SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS
Human twinning rates are considered to either reflect the direct fitness effects of twinning in variable environments, or to be a maladaptive by-product of selection for other maternal reproductive traits (e.g., polyovulation). We used historical data (1710–1890) of Sami populations from Northern Sc...
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The Society for the Study of Evolution
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ftbioone:10.1554/03-307 2023-07-30T04:06:37+02:00 SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS Samuli Helle Virpi Lummaa Jukka Jokela Samuli Helle Virpi Lummaa Jukka Jokela world 2004-02-01 text/HTML https://doi.org/10.1554/03-307 en eng The Society for the Study of Evolution doi:10.1554/03-307 All rights reserved. https://doi.org/10.1554/03-307 Text 2004 ftbioone https://doi.org/10.1554/03-307 2023-07-09T09:26:55Z Human twinning rates are considered to either reflect the direct fitness effects of twinning in variable environments, or to be a maladaptive by-product of selection for other maternal reproductive traits (e.g., polyovulation). We used historical data (1710–1890) of Sami populations from Northern Scandinavia to contrast these alternative hypotheses. We found that women who produced twins started their reproduction younger, ceased it later, had higher lifetime fecundity, raised more offspring to adulthood, and had higher fitness (individual λ) than mothers of singletons in all populations studied. For example, an average of 1.2 offspring survived to adulthood from a twin delivery, irrespective of its sex ratio, whereas only 0.8 offspring survived to adulthood from a singleton delivery. Only if mothers started reproduction at very late age (>37 yr), or had a very long reproductive life span (>20 yr), was it more beneficial to produce only singletons. These findings suggest that twin deliveries among Sami could not be explained as a maladaptive by-product of selection for other maternal reproductive traits. In contrast, our results suggest that twinning was under natural selection, although the strength of selection was likely to have been context dependent. Text sami BioOne Online Journals Evolution 58 2 430 |
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English |
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Human twinning rates are considered to either reflect the direct fitness effects of twinning in variable environments, or to be a maladaptive by-product of selection for other maternal reproductive traits (e.g., polyovulation). We used historical data (1710–1890) of Sami populations from Northern Scandinavia to contrast these alternative hypotheses. We found that women who produced twins started their reproduction younger, ceased it later, had higher lifetime fecundity, raised more offspring to adulthood, and had higher fitness (individual λ) than mothers of singletons in all populations studied. For example, an average of 1.2 offspring survived to adulthood from a twin delivery, irrespective of its sex ratio, whereas only 0.8 offspring survived to adulthood from a singleton delivery. Only if mothers started reproduction at very late age (>37 yr), or had a very long reproductive life span (>20 yr), was it more beneficial to produce only singletons. These findings suggest that twin deliveries among Sami could not be explained as a maladaptive by-product of selection for other maternal reproductive traits. In contrast, our results suggest that twinning was under natural selection, although the strength of selection was likely to have been context dependent. |
author2 |
Samuli Helle Virpi Lummaa Jukka Jokela |
format |
Text |
author |
Samuli Helle Virpi Lummaa Jukka Jokela |
spellingShingle |
Samuli Helle Virpi Lummaa Jukka Jokela SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
author_facet |
Samuli Helle Virpi Lummaa Jukka Jokela |
author_sort |
Samuli Helle |
title |
SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
title_short |
SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
title_full |
SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
title_fullStr |
SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
title_full_unstemmed |
SELECTION FOR INCREASED BROOD SIZE IN HISTORICAL HUMAN POPULATIONS |
title_sort |
selection for increased brood size in historical human populations |
publisher |
The Society for the Study of Evolution |
publishDate |
2004 |
url |
https://doi.org/10.1554/03-307 |
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world |
genre |
sami |
genre_facet |
sami |
op_source |
https://doi.org/10.1554/03-307 |
op_relation |
doi:10.1554/03-307 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1554/03-307 |
container_title |
Evolution |
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58 |
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2 |
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430 |
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1772819339494293504 |