Metal pollution does not bias offspring sex ratio in great tit (Parus major)

Eeva, Tapio; Sillanpää, Saila; Lehikoinen, Esa

doi:10.1007/s11356-012-0793-4

Cited by 3 publications

(3 citation statements)

References 51 publications

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“…This agrees with most experimental studies on species with large brood sizes (Oddie 2000;Potti et al 2002;Råberg et al 2005;Dubiec et al 2006;Nicolaus et al 2009, but see Tschirren et al 2003;Chin et al 2005) and a few observational studies (Dhondt 1970;Eeva et al 2012, but see Dietrich-Bischoff et al 2008). Our approach was observational and, therefore, a clear demonstration of the causal link was not possible.…”

Section: Discussionsupporting

confidence: 86%

Seasonal change in sexual differences in nestling size and survival: a framework to evaluate sex-dependent environmental sensitivity in the wild

2018

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Background: Sexual size dimorphism (SSD) occurs in a wide range of species in birds and other animals, but the magnitude of SSD often varies with environmental conditions. In general, in the developmental stages, the larger sex is more vulnerable to adverse environmental conditions because the larger sex requires more energy than the smaller sex. However, this may not hold true for birds with large brood sizes; the larger sex can acquire more food by suppressing the smaller sex. In addition, most previous studies have been experimental, such as by manipulating clutch size and ectoparasites, which may not reflect natural conditions. Methods:In the present study, we propose a general framework to assess sexual differences in environmental sensitivity in natural populations. Because environmental conditions change throughout the breeding season, seasonal changes of nestling SSD and sex ratio should reflect sexual differences in environmental sensitivity. We applied this approach to a large dataset (1555 nestlings over 5 years) of Japanese Tits (Parus minor). In this population, the male nestling is generally larger than the female (5% SSD in body weight). Results:We found that the magnitude of SSD (weight, tarsus, wing) and fledgling sex ratio increased both in the beginning and the end of the breeding season. Conclusion:Our study suggested that female nestlings are more valuable to poor environmental conditions in the relatively fecund species. This study underscores the importance of brood size on sexual differences in environmental stochasticity and our framework encourages comparative analysis among different bird species.

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Section: Discussionsupporting

confidence: 86%

Seasonal change in sexual differences in nestling size and survival: a framework to evaluate sex-dependent environmental sensitivity in the wild

2018

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“…So, the larger size and the presumably greater energy demand during development may make males more sensitive to adverse environmental effects than females (Swenson 1986, Jones et al 2009, Rosivall et al 2010, Bouvier et al 2016). On the other hand, some studies did not find an influence of adverse conditions on sex-specific survival in great tits, for instance by increased pollution levels (in 15 days old nestlings; Eeva et al 2012), by increased competition among siblings (Nicolaus et al 2009) or by handicapping the parents (Kubacka and Cichoń 2020). These latter results suggest that male-biased offspring mortality may not be explained exclusively by higher sensitivity of male offspring to adverse environmental conditions.…”

Section: Sex Ratio Of Dead Offspringmentioning

confidence: 95%

“…Although several studies examined how urbanization or metal pollution or other anthropogenic disturbances correlate with fledglings' sex ratio or mortality in great tits (e.g. Eeva et al 2012;Bouvier et al 2016;Corsini et al 2021), these studies did not provide data about the primary sex ratio or the sex of the dead offspring to infer sex differences in offspring mortality. One reason for the lack of data on sex-specific mortality may be the difficulty to detect unhatched eggs and dead nestlings in time to obtain tissue samples suitable for the molecular work (e.g.…”

Section: Introductionmentioning

confidence: 99%

Hard life for sons in the nest? Sex-dependent offspring mortality in great tits in relation to breeding habitat and age

Ágh

Dalvári

Szabó

et al. 2022

Preprint

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Sex-biased mortality can occur in birds during development, for example due to sexual differences in energy requirement and/or environmental sensitivity, or the effects of sex hormones or sex differences in expression of mutations linked to sex chromosomes. Urban habitats often provide poorer conditions for nestling development resulting in higher offspring mortality compared to natural habitats, which may accelerate sex differences in offspring mortality in cities. To test this hypothesis, we examined sex-specific offspring mortality in great tits (Parus major), using 660 samples of dead offspring collected in two urban and two forest sites between 2013-2019. Overall, the sex ratio of dead offspring was significantly male-biased (56.80%). When habitats and age groups were analysed separately, the sex ratio of dead offspring was significantly male-biased in urban habitat (57.60%) and in young nestlings (58.62%), and non-significantly in the forest habitat (56.58%) and in unhatched embryos (54.11%) or in old nestlings (54.55%). However, these estimates were associated with wide confidence intervals, thus sex ratios of dead offspring did not differ significantly among study sites and between age groups when these were analysed together. 70.30% of unhatched eggs was not fertilized, and their proportion did not differ between urban and forest habitats. These results suggest male-biased offspring mortality in great tits, and highlight the need of large datasets to detect subtle differences between habitats and developmental stages.

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Hard life for sons in the nest? Sex-dependent offspring mortality in Great Tits in urban and forest areas

Ágh,

Dalvári,

Szabó

et al. 2024

Avian Research

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Metal pollution does not bias offspring sex ratio in great tit (Parus major)

Abstract: We conclude that metal exposure at the levels found in our study area does not bias fledgling sex ratios in this species, but biased sex ratios may follow under natural or pollution-related resource limitation.

Cited by 3 publications

References 51 publications

Seasonal change in sexual differences in nestling size and survival: a framework to evaluate sex-dependent environmental sensitivity in the wild

Seasonal change in sexual differences in nestling size and survival: a framework to evaluate sex-dependent environmental sensitivity in the wild

Hard life for sons in the nest? Sex-dependent offspring mortality in great tits in relation to breeding habitat and age

Hard life for sons in the nest? Sex-dependent offspring mortality in Great Tits in urban and forest areas

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