Should males come first? The relationship between offspring hatching order and sex in the black-headed gull Larus ridibundus

Ležalová, Radka; Tkadlec, Emil; Oborník, Miroslav; Šimek, J.; Honza, Marcel

doi:10.1111/j.2005.0908-8857.03466.x

Cited by 16 publications

(22 citation statements)

References 42 publications

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“…Falk and Møller ('90) also suggested that in large clutches of the peregrine falcon the last laid eggs should be expected to have thinner shells because of decreased levels of calcium available in the female body. In other bird species, eggshell thickness and egg size or egg volume also decrease with laying order irrespective of the sex of the embryo (Reynolds, 2001;Lezalova et al, 2005;Lislevand et al, 2005). In contrast, egg size and eggshell thickness appear to increase with female age in penguins (Massaro et al, 2002;Massaro and Davis, 2004).…”

Section: Laying Sequencementioning

confidence: 73%

Determinants of eggshell strength in endangered raptors

et al. 2009

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We compared eggshell strength in a group of falcon taxa including the peregrine falcon (Falco peregrinus peregrinus), the red shaheen falcon (F. peregrinus babylonicus), the saker falcon (F. cherrug), the gyr falcon (F. rusticolus) and some interspecific and intraspecific hybrids. Our results showed that smaller falcons (<1,000 g) of the peregrine group have eggshells that are significantly softer (x=13.3 N) and thinner (x=0.26 mm) (n=107 eggs) than larger falcons (>1,000 g) of the gyr-saker group (x=20.8 N and 0.39 mm, respectively, n=81 eggs). We found a significant positive correlation between egg hardness and eggshell thickness. Linear mixed models showed that clutches from heavier females consisted of larger and harder eggs with thicker shells and thicker egg membranes. Eggs produced by older females and eggs laid later in the laying sequence were relatively smaller and softer and had relatively thin egg membranes and eggshells. Individual females, irrespective of their age, contributed significantly to the observed variation in egg strength. Egg size and hardness of hybrid eggs were similar to that of the pure species suggesting that hybridization does not affect eggshell hardness or thickness. Our study provides quantitative evidence of several factors, other than levels of contamination, which may affect eggshell thickness and hardness in falcons.

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Section: Laying Sequencementioning

confidence: 73%

Determinants of eggshell strength in endangered raptors

et al. 2009

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“…; Carranza ; Ležalová et al . ; but see Cichoń, Dubiec & Stoczkom ; Johnson et al . ; Bowers et al .…”

Section: Discussionmentioning

confidence: 99%

Persistent sex‐by‐environment effects on offspring fitness and sex‐ratio adjustment in a wild bird population

Bowers

Thompson

Sakaluk

2014

Journal of Animal Ecology

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Summary A major component of sex-allocation theory, the Trivers-Willard Model (TWM), posits that sons and daughters are differentially affected by variation in the rearing environment. In many species, the amount of parental care received is expected to have differing effects on the fitness of males and females. When this occurs, the TWM predicts that selection should favour adjustment of the offspring sex ratio in relation to the expected fitness return from offspring. However, evidence for sex-by-environment effects is mixed and little is known about the adaptive significance of producing either sex. Here, we test whether offspring sex ratios vary according to predictions of the TWM in the house wren (Troglodytes aedon, Vieillot). We also test the assumption of a sex-by-environment effect on offspring using two experiments, one in which we manipulated age-differences among nestlings within broods, and another in which we held nestling age constant but manipulated brood size. As predicted, females with high investment ability over-produced sons relative to those with lower ability. Males were also over-produced early within breeding seasons. In our experiments, the body mass of sons was more strongly affected by the sibling-competitive environment and resource availability than that of daughters: males grew heavier than females when reared in good conditions but were lighter than females when in poor conditions. Parents rearing broods with 1:1 sex ratios were more productive than parents rearing broods biased more strongly towards sons or daughters, suggesting that selection favours the production of mixed-sex broods. However, differences in the condition of offspring as neonates persisted to adulthood, and their reproductive success as adults varied with the body mass of sons, but not daughters, prior to independence from parental care. Thus, selection should favour slight but predictable variations in the sex ratio in relation to the quality of offspring that parents are able to produce. Offspring sex interacts with the neonatal environment to influence offspring fitness, thus favouring sex-ratio adjustment by parents. However, increased sensitivity of males to environmental conditions, such as sibling rivalry and resource availability, reduces the fitness returns from highly male-biased broods.

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“…They could help explain why mothers often produce more offspring of the less vulnerable sex towards the end of the laying sequence, especially under unfavourable conditions (e.g. Nager et al 1999;Ležalová et al 2005). However, the mechanism(s) underlying these differences between the sexes remain to be established.…”

Section: Post-hatching Performancementioning

confidence: 99%

Sex-specific costs of hatching last: an experimental study on herring gulls (Larus argentatus)

Bogdanova

Nager

2008

Behav Ecol Sociobiol

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An organism's pattern of development can have important long-term fitness effects. In species where the sexes differ in size or other phenotypic traits, they may also have different optimal developmental rates. This influences both parental sex allocation strategies and susceptibility of the sexes to early developmental conditions. However, sex differences in developmental rate and vulnerability to environment during the embryonic period are not well understood. In birds, sibling competition and hatching asynchrony may select for accelerated embryonic development of the last offspring in order to reduce their competitive disadvantage after hatching. They may advance their hatching in response to vocal stimuli by the older siblings. It is, however, unclear whether this flexibility in developmental rates is sex specific. In this study, we experimentally manipulated between-embryo contact and tested whether this affected the pre-natal developmental rate and post-hatching performance of male and female offspring from last-laid eggs in the herring gull. Post-hatching performance was measured both in competitive and noncompetitive situations. Among young incubated in isolation, males hatched faster than females, but both sexes fledged in similar, relatively good condition. Among young incubated with normal between-embryo contact, hatching time did not differ between sexes, but males fledged in poorer condition than females, regardless of whether they were reared singly or in a brood. These results suggest that male and female offspring differ in their ability to mitigate the costs of hatching asynchrony.

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Should males come first? The relationship between offspring hatching order and sex in the black-headed gull Larus ridibundus

Cited by 16 publications

References 42 publications

Determinants of eggshell strength in endangered raptors

Determinants of eggshell strength in endangered raptors

Persistent sex‐by‐environment effects on offspring fitness and sex‐ratio adjustment in a wild bird population

Sex-specific costs of hatching last: an experimental study on herring gulls (Larus argentatus)

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