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Producing sons reduces lifetime reproductive success of subsequent offspring in pre-industrial Finns.

Rickard IJ, Russell AF, Lummaa V - Proc. Biol. Sci. (2007)

Bottom Line: Controlling for confounding factors such as socio-economic status and ecological conditions, we show that those offspring born after elder brothers have similar survival but lower LRS compared with those born after elder sisters.Our results demonstrate a maternal cost of reproduction manifested in reduced LRS of subsequent offspring.To our knowledge, this is the first time such a long-term intergenerational cost has been shown in a mammal species.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK. i.rickard@sheffield.ac.uk

ABSTRACT
Life-history theory states that reproductive events confer costs upon mothers. Many studies have shown that reproduction causes a decline in maternal condition, survival or success in subsequent reproductive events. However, little attention has been given to the prospect of reproductive costs being passed onto subsequent offspring, despite the fact that parental fitness is a function of the reproductive success of progeny. Here we use pedigree data from a pre-industrial human population to compare offspring life-history traits and lifetime reproductive success (LRS) according to the cost incurred by each individual's mother in the previous reproductive event. Because producing a son versus a daughter has been associated with greater maternal reproductive cost, we hypothesize that individuals born to mothers who previously produced sons will display compromised survival and/or LRS, when compared with those produced following daughters. Controlling for confounding factors such as socio-economic status and ecological conditions, we show that those offspring born after elder brothers have similar survival but lower LRS compared with those born after elder sisters. Our results demonstrate a maternal cost of reproduction manifested in reduced LRS of subsequent offspring. To our knowledge, this is the first time such a long-term intergenerational cost has been shown in a mammal species.

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(a) Lifetime fecundity (number of children produced) according to sex of elder sibling (mean±s.e.). (b) Offspring survival rate (proportion of offspring surviving to age 15) according to the sex of elder offspring (mean±s.e.). Values are adjusted means from the final model.
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fig3: (a) Lifetime fecundity (number of children produced) according to sex of elder sibling (mean±s.e.). (b) Offspring survival rate (proportion of offspring surviving to age 15) according to the sex of elder offspring (mean±s.e.). Values are adjusted means from the final model.

Mentions: Among those who survived to age 15 and were successfully followed until the end of potential reproductive life, the median lifetime fecundity was 4 and the maximum 13. Fecundity differed between parishes (Χ42=39.12, p<0.0001) and was higher for those in the rich and middle social classes than those in the poor class (Χ22=42.70, p<0.0001, adjusted means±s.e. 4.81±0.18, 4.66±0.21 and 2.45±0.28 for rich, middle class and poor, respectively). After controlling for these effects, we found that lifetime fecundity was significantly higher (12%) in those born after elder sisters than in those born after elder brothers (Χ12=5.06, p=0.025; figure 3a). Lifetime fecundity was not significantly associated with year of birth (Χ12=0.11, p=0.74), birth order (Χ12=0.00, p=0.96), family size (Χ12=1.22, p=0.27), previous birth interval (Χ12=0.82, p=0.37) or own sex (Χ12=0.10, p=0.75).


Producing sons reduces lifetime reproductive success of subsequent offspring in pre-industrial Finns.

Rickard IJ, Russell AF, Lummaa V - Proc. Biol. Sci. (2007)

(a) Lifetime fecundity (number of children produced) according to sex of elder sibling (mean±s.e.). (b) Offspring survival rate (proportion of offspring surviving to age 15) according to the sex of elder offspring (mean±s.e.). Values are adjusted means from the final model.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211518&req=5

fig3: (a) Lifetime fecundity (number of children produced) according to sex of elder sibling (mean±s.e.). (b) Offspring survival rate (proportion of offspring surviving to age 15) according to the sex of elder offspring (mean±s.e.). Values are adjusted means from the final model.
Mentions: Among those who survived to age 15 and were successfully followed until the end of potential reproductive life, the median lifetime fecundity was 4 and the maximum 13. Fecundity differed between parishes (Χ42=39.12, p<0.0001) and was higher for those in the rich and middle social classes than those in the poor class (Χ22=42.70, p<0.0001, adjusted means±s.e. 4.81±0.18, 4.66±0.21 and 2.45±0.28 for rich, middle class and poor, respectively). After controlling for these effects, we found that lifetime fecundity was significantly higher (12%) in those born after elder sisters than in those born after elder brothers (Χ12=5.06, p=0.025; figure 3a). Lifetime fecundity was not significantly associated with year of birth (Χ12=0.11, p=0.74), birth order (Χ12=0.00, p=0.96), family size (Χ12=1.22, p=0.27), previous birth interval (Χ12=0.82, p=0.37) or own sex (Χ12=0.10, p=0.75).

Bottom Line: Controlling for confounding factors such as socio-economic status and ecological conditions, we show that those offspring born after elder brothers have similar survival but lower LRS compared with those born after elder sisters.Our results demonstrate a maternal cost of reproduction manifested in reduced LRS of subsequent offspring.To our knowledge, this is the first time such a long-term intergenerational cost has been shown in a mammal species.

View Article: PubMed Central - PubMed

Affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK. i.rickard@sheffield.ac.uk

ABSTRACT
Life-history theory states that reproductive events confer costs upon mothers. Many studies have shown that reproduction causes a decline in maternal condition, survival or success in subsequent reproductive events. However, little attention has been given to the prospect of reproductive costs being passed onto subsequent offspring, despite the fact that parental fitness is a function of the reproductive success of progeny. Here we use pedigree data from a pre-industrial human population to compare offspring life-history traits and lifetime reproductive success (LRS) according to the cost incurred by each individual's mother in the previous reproductive event. Because producing a son versus a daughter has been associated with greater maternal reproductive cost, we hypothesize that individuals born to mothers who previously produced sons will display compromised survival and/or LRS, when compared with those produced following daughters. Controlling for confounding factors such as socio-economic status and ecological conditions, we show that those offspring born after elder brothers have similar survival but lower LRS compared with those born after elder sisters. Our results demonstrate a maternal cost of reproduction manifested in reduced LRS of subsequent offspring. To our knowledge, this is the first time such a long-term intergenerational cost has been shown in a mammal species.

Show MeSH