The survival of the Alpine finch is threatened by the reduced exchange of individuals (and therefore genes) between the different reproductive areas, which are increasingly distant from each other due to habitat fragmentation caused by climate change and human activities.
This is demonstrated by an innovative study based on genomics, published in the Journal of Biogeography by the Museum of Natural Sciences of Alto Adige, the State University of Milan, the University of Oulu (Finland), the Science Museum of Trento (Muse) and Eurac Research.
Genetic analyzes conducted on dozens of Alpine finches from Trentino-Alto Adige and Lombardy reveal that the exchange of individuals (i.e. dispersal) is affected by the distance between the breeding areas, with a strong decrease starting from 20-30 kilometers .
In this sector of the Alps, many individuals therefore remain to reproduce in the area where they were born: the low propensity to disperse thus limits gene flow and population connectivity.
Furthermore, high levels of inbreeding were observed: 20% of the sampled individuals were in fact born to parents related to each other at least at the level of first cousins, if not even more closely.
This indicates that dispersal in the population is already insufficient to guarantee mating opportunities with unrelated individuals.
“These high levels of inbreeding are particularly alarming, because they can lead to the expression of deleterious recessive mutations, decreasing the probability of survival of individuals and their reproductive success", comments Francesco Ceresa, ornithologist at the Museum of Natural Sciences of Alto Adige and first author of the study. “The combined effects of habitat reduction, poor dispersal, and inbreeding effects can easily lead to local extinctions, which reduces overall population size and the effective extent of the breeding range.
In fact, local extinctions or strong declines of this species have already been found in some Alpine sectors."
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