Wolf-dog hybridisation in Europe: a risk to biodiversity

Risk of loss of the genetic identity of wolf populations due to hybridisation with dogs and urgent necessity of appropriate measures for the proper management of the phenomenon: these are the main points of a new international research supervised by the Department of Biology and Biotechnology of Sapienza University of Rome and recently published on the journal Biological Conservation

Dogs are domesticated animals usually kept by humans as pets, but under degraded ecological conditions, are able to interbreed with wolves and produce viable hybrid offspring. At high and recurrent rates, such hybridisation may compromise the genetic identity of wolf populations, potentially affecting their behaviour, ecology and conservation value.

The wolf disappeared from Europe at the beginning of the last century; thanks to persistent conservation efforts, such as legal protection and habitat management, wolves have been gradually spreading across Europe in recent decades. However, such expansion is increasingly bringing wolves into agricultural landscapes where they are more likely to encounter dogs and chances for hybridisation are higher. Concurrently, poaching and hunting activities may disrupt the social cohesion of wolf packs, therefore, allowing greater opportunities for affiliative encounters between wolves and dogs.

The research, led by Valeria Salvatori of the Institute of Applied Ecology of Rome and supervised by Paolo Ciucci of the Department of Biology and Biotechnology of Sapienza University, also involved several international experts. They provided evidence of the potential presence of hybrids and management responses implemented in their countries of expertise. The study, published on Biological Conservation journal, highlighted that wolf and dog hybrids are present in all wolf populations in Europe and many European countries, including Italy, are not complying with international legal agreements, such as the Habitats Directive and the Bern Convention when it comes to the mitigation of this phenomenon.

The hybrids currently appear to be relatively few in most of the surveyed countries, and that allows the authorities to plan and implement effective prevention and control interventions. However, the research revealed that, to date, there are no international agreements and standards on how to define and manage hybridisation effectively and in a socially acceptable way.

The research also revealed further issues of concern to the experts. First the difficulty in detecting the hybrids and take action to prevent their spread on a large scale due to the lack of systematic monitoring of hybridisation in many European countries, including Italy. Secondly, the lack of comparable analysis techniques between laboratories aimed at genetically identify hybrids means that, to date, the same individual could be recognised as either a hybrid or a wolf depending on the laboratory where the biological samples are analysed.
This heterogeneity does not facilitate adequate analysis and mitigation of this phenomenon, both at national and European level.

"Another issue" – continues Ciucci – "is that hybrids can backcross with wolves through generations, becoming less dog-like and more wolf-like with every backcrossing, which leaves us with an arbitrary decision of at which point should we stop considering a backcrossed individual a hybrid and start treating it as a wolf. Today we lack scientific agreement on such definition of hybrid, which is most urgently needed to ensure all countries are working towards the same management goal."

To sum up – as suggested by the researchers – including more precise indications on the management of hybrids and stray dogs in international treaties should be of paramount importance. Wolf-dog hybrids should be protected by law and their management entrusted only to the competent authorities: the aim is to avoid cases of poaching on wolves, disguised as management interventions based on the uncertain identification of individuals considered hybrids.

References:

European agreements for nature conservation need to explicitly address wolf-dog hybridization - Valeria Salvatori, Valerio Donfrancesco, Arie Trouwborst, Luigi Boitani, John D.C.Linnell, Francisco Alvares, Mikael Åkesson, Vaidas Balysh, Juan Carlos Blanco, Silviu Chiriac, Dusko Cirovic, Claudio Groff, Murielle Guinot Ghestem, Djuro Huber, Ilpo Kojola, Josip Kusak, Miroslav Kutal, Yorgos Iliopulos…Paolo Ciucci - Biological Conservation (2020) DOI https://doi.org/10.1016/j.biocon.2020.108525