New Genetic Research Shows Extent of Cross-Breeding between Wild Wolves and Domestic Dogs across Europe and Asia

Original article can be found online.

Mating between domesticated dogs and wild wolves over hundreds of years has left a genetic mark on the wolf gene pool, new research has shown.

The international study showed that around 60 per cent of Eurasian grey wolf genomes carried small blocks of the DNA of domestic dogs, suggesting that wolves cross-bred with dogs in past generations.

The results suggest that wolf-dog hybridisation has been geographically widespread in Europe and Asia and has been occurring for centuries. The phenomenon is seen less frequently in wild wolf populations of North America.

Researchers examined DNA data from grey wolves – the ancestors of the domestic dog – to determine how much their gene pool was diluted with the DNA of domestic canines, and how widespread the process of hybridisation is.

Despite the evidence of hybridisation among Eurasian grey wolves, the wolf populations have remained genetically distinct from dogs, suggesting that such cross-breeding does not diminish distinctiveness of the wolf gene pool if it occurs at low levels.

The results could have important conservation implications for the grey wolf, which is a keystone species – meaning it is vital to the natural balance of the habitat it occupies. The legal status of hybrids is still uncertain and unregulated.

The study was led by researchers from the University of Lincoln, UK, the Italian National Institute for Environmental Protection and Research and the University of California, Los Angeles.

Dr Malgorzata Pilot, from the School of Life Sciences at the University of Lincoln, said: “The fact that wild wolves can cross-breed with dogs is well-documented, but little was previously known about how widespread this phenomenon has been and how it has affected the genetic composition of wild wolf populations.

“We found that while hybridisation has not compromised the genetic distinctiveness of wolf populations, a large number of wild wolves in Eurasia carry a small proportion of gene variants derived from dogs, leading to the ambiguity of how we define genetically ‘pure wolves’.

“Our research highlighted that some individual wolves which had been identified as ‘pure wolves’ according to their physical characteristics were actually shown to be of mixed ancestry. On the other hand, two Italian wolves with an unusual, black coat colour did not show any genetic signatures of hybridisation, except for carrying a dog-derived variant of a gene linked to dark colouration. This suggests that the definition of genetically ‘pure’ wolves can be ambiguous and identifying admixed individuals can be difficult, implying that management strategies based on removal of suspected hybrids from wolf populations may be inefficient.

“Instead, our study has highlighted a need to reduce the factors which can cause hybridisation, such as abundance of free-ranging dogs, small wolf population sizes, and unregulated hunting.”

Studying a specific type of genetic variation in the DNA sequences of wolves and domestic dogs – called Single Nucleotide Polymorphisms (SNPs) – the scientists identified the transfer of dog gene variants into wolf genomes.

A single DNA sequence is formed from a chain of four nucleotide bases and if some individuals in a population do not carry the same nucleotide at a specific position in the sequence, the variation is classified as an SNP.

This study was funded by a Leverhulme Trust Research Fellowship, the University of Lincoln, the Polish Committee for Scientific Research, the Italian Ministry of Environment, the US National Science Foundation, the Intramural Program of the National Human Genome Research Institute, and the Italian National Institute for Environmental Protection and Research.

In the US, research collaborators were from Princeton University, the National Human Genome Research Institute based at the National Institutes of Health in Maryland, and UCLA.

The international team also included researchers from the Italian National Institute for Environmental Protection and Research, Aalborg University in Denmark, the Mammal Research Institute, and the Institute of Nature Conservation, both at the Polish Academy of Sciences, as well as the Institute of Zoology at the National Academy of Sciences of Belarus.

The findings have been published in the journal Evolutionary Applications, and the full study can be found here: https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12595.

New insights into evolutionary history of the grey wolf

Research by Life Sciences academic Dr Malgorzata Pilot has revealed new insights into the evolutionary history of the grey wolf in Europe.

Dr Pilot and the international research team analysed the evolutionary relationships among the three largest European populations of grey wolves based on genome-wide variability of these populations.

The results of the study, ‘Genome-wide signatures of population bottlenecks and diversifying selection in European wolves’ have been published in the official journal of the Genetics Society Heredity.

Dr Pilot said: “Our results suggest a continuous decline in wolf numbers in Europe since the Late Pleistocene as well as long-term isolation and demographic bottlenecks in the Iberian and Italian populations.”

The research revealed that Eastern European wolves show more genetic similarity to Asian wolves than to Italian and Iberian wolves. Italian wolves are particularly distinct from other wolf populations, which likely results from a long-term bottleneck that have occurred in this population.

Despite historical bottlenecks, the Italian and Iberian wolf populations do not show signatures of recent inbreeding, i.e. breeding between close relatives. This is in contrast to wolf populations that were recently established (such as in the Scandinavian Peninsula or on Isle Royale, US) or underwent recent drastic declines (such as Mexican wolves).

The fact that long-term historical bottlenecks can be distinguished from recent demographic declines and founder events solely based on genomic data may be important in studies on some endangered species where genetic variability is the only source of information. The team also found signatures of diversifying selection in genes involved in growth and skeletal development, which may influence differences in body size between wolf populations in Europe. Further study is needed to assess the role of these candidate genes in the adaptive diversification of grey wolves and other large canids like coyotes and jackals.

 

Darwinism expert to present lecture

One of Britain’s best-known proponents of Darwinism and evolutionary theory will be sharing his typically forthright views at a special event in Lincoln.

Professor of Genetics, science writer, broadcaster and supporter of humanism, Steve Jones, will be giving a lecture entitled “Is Man just another Animal? The View from the Genes” at the University of Lincoln on 5th March, 2013.

Professor Jones is best known to the general public as a broadcaster and writer of popular science books. He has written and presented a Radio 3 series on science and the arts, Blue Skies, and a TV series on human genetics, In the Blood. He also appears on other radio and TV programmes, such as Today, Question Time, In Our Time, Any Questions, Start the Week, Late Review and Newsnight, and writes a regular column in The Daily Telegraph.

As Professor Jones says, he is one of the world’s six greatest experts on the evolutionary genetics of land snails (and the other five agree). He also has an interest in human genetics and evolution and is recognised for his staunch and outspoken defence of science against the “anti-science”, creationism included.

Speaking to The Guardian in 2008, Professor Jones said: “It is my profound hope (likely to be disappointed) that teachers and everyone else should learn to stop treating Darwin as a prophet, or a pariah, or a philosopher, or even as a trained ecclesiastic who turned to atheism – and just take him for what he was, the greatest biologist in history. He made biology into a single science linked by the idea of evolution, rather than a bunch of ideologies.”

Professor Jones is an Emeritus Professor of Human Genetics at the Department of Genetics, Evolution and Environment at University College London and has also held visiting posts at Harvard University, the University of Chicago, the University of California at Davis, University of Botswana, Fourah Bay College in Sierra Leone and Flinders University in Adelaide.

His many awards include the Rhone-Poulenc book prize and the Yorkshire Post first book prize in 1994; the Royal Society Faraday Medal for public understanding of science in 1997; the BP Natural World Book Prize in 1999 and 2000; the Institute of Biology Charter Medal in 2002; and the Irwin Prize for Secularist of the Year in 2006. He is a Fellow of the Royal Society and of the Royal Society of Literature.

Dr Rajiv Machado, who invited Professor Jones to the University, said: “This is a fantastic opportunity for students and staff to hear from one of the best renowned theorists in evolutionary genetics of our generation. We are extremely lucky to have Professor Jones present a lecture to the University and I have no doubt that it will be informative, thought-provoking and progressive.”

Professor Jones will be giving his guest lecture to an invited audience from 4pm in the Co-op Lecture Theatre.