Sexual size dimorphism and offspring vulnerability in birds

Kalmbach, Ellen; Benito, María Martínez

doi:10.1093/acprof:oso/9780199208784.003.0015

Cited by 35 publications

(34 citation statements)

References 707 publications

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“…females) [53]. Juvenile mortalities may be sex-specific for several reasons: male offspring-which are often larger than female offspring-may die more often than females if they are more sensitive to food shortage [23]; such costs of sexual selection for males have also been documented at the juvenile stage in primates [54].…”

Section: Discussionmentioning

confidence: 99%

“…First, biased ASR may emerge as a consequence of biased juvenile sex ratios. Sex ratios may already be biased at conception ( primary SR), or at birth or hatching (secondary SR), or male and female juveniles may die at different rates [17,[21][22][23]. Second, differential adult survival may bias ASR, because one sex may be predated more often than the other [24,25], or be more susceptible to parasites and pathogens [26].…”

Section: Introductionmentioning

confidence: 99%

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Sex-biased survival predicts adult sex ratio variation in wild birds

et al. 2014

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Adult sex ratio (ASR) is a central concept in population demography and breeding system evolution, and has implications for population viability and biodiversity conservation. ASR exhibits immense interspecific variation in wild populations, although the causes of this variation have remained elusive. Using phylogenetic analyses of 187 avian species from 59 families, we show that neither hatching sex ratios nor fledging sex ratios correlate with ASR. However, sex-biased adult mortality is a significant predictor of ASR, and this relationship is robust to 100 alternative phylogenetic hypotheses, and potential ecological and life-history confounds. A significant component of adult mortality bias is sexual selection acting on males, whereas increased reproductive output predicts higher mortality in females. These results provide the most comprehensive insights into ASR variation to date, and suggest that ASR is an outcome of selective processes operating differentially on adult males and females. Therefore, revealing the causes of ASR variation in wild populations is essential for understanding breeding systems and population dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sex-biased survival predicts adult sex ratio variation in wild birds

et al. 2014

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“…For example, previous studies have shown that sex-specific vulnerabilities during embryo and offspring development are not only related to sexual size dimorphism (i.e. larger sex has greater nutritional requirements [28,29]), but may also be influenced or exacerbated by sex-specific phenotypes (e.g. costs of testosterone in males [30,31]), clutch size [32] and genetic factors (e.g.…”

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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“…In bird species with sexual dimorphism, the two sexes often reach their fledging mass at the same age (Kalmbach & Benito 2007). For that, the smaller sex must grow at a faster rate than the larger sex, especially if the two sexes fledge at similar masses.…”

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confidence: 99%

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

Jordi

Arizaga

2016

Bird Study

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Capsule: Chick growth rates was sex-dependent in an Atlantic Yellow-legged Gull Larus michahellis population. Aims: To describe the growth rate of Yellow-legged Gull chicks and sex-associated variations, and obtain a discriminant function to sex them using morphological data. Methods: Fifty-two Yellow-legged Gull chicks from a colony in northern Iberia were measured for body mass, head and bill length, tarsus length and three other bill-length associated variables, from the hatching date up to the age of 36 days. Birds were sexed using DNA analysis. Results: Using logistic models, chick growth rates was observed to be similar between the sexes, while the asymptote was higher among males for the majority of the variables. Discriminant analyses showed that the variable head+bill was very reliable to predict the sex of >80% of chicks at an early developmental stage, and 100% of chicks if combined with tarsus length and two more bill-length associated variables at the age of 35 days. Conclusions: This is the first study using a discriminant analysis to sex Yellow-legged Gull chicks, and also the first to describe the growth function for the species. The growth rate varied between sexes because males showed higher asymptote values within the growth function. ARTICLE HISTORY

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Sexual size dimorphism and offspring vulnerability in birds

Cited by 35 publications

References 707 publications

Sex-biased survival predicts adult sex ratio variation in wild birds

Sex-biased survival predicts adult sex ratio variation in wild birds

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

Sex differences in growth rates of Yellow-legged Gull Larus michahellis chicks

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