almost exclusively on maternal traits, but it is now apparent that fathers can also influence offspring sex ratios. Parents that produce female offspring under conditions of intense male–male competition can benefit with greater assurance of maximized grand-parentage. Adaptive adjustment in the sperm sex ratio, for example with an increase in the production of X-chromosome bearing sperm (CBS), is one potential paternal mechanism for achieving female-biased sex ratios. Here, we tested this mechanistic hypothesis by varying the risk of male–male competition that male house mice perceived during development, and quantifying sperm sex ratios at sexual maturity. Our analyses revealed that males exposed to a competitive ‘risk’ produced lower proportions of Y-CBS compared to males that matured under ‘no risk’ of competition. We also explored whether testosterone production was linked to sperm sex ratio variation, but found no evidence to support this. We discuss our findings in relation to the adaptive value of sperm sex ratio adjustments and the role of steroid hormones in socially induced sex allocation.

Host size-dependent sex allocation behaviour in a parasitoid: implications forCatolaccus grandis(Hymenoptera: Pteromalidae) mass rearing programmes

1998 ◽  
Vol 88 (1) ◽  
pp. 37-45 ◽  
Author(s):  
K.M. Heinz
Keyword(s):  
Biological Control ◽  
Sex Ratio ◽  
Sex Allocation ◽  
Sex Ratios ◽  
Boll Weevil ◽  
Mass Rearing ◽  
Host Size ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Control Programmes

AbstractAn often encountered problem associated with augmentative and inundative biological control programmes is the high cost of producing sufficient numbers of natural enemies necessary to suppress pest populations within the time constraints imposed by ephemeral agroecosystems. In many arrhenotokous parasitoids, overproduction of males in mass-rearing cultures inflates costs (per female) and thus limits the economic feasibility of these biological control programmes. Within the context of existing production technologies, experiments were conducted to determine if the sex ratio ofCatolaccus grandis(Burks), an ectoparasitoid of the boll weevilAnthonomous grandisBoheman, varied as a function of boll weevil larval size. Results from natural and manipulative experiments demonstrate the following behavioural characteristics associated with C.grandissex allocation behaviour: (i) femaleC. grandisoffspring are produced on large size hosts and male offspring are produced on small hosts; (ii) whether a host is considered large or small depends upon the overall distribution of host sizes encountered by a female parasitoid; and (iii) female parasitoids exhibit a greater rate of increase in body size with host size than do male parasitoids. The observed patterns cannot be explained by sex-specific mortality of immature parasitoids developing on the different host size categories. In subsequent experiments, laboratory cultures ofC. grandisexposed daily to successively larger sizes ofA. grandislarvae produced successively greater female biased offspring sex ratios, cultures exposed daily to successively smaller sizes of host larvae produced successively greater male biased offspring sex ratios, and cultures exposed daily to equivalent host size distributions over time maintained a uniform offspring sex ratio. By increasing the average size ofA. grandislarval hosts exposed toC. grandisby 2.5 mg per day in mass rearing cultures, the percentage of male progeny can be reduced from 33% to 23% over a period of four consecutive exposure days.

scholarly journals Maternal stress to partner quality is linked to adaptive offspring sex ratio adjustment

2011 ◽  
Vol 22 (4) ◽  
pp. 717-722 ◽  
Author(s):  
Sarah R. Pryke ◽  
Lee A. Rollins ◽  
William A. Buttemer ◽  
Simon C. Griffith
Keyword(s):  
Sex Ratio ◽  
Maternal Stress ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Sex Ratio Adjustment

scholarly journals Breeding ecology and bias in offspring sex ratio in little grassbirds (Megalurus gramineus)

2003 ◽  
Vol 51 (5) ◽  
pp. 505 ◽  
Author(s):  
Rebecca R. McIntosh ◽  
Romke Kats ◽  
Mathew Berg ◽  
Jan Komdeur ◽  
Mark A. Elgar
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Salt Marshes ◽  
Sex Allocation ◽  
Breeding Ecology ◽  
Offspring Sex Ratio ◽  
Reed Beds ◽  
Primary Sex Ratio ◽  
Sex Ratio Bias ◽  
Offspring Sex

Little grassbirds (Megalurus gramineus) are small, sexually monomorphic passerines that live in reed beds, lignum swamps and salt marshes in southern Australia. The breeding biology and patterns of sex allocation of the little grassbird were investigated over a single breeding season. Our observations of this species in the Edithvale Wetland Reserve revealed a highly male-biased population sex ratio, with some breeding territories containing several additional males. Nevertheless, there was little compelling evidence that little grassbirds breed cooperatively. The growth rates of male and female nestlings were similar and, as predicted by theory, there was no overall primary sex ratio bias. However, the primary sex ratio was female-biased early in the breeding season and became increasingly male-biased later in the breeding season.

scholarly journals Sex allocation strategies in response to conspecifics’ offspring sex ratio in solitary parasitoids

2009 ◽  
Vol 21 (1) ◽  
pp. 107-112 ◽  
Author(s):  
Sébastien Lebreton ◽  
Claude Chevrier ◽  
Eric Darrouzet
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Allocation Strategies

scholarly journals Male spiders control offspring sex ratio through greater production of female-determining sperm

2018 ◽  
Vol 285 (1875) ◽  
pp. 20172887 ◽  
Author(s):  
Bram Vanthournout ◽  
Mette Marie Busck ◽  
Jesper Bechsgaard ◽  
Frederik Hendrickx ◽  
Andreas Schramm ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
Diploid Species ◽  
Underlying Mechanism ◽  
Mendelian Segregation ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Gamete Production ◽  
Paternal Control ◽  
Heterogametic Sex

Sex allocation theory predicts that when sons and daughters have different reproductive values, parents should adjust offspring sex ratio towards the sex with the higher fitness return. Haplo-diploid species directly control offspring sex ratio, but species with chromosomal sex determination (CSD) were presumed to be constrained by Mendelian segregation. There is now increasing evidence that CSD species can adjust sex ratio strategically, but the underlying mechanism is not well understood. One hypothesis states that adaptive control is more likely to evolve in the heterogametic sex through a bias in gamete production. We investigated this hypothesis in males as the heterogametic sex in two social spider species that consistently show adaptive female-biased sex ratio and in one subsocial species that is characterized by equal sex ratio. We quantified the production of male (0) and female (X) determining sperm cells using flow cytometry, and show that males of social species produce significantly more X-carrying sperm than 0-sperm, on average 70%. This is consistent with the production of more daughters. Males of the subsocial species produced a significantly lower bias of 54% X-carrying sperm. We also investigated whether inter-genomic conflict between hosts and their endosymbionts may explain female bias. Next generation sequencing showed that five common genera of bacterial endosymbionts known to affect sex ratio are largely absent, ruling out that endosymbiont bacteria bias sex ratio in social spiders. Our study provides evidence for paternal control over sex allocation through biased gamete production as a mechanism by which the heterogametic sex in CSD species adaptively adjust offspring sex ratio.

scholarly journals Transgenerational cues about local mate competition affect offspring sex ratios in the spider mite Tetranychus urticae

2017 ◽  
Author(s):  
Alison B. Duncan ◽  
Cassandra Marinosci ◽  
Céline Devaux ◽  
Sophie Lefèvre ◽  
Sara Magalhães ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Tetranychus Urticae ◽  
Sex Allocation ◽  
Spider Mite ◽  
Sex Ratios ◽  
Mate Competition ◽  
Maternal Environment ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Local Mate

ABSTRACTThis preprint has been reviewed and recommended by Peer Community In Evolutionary Biology (https://doi.org/10.24072/pci.evolbiol.100051). In structured populations, competition for mates between closely related males, termed Local Mate Competition (LMC), is expected to select for female-biased offspring sex ratios. However, the cues underlying sex allocation decisions remain poorly studied. Here, we test for several cues in the spider mite Tetranychus urticae, a species that was previously found to adjust the sex ratio of its offspring in response to the number of females within the local population, i.e. a patch. We here investigate whether the offspring sex ratio of T. urticae females changes in response to 1) the current number of females in the same patch, 2) the number of females in the patches of their mothers and 3) their relatedness to their mate. Single females on patches produced similar sex ratios to those of groups of 15 females; their mothers had been in identical conditions of panmixia. The offspring sex ratios of females mated with their brother did not differ from those of females mated with an unrelated male. Females however produced a more female-biased offspring sex ratio if their mothers were alone on a patch compared to 15 other females. Thus, maternal environment is used as a cue for the sex allocation of daughters. We discuss the conditions under which the maternal environment may be a reliable predictor of LMC experienced by grand-sons.

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