Maternal Condition, Reproductive Investment, and Offspring Sex Ratio in Captive Red Junglefowl (Gallus gallus)

Abstract Maternal condition can affect reproductive investment in one or more ways. Captive female Red Junglefowl (Gallus gallus) that were heavier, controlling for tarsus length, produced larger eggs and initiated laying earlier, but did not produce more eggs per clutch. Maternal mass was also a positive predictor of offspring mass. That appears to result from the strong positive relationships between egg size and offspring mass. When the relationship between egg size and offspring mass was statistically controlled, maternal mass no longer predicted offspring mass. Mothers in better condition produced male-biased broods, as predicted when offspring condition depends on maternal condition and when male reproductive success is more dependent than female reproductive success on condition.

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No Evidence for Adaptive Differential Sex Allocation in Red Junglefowl (Gallus Gallus)

The Auk ◽

10.1093/auk/122.4.1161 ◽

2005 ◽

Vol 122 (4) ◽

pp. 1161-1168

Author(s):

Timothy H. Parker

Keyword(s):

Sex Ratio ◽

Brood Size ◽

Sex Allocation ◽

Gallus Gallus ◽

Ratio Analysis ◽

Maternal Condition ◽

Sperm Donor ◽

Sex Ratio Bias ◽

Red Junglefowl ◽

Ratio Data

Abstract In many situations, selection should favor females that bias the sex ratio of their offspring. Two commonly examined factors potentially influencing off- spring sex ratio are paternal ornamentation and maternal condition. Male junglefowl with larger combs are attractive to females. I housed female Red Junglefowl (Gallus gallus) with sterile male consorts and artificially inseminated them with sperm from other males that the females never saw. I found no relationship between either the comb size of the consort or the comb size of the sperm donor and the sex ratio of the offspring. I previously reported a significant sex ratio bias related to maternal mass in Red Junglefowl. However, that analysis was based on sex ratio data not weighted for brood size and assuming a normal distribution. Here, I show that this effect disappears when I conduct a more appropriate analysis weighting sex ratio according to brood size and accounting for the binomial error distribution. I also failed to find evidence that male chicks hatch from larger eggs than female chicks. These results suggest that Red Junglefowl females may not bias the sex ratio of their brood in response to either their own condition or the attractiveness of the males with whom they copulate. Furthermore, these results demonstrate the importance of choosing the correct methods of sex ratio analysis. Falta de Evidencia de Asignación Adaptativa Diferencial entre Sexos en Gallus gallus

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Maternal condition and previous reproduction interact to affect offspring sex in a wild mammal

Biology Letters ◽

10.1098/rsbl.2016.0510 ◽

2016 ◽

Vol 12 (8) ◽

pp. 20160510 ◽

Cited By ~ 8

Author(s):

Mathieu Douhard ◽

Marco Festa-Bianchet ◽

Fanie Pelletier

Keyword(s):

Sex Ratio ◽

Empirical Studies ◽

Good Condition ◽

Ovis Canadensis ◽

Maternal Condition ◽

Paternal Effects ◽

Offspring Sex Ratio ◽

Fitness Consequences ◽

Offspring Sex ◽

Dimorphic Species

Trivers and Willard proposed that offspring sex ratio should vary with maternal condition when condition, meant as maternal capacity to care, has different fitness consequences for sons and daughters. In polygynous and dimorphic species, mothers in good condition should preferentially produce sons, whereas mothers in poor condition should produce more daughters. Despite its logical appeal, support for this hypothesis has been inconsistent. Sex-ratio variation may be influenced by additional factors, such as environmental conditions and previous reproduction, which are often ignored in empirical studies. We analysed 39 years of data on bighorn sheep ( Ovis canadensis ) that fit all the assumptions of the Trivers–Willard hypothesis. Production of sons increased with maternal condition only for mothers that weaned a son the previous year. This relationship likely reflects a mother's ability to bear the higher reproductive costs of sons. The interaction between maternal condition and previous weaning success on the probability of producing a son was independent of the positive effect of paternal reproductive success. Maternal and paternal effects accounted for similar proportions of the variance in offspring sex. Maternal reproductive history should be considered in addition to current condition in studies of sex allocation.

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Differential sex allocation in sand lizards: bright males induce daughter production in a species with heteromorphic sex chromosomes

Biology Letters ◽

10.1098/rsbl.2005.0327 ◽

2005 ◽

Vol 1 (3) ◽

pp. 378-380 ◽

Cited By ~ 19

Author(s):

Mats Olsson ◽

Erik Wapstra ◽

Tobias Uller

Keyword(s):

Sex Ratio ◽

Reproductive Investment ◽

Experimental Manipulation ◽

Polymorphism Analysis ◽

Offspring Sex Ratio ◽

Heteromorphic Sex Chromosomes ◽

Offspring Sex ◽

In The Wild ◽

Lacerta Agilis ◽

Energetic Expenditure

In sand lizards ( Lacerta agilis ), males with more and brighter nuptial coloration also have more DNA fragments visualized in restriction fragment length polymorphism analysis of their major histocompatibility complex class I loci (and, hence, are probably more heterozygous at these loci). Such males produce more viable offspring, with a particularly strong viability effect on daughters. This suggests that females should adjust both their reproductive investment and offspring sex ratio in relation to male coloration (i.e. differential allocation). Our results show that experimental manipulation of partner coloration in the wild results in significantly higher maternal effort and a 10% higher proportion of daughters than sons. This supports the hypothesis that females increase their maternal energetic expenditure and adjust their offspring sex ratio in response to high-quality partners. However, it also suggests that this has probably evolved through natural selection for increased offspring viability (primarily through production of daughters), rather than through increased mate attraction (e.g. sexy sons).

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