Royal dynasties as human inbreeding laboratories: the Habsburgs |
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Authors: | F C Ceballos G álvarez |
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Institution: | 1.Department of Genetics, Faculty of Biology,
University of Santiago de Compostela, Santiago de Compostela, Spain |
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Abstract: | The European royal dynasties of the Early Modern Age provide a useful framework for human
inbreeding research. In this article, consanguineous marriage, inbreeding depression and
the purging of deleterious alleles within a consanguineous population are investigated in
the Habsburgs, a royal dynasty with a long history of consanguinity over generations.
Genealogical information from a number of historical sources was used to compute kinship
and inbreeding coefficients for the Habsburgs. The marriages contracted by the Habsburgs
from 1450 to 1750 presented an extremely high mean kinship (0.0628±0.009), which
was the result of the matrimonial policy conducted by the dynasty to establish political
alliances through marriage. A strong inbreeding depression for both infant and child
survival was detected in the progeny of 71 Habsburg marriages in the period
1450–1800. The inbreeding load for child survival experienced a pronounced decrease
from 3.98±0.87 in the period 1450–1600 to 0.93±0.62 in the period
1600–1800, but temporal changes in the inbreeding depression for infant survival
were not detected. Such a reduction of inbreeding depression for child survival in a
relatively small number of generations could be caused by elimination of deleterious
alleles of a large effect according with predictions from purging models. The differential
purging of the infant and child inbreeding loads suggest that the genetic basis of
inbreeding depression was probably very different for infant and child survival in the
Habsburg lineage. Our findings provide empirical support that human inbreeding depression
for some fitness components might be purged by selection within consanguineous
populations. |
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Keywords: | royal inbreeding Habsburg dynasty consanguineous marriage inbreeding depression purging of inbreeding depression |
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