Ricerc@Sapienza

Hybridization, the interbreeding of individuals from genetically distinct populations, has been
considered until recently a relatively rare event across animal species. However, it is with the
development of molecular techniques that hybrids have been increasingly detected, suggesting
hybridization may be a more widespread phenomenon than originally thought. Hybrids are not
necessarily less fit and, under given circumstances, they may also bear more successful adaptive traits
with respect to their parental populations. Hybrids can also re-integrate with parental populations by
backcrossing, leading to various levels of introgression. Whereas natural hybridization is considered a
positive evolutionary force and a source of evolutionary novelty, conservation-wise hybridization
caused by human impacts (anthropogenic hybridization, AH) may threaten the genetic integrity of
many wild plant and animal taxa. AH has been recently recognized as an increasing threat for
biodiversity worldwide due to human induced changes in species abundance and distribution, removal
of reproductive barriers, and introduction of non-native and domestic species. Conservation issues
raised by AH may range from wasted reproductive effort in threatened, parental species, when the
hybrids are sterile, to various degrees of genetic swamping when introgression takes place. We
present a review of AH cases focusing on the hybridization between wild species and their and
domesticated counterparts. By summarizing factors and conditions that most facilitate AH, we discuss
the most relevant implications from both an evolutionary and conservation-wise points of view. In
particular, we emphasize the importance of developing of demographic models to accurately estimate
the current and future extent of admixture in parental populations in order to explore and accordingly
identify the most appropriate management and conservation recommendations.