Are there physiological constraints on maternal ability to adjust sex ratios in mammals?

Edwards, Amy M.; Cameron, Elissa Z.; Wapstra, Erik

doi:10.1111/jzo.12327

Cited by 18 publications

(16 citation statements)

References 108 publications

(149 reference statements)

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“…It has been noted that different mechanisms for sex allocation may operate simultaneously, either synergistically or antagonistically (Cameron et al ., ; Navarra, ; Edwards, Cameron & Wapstra, ). Although it remains for future research to determine whether conceptus survival in black howler monkeys is directly determined by sex differential reactivity to glucocorticoids (Kraemer, ), or to some other physiological mechanism involving glucocorticoid secretion — either directly or as a byproduct (Ryan et al ., ; Moore et al ., ) — our results indicate that glucocorticoids may be signaling environmental conditions to females around the time of conception.…”

Section: Discussionmentioning

confidence: 99%

Maternal glucocorticoid levels affect sex allocation in black howler monkeys

et al. 2017

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When sons and daughters impart different fitness benefits, mothers should bias investment according to offspring sex, in some cases modifying offspring sex ratios. Sex allocation in monotocous organisms is expected to be costlier than for polytocous species, as it imposes a greater loss of reproductive effort in terms of mating and fertilization. Here, we show that variation in glucocorticoid concentrations around the time of conception predicts infant sex in a monotocous anthropoid, the black howler monkey (Alouatta pigra), suggesting that sex allocation is linked to a hormonal mechanism that affects early embryonic development. Glucocorticoids signal environmental conditions, and in our study, their variation was positively related to factors affecting infant survival. These results offer insight into sex allocation strategies in monotocous organisms.

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Section: Discussionmentioning

confidence: 99%

Maternal glucocorticoid levels affect sex allocation in black howler monkeys

et al. 2017

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“…For example, one study revealed that one domestic bull produced 76% male embryos [107], but the attributes of this male were not reported, unfortunately. In addition, seminal fluid, which contains sugars such as glucose, may favor the fertilization and/or development of one offspring sex over the other [56]. In addition, seminal fluid, which contains sugars such as glucose, may favor the fertilization and/or development of one offspring sex over the other [56].…”

Section: Douhardmentioning

confidence: 99%

“…The overall inconsistency in the direction of sex-ratio biases with respect to physiological factors may be accounted for by the fact that these factors are inter-related and may act in opposition to each other [56] (Fig. 2).…”

Section: The Twh Now Relies On a Set Of Potential Physiological Mechamentioning

confidence: 99%

Offspring sex ratio in mammals and the Trivers‐Willard hypothesis: In pursuit of unambiguous evidence

Douhard

2017

BioEssays

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Can mammalian mothers adaptively control the sex of their offspring? The influential Trivers-Willard hypothesis (TWH) proposes that when maternal condition increases the fitness of sons more than that of daughters, the proportion of sons produced should increase with maternal condition. Studies of mammals, however, often fail to support this hypothesis. This article highlights recent advances, including studies on the assumptions of the TWH and physiological mechanisms for sex-ratio manipulation. Particular emphasis is placed on how factors such as paternal quality, maternal reproductive costs and environmental conditions experienced by mothers early in life can mask/alter the expected relationship between maternal condition and offspring sex ratio or lead to apparent support for the TWH. While there is growing evidence that sex ratio around conception may be maternally and paternally manipulated, a challenge for future studies on sex allocation is to integrate how multiple and potentially opposite selective pressures affect offspring sex ratio.

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“…High concentrations of hair testosterone in females, relative to levels in males, have also been recorded for wolves ( Canis lupus ; Bryan et al , 2014), Canada lynx ( Lynx canadensis ; Terwissen et al , 2014), and ring-tailed lemurs ( Lemur catta ; Tennenhouse et al , 2016). Although the significance of ‘high testosterone levels’ in female brown bears has not been explored, attention has been directed to the potential adaptive consequences of maternal testosterone levels on offspring behaviour (Dloniak et al , 2006) and sex ratios (Grant and Chamley, 2010; Edwards et al , 2016) in other mammals.…”

Section: Discussionmentioning

confidence: 99%