Does variation of sex ratio enhance reproductive success of offspring in tawny owls (<i>Strix aluco</i>)

Appleby, Bridget M.; Petty, S. J.; Blakey, Jeremy K.; Rainey, Paul B.; Macdonald, David W.

doi:10.1098/rspb.1997.0153

Cited by 129 publications

(133 citation statements)

References 28 publications

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“…Few studies have examined repeatability of brood sex ratio but the results suggest variation among species. Brood sex ratio was significantly repeatable between years in blue tits (Parus caeruleus; Griffith et al 2003), but not in great tits (Parus major; Oddie & Reim 2002) or tawny owls (Strix aluco; Appleby et al 1997). These maternal effects should be considered in future studies of brood sex ratios.…”

Section: Discussionmentioning

confidence: 95%

Maternal influences on brood sex ratios: an experimental study in tree swallows

2005

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When the reproductive value of sons and daughters differ, parents are expected to adjust the sex ratio of their offspring to produce more of the sex that provides greater fitness returns. The body condition of females or environmental factors, such as food abundance and mate quality, may influence these expected fitness returns. In a previous study of tree swallows (Tachycineta bicolor), we found that females produced more sons in their broods when they were in better body condition (mass corrected for size). We tested this relationship by experimentally clipping some flight feathers to reduce female body condition. As predicted, we found that females with clipped feathers had a lower proportion of sons in their broods and poorer body condition. However, female body condition alone was not a significant predictor of brood sex ratio in our experiment. We suggest that brood sex ratio is causally related to some other factor that covaries with body condition, most likely the foraging ability of females. The hypothesis that brood sex ratios are influenced by individual differences in female foraging ability is supported by a high repeatability of brood sex ratio for individual females. Thus, maternal effects may have a strong influence on the sex ratios of offspring.

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Section: Discussionmentioning

confidence: 95%

Maternal influences on brood sex ratios: an experimental study in tree swallows

2005

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“…(iii) Investigate whether the BSR is adjusted according to the identified factors, both in correlative and experimental studies. Currently, only a few studies have investigated whether sex ratio manipulation does lead to increased fitness, even though some studies have presented data suggesting this (Appleby et al 1997;Komdeur 1998). The long-term and inclusive fitness effects of the BSR are still unknown and experimental work in this area is urgently required (see also Komdeur & Pen 2002).…”

Section: How To Investigate Adaptive Bsr Manipulation In Relation To mentioning

confidence: 99%

Parental care and adaptive brood sex ratio manipulation in birds

Hasselquist

Kempenaers

2002

Phil. Trans. R. Soc. Lond. B

168

128

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Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against nonsignificant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex-differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.

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“…In this context, when resources are plentiful or high-quality, females are expected to produce more offspring of the sex that will gain the greatest benefit from increased investment or nutritional quality [1,15], and thus yield the highest return of fitness. Conversely, when conditions are harsh, females should produce offspring of the sex that suffers least from reduced environmental or parental condition [16,17].…”

Section: Introductionmentioning

confidence: 99%

Mothers adjust offspring sex to match the quality of the rearing environment

Pryke

Rollins

2012

Proc. R. Soc. B.

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Theory predicts that mothers should adjust offspring sex ratios when the expected fitness gains or rearing costs differ between sons and daughters. Recent empirical work has linked biased offspring sex ratios to environmental quality via changes in relative maternal condition. It is unclear, however, whether females can manipulate offspring sex ratios in response to environmental quality alone (i.e. independent of maternal condition). We used a balanced within-female experimental design (i.e. females bred on both low-and high-quality diets) to show that female parrot finches (Erythrura trichroa) manipulate primary offspring sex ratios to the quality of the rearing environment, and not to their own body condition and health. Individual females produced an unbiased sex ratio on high-quality diets, but over-produced sons in poor dietary conditions, even though they maintained similar condition between diet treatments. Despite the lack of sexual size dimorphism, such sex ratio adjustment is in line with predictions from sex allocation theory because nutritionally stressed foster sons were healthier, grew faster and were more likely to survive than daughters. These findings suggest that mothers may adaptively adjust offspring sex ratios to optimally match their offspring to the expected quality of the rearing environment.

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Does variation of sex ratio enhance reproductive success of offspring in tawny owls (Strix aluco)

Cited by 129 publications

References 28 publications

Maternal influences on brood sex ratios: an experimental study in tree swallows

Maternal influences on brood sex ratios: an experimental study in tree swallows

Parental care and adaptive brood sex ratio manipulation in birds

Mothers adjust offspring sex to match the quality of the rearing environment

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