title: The effects of demographic transition on the opportunity for selection: changes during the last century in Italy.
abstract: The index of opportunity for selection proposed by Crow has been calculated for the Italian population during the last century. The evolution of its two components, the pre-reproductive mortality and the variance in fertility, has been also analysed and compared with similar data for the United States. The results clearly show the relevance of socio-economic changes to the evolution of selective patterns in our species; in particular the relative incidence of mortality and fertility to selection intensity: the total index has in fact been reduced by 75% during the last century, the relative amount due to fertility increasing from 57 to 89%. The probable different relevance of genetic factors in the two components has also been discussed.
mesh_terms: D003710:Demography; D005260:Female; D005298:Fertility; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D007558:Italy; D009026:Mortality; D012641:Selection, Genetic; D014481:United States