Inbreeding incidence on biological fitness in an isolated mediterranean population: La Alta Alpujarra Oriental (southeastern Spain).

The incidence of parental inbreeding on biological fitness was analysed in a sample of the Alpujarrenian population. Fitness was estimated as the fertility and offspring viability from conception to reproductive age. The analysed sample represents about 45% of the population from the Alta Alpujarra Oriental in southeastern Spain, and includes 847 families and 2916 pregnancies. The results showed slightly higher reproduction in consanguineous marriages, but the differences observed were not statistically significant. Higher pregnancy numbers are usually interpreted as stemming from greater immunological compatibility of the mother and foetus and may also reflect the significantly higher early foetal viability in this population. According to other authors, the great number of births observed in Alpujarrenian consanguineous marriages is, in part, a reproductive compensation for increased perinatal and neonatal mortality found as a possible negative result of homozygous combinations of deleterious alleles.