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Bolund, Elisabeth
Publications (5 of 5) Show all publications
Griffin, R. M., Hayward, A. D., Bolund, E., Maklakov, A. A. & Lummaa, V. (2018). Sex differences in adult mortality rate mediated by early-life environmental conditions. Ecology Letters, 21(2), 235-242
Open this publication in new window or tab >>Sex differences in adult mortality rate mediated by early-life environmental conditions
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2018 (English)In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, no 2, p. 235-242Article in journal (Refereed) Published
Abstract [en]

Variation in sex differences is affected by both genetic and environmental variation, with rapid change in sex differences being more likely due to environmental change. One case of rapid change in sex differences is human lifespan, which has become increasingly female-biased in recent centuries. Long-term consequences of variation in the early-life environment may, in part, explain such variation in sex differences, but whether the early-life environment mediates sex differences in life-history traits is poorly understood in animals. Combining longitudinal data on 60 cohorts of pre-industrial Finns with environmental data, we show that the early-life environment is associated with sex differences in adult mortality and expected lifespan. Specifically, low infant survival rates and high rye yields (an important food source) in early-life are associated with female-bias in adult lifespan. These results support the hypothesis that environmental change has the potential to affect sex differences in life-history traits in natural populations of long-lived mammals.

Place, publisher, year, edition, pages
WILEY, 2018
Keywords
Development, environmental variation, humans, life-history, sexual dimorphism
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-349833 (URN)10.1111/ele.12888 (DOI)000425823900009 ()29210148 (PubMedID)
Funder
Swedish Research CouncilEU, European Research Council
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-05-07Bibliographically approved
Bolund, E. & Lummaa, V. (2017). The effects of resource availability and the demographic transition on the genetic correlation between number of children and grandchildren in humans. Heredity, 118(2), 186-192
Open this publication in new window or tab >>The effects of resource availability and the demographic transition on the genetic correlation between number of children and grandchildren in humans
2017 (English)In: Heredity, ISSN 0018-067X, E-ISSN 1365-2540, Vol. 118, no 2, p. 186-192Article in journal (Refereed) Published
Abstract [en]

Studies of evolutionary change require an estimate of fitness, and lifetime reproductive success is widely used for this purpose. However, many species face a trade-off between the number and quality of offspring and in such cases number of grandoffspring may better represent the genetic contribution to future generations. Here, we apply quantitative genetic methods to a genealogical data set on humans from Finland to address how the genetic correlation between number of children and grandchildren is influenced by the severity of the trade-off between offspring quality and quantity, as estimated by different levels of resource access among individuals in the population. Further, we compare the genetic correlation before and after the demographic transition to low mortality and fertility rates. The genetic correlation was consistently high (0.79-0.92) with the strongest correlations occurring in individuals with higher access to resources and before the demographic transition, and a tendency for lower correlations in resource poor individuals and after the transition. These results indicate that number of grandoffspring is a slightly better predictor of long-term genetic fitness than number of offspring in a human population across a range of environmental conditions, and more generally, that patterns of resource availability need to be taken into account when estimating genetic covariances with fitness.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2017
National Category
Evolutionary Biology Genetics
Identifiers
urn:nbn:se:uu:diva-319646 (URN)10.1038/hdy.2016.81 (DOI)000394361600009 ()27624115 (PubMedID)
Funder
Wenner-Gren Foundations
Available from: 2017-04-07 Created: 2017-04-07 Last updated: 2017-11-29Bibliographically approved
Bolund, E., Lummaa, V., Smith, K. R., Hanson, H. A. & Maklakov, A. A. (2016). Reduced costs of reproduction in females mediate a shift from a male-biased to a female-biased lifespan in humans. Scientific Reports, 6, Article ID 24672.
Open this publication in new window or tab >>Reduced costs of reproduction in females mediate a shift from a male-biased to a female-biased lifespan in humans
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2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 24672Article in journal (Refereed) Published
Abstract [en]

The causes underlying sex differences in lifespan are strongly debated. While females commonly outlive males in humans, this is generally less pronounced in societies before the demographic transition to low mortality and fertility rates. Life-history theory suggests that reduced reproduction should benefit female lifespan when females pay higher costs of reproduction than males. Using unique longitudinal demographic records on 140,600 reproducing individuals from the Utah Population Database, we demonstrate a shift from male-biased to female-biased adult lifespans in individuals born before versus during the demographic transition. Only women paid a cost of reproduction in terms of shortened post-reproductive lifespan at high parities. Therefore, as fertility decreased over time, female lifespan increased, while male lifespan remained largely stable, supporting the theory that differential costs of reproduction in the two sexes result in the shifting patterns of sex differences in lifespan across human populations. Further, our results have important implications for demographic forecasts in human populations and advance our understanding of lifespan evolution.

National Category
Obstetrics, Gynecology and Reproductive Medicine Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:uu:diva-296854 (URN)10.1038/srep24672 (DOI)000374254700002 ()27087670 (PubMedID)
Funder
Wenner-Gren FoundationsEU, European Research CouncilSwedish Research CouncilNIH (National Institute of Health), AG022095
Available from: 2016-06-20 Created: 2016-06-20 Last updated: 2017-11-28Bibliographically approved
Bruckner, T. A., Helle, S., Bolund, E. & Lummaa, V. (2015). Culled males, infant mortality and reproductive success in a pre-industrial Finnish population. Proceedings of the Royal Society of London. Biological Sciences, 282(1799)
Open this publication in new window or tab >>Culled males, infant mortality and reproductive success in a pre-industrial Finnish population
2015 (English)In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1799Article in journal (Refereed) Published
Abstract [en]

Theoretical and empirical literature asserts that the sex ratio (i.e. M/F) at birth gauges the strength of selection in utero and cohort quality of males that survive to birth. We report the first individual-level test in humans, using detailed life-history data, of the 'culled cohort' hypothesis that males born to low annual sex ratio cohorts show lower than expected infant mortality and greater than expected lifetime reproductive success. We applied time-series and structural equation methods to a unique multi-generational dataset of a natural fertility population in nineteenth century Finland. We find that, consistent with culled cohorts, a 1 s.d. decline in the annual cohort sex ratio precedes an 8% decrease in the risk of male infant mortality. Males born to lower cohort sex ratios also successfully raised 4% more offspring to reproductive age than did males born to higher cohort sex ratios. The offspring result, however, falls just outside conventional levels of statistical significance. In historical Finland, the cohort sex ratio gauges selection against males in utero and predicts male infant mortality. The reproductive success findings, however, provide weak support for an evolutionarily adaptive explanation of male culling in utero.

Keywords
culled cohorts, male frailty, sex ratio, lifetime reproductive success, infant mortality
National Category
Evolutionary Biology
Identifiers
urn:nbn:se:uu:diva-256555 (URN)10.1098/rspb.2014.0835 (DOI)000354866500001 ()25621334 (PubMedID)
Available from: 2015-06-24 Created: 2015-06-24 Last updated: 2017-12-04Bibliographically approved
Bolund, E., Hayward, A., Pettay, J. E. & Lummaa, V. (2015). Effects of the demographic transition on the genetic variances and covariances of human life-history traits. Evolution, 69(3), 747-755
Open this publication in new window or tab >>Effects of the demographic transition on the genetic variances and covariances of human life-history traits
2015 (English)In: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 69, no 3, p. 747-755Article in journal (Refereed) Published
Abstract [en]

The recent demographic transitions to lower mortality and fertility rates in most human societies have led to changes and even quick reversals in phenotypic selection pressures. This can only result in evolutionary change if the affected traits are heritable, but changes in environmental conditions may also lead to subsequent changes in the genetic variance and covariance (the G matrix) of traits. It currently remains unclear if there have been concomitant changes in the G matrix of life-history traits following the demographic transition. Using 300 years of genealogical data from Finland, we found that four key life-history traits were heritable both before and after the demographic transition. The estimated heritabilities allow a quantifiable genetic response to selection during both time periods, thus facilitating continued evolutionary change. Further, the G matrices remained largely stable but revealed a trend for an increased additive genetic variance and thus evolutionary potential of the population after the transition. Our results demonstrate the validity of predictions of evolutionary change in human populations even after the recent dramatic environmental change, and facilitate predictions of how our biology interacts with changing environments, with implications for global public health and demography.

Keywords
Genetic correlation, heritability, stability of G, variance-covariance matrix
National Category
Evolutionary Biology Ecology Genetics
Identifiers
urn:nbn:se:uu:diva-251830 (URN)10.1111/evo.12598 (DOI)000351446000015 ()25564932 (PubMedID)
Available from: 2015-04-27 Created: 2015-04-24 Last updated: 2017-12-04Bibliographically approved
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