Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders
In contrast to theoretical predictions of even adult sex ratios, males are dominating in many bird populations. Such bias among adults may be critical to population growth and viability. Nevertheless, demographic mechanisms for biased adult sex ratios are still poorly understood. Here, we examined p...
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ftunivturku:oai:www.utupub.fi:10024/169018 2023-05-15T18:20:27+02:00 Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders Patrik Karell Markus Öst Andreas Lindén Mikael Kilpi Satu Ramula ekologia ja evoluutiobiologia, Ecology and Evolutionary Biology 2606402 2022-10-28T14:02:43Z https://www.utupub.fi/handle/10024/169018 en eng PUBLIC LIBRARY SCIENCE United States Yhdysvallat (USA) US 13 ARTN e0195415 10.1371/journal.pone.0195415 PLoS ONE 4 https://www.utupub.fi/handle/10024/169018 URN:NBN:fi-fe2021042719100 1932-6203 2022 ftunivturku 2022-11-03T00:02:06Z In contrast to theoretical predictions of even adult sex ratios, males are dominating in many bird populations. Such bias among adults may be critical to population growth and viability. Nevertheless, demographic mechanisms for biased adult sex ratios are still poorly understood. Here, we examined potential demographic mechanisms for the recent dramatic shift from a slight female bias among adult eider ducks (Somateria mollissima) to a male bias (about 65% males) in the Baltic Sea, where the species is currently declining. We analysed a nine-year dataset on offspring sex ratio at hatching based on molecularly sexed ducklings of individually known mothers. Moreover, using demographic data from long-term individual-based capture-recapture records, we investigated how sex-specific survival at different ages after fledgling can modify the adult sex ratio. More specifically, we constructed a stochastic two-sex matrix population model and simulated scenarios of different survival probabilities for males and females. We found that sex ratio at hatching was slightly female-biased (52.8%) and therefore unlikely to explain the observed male bias among adult birds. Our stochastic simulations with higher survival for males than for females revealed that despite a slight female bias at hatching, study populations shifted to a male-biased adult sex ratio (> 60% males) in a few decades. This shift was driven by prime reproductive-age individuals(>5-year-old), with sex-specific survival of younger age classes playing a minor role. Hence, different age classes contributed disproportion ally to population dynamics. We argue that an alternative explanation for the observed male dominance among adults sex-biased dispersal can be considered redundant and is unlikely, given the ecology of the species. The present study highlights the importance of considering population structure and age-specific vital rates when assessing population dynamics and management targets. Other/Unknown Material Somateria mollissima University of Turku: UTUPub |
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University of Turku: UTUPub |
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English |
description |
In contrast to theoretical predictions of even adult sex ratios, males are dominating in many bird populations. Such bias among adults may be critical to population growth and viability. Nevertheless, demographic mechanisms for biased adult sex ratios are still poorly understood. Here, we examined potential demographic mechanisms for the recent dramatic shift from a slight female bias among adult eider ducks (Somateria mollissima) to a male bias (about 65% males) in the Baltic Sea, where the species is currently declining. We analysed a nine-year dataset on offspring sex ratio at hatching based on molecularly sexed ducklings of individually known mothers. Moreover, using demographic data from long-term individual-based capture-recapture records, we investigated how sex-specific survival at different ages after fledgling can modify the adult sex ratio. More specifically, we constructed a stochastic two-sex matrix population model and simulated scenarios of different survival probabilities for males and females. We found that sex ratio at hatching was slightly female-biased (52.8%) and therefore unlikely to explain the observed male bias among adult birds. Our stochastic simulations with higher survival for males than for females revealed that despite a slight female bias at hatching, study populations shifted to a male-biased adult sex ratio (> 60% males) in a few decades. This shift was driven by prime reproductive-age individuals(>5-year-old), with sex-specific survival of younger age classes playing a minor role. Hence, different age classes contributed disproportion ally to population dynamics. We argue that an alternative explanation for the observed male dominance among adults sex-biased dispersal can be considered redundant and is unlikely, given the ecology of the species. The present study highlights the importance of considering population structure and age-specific vital rates when assessing population dynamics and management targets. |
author2 |
ekologia ja evoluutiobiologia, Ecology and Evolutionary Biology 2606402 |
author |
Patrik Karell Markus Öst Andreas Lindén Mikael Kilpi Satu Ramula |
spellingShingle |
Patrik Karell Markus Öst Andreas Lindén Mikael Kilpi Satu Ramula Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
author_facet |
Patrik Karell Markus Öst Andreas Lindén Mikael Kilpi Satu Ramula |
author_sort |
Patrik Karell |
title |
Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
title_short |
Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
title_full |
Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
title_fullStr |
Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
title_full_unstemmed |
Increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
title_sort |
increased male bias in eider ducks can be explained by sex-specific survival of prime-age breeders |
publisher |
PUBLIC LIBRARY SCIENCE |
publishDate |
2022 |
url |
https://www.utupub.fi/handle/10024/169018 |
genre |
Somateria mollissima |
genre_facet |
Somateria mollissima |
op_relation |
13 ARTN e0195415 10.1371/journal.pone.0195415 PLoS ONE 4 https://www.utupub.fi/handle/10024/169018 URN:NBN:fi-fe2021042719100 1932-6203 |
_version_ |
1766197979677458432 |