|
|
An insidious extinction of species from non-natural hybridisation |
|
|
|
I keep a watch over the threats facing the expansion of wolves in Continental Europe, as a means to anticipate and find solutions to those threats when reinstatement of wolves to Britain is taken seriously. Other than the expected fears of people that will be articulated, it is only right that the prospect for those reinstated wolves is unhindered by aspects of our anthropogenic influence that we can mitigate. There is one threat, though, that has much wider implications than just for wolves. In early 2020, park rangers in a protected area on the Italian side of the Cottian Alps photographed a pair of wolves, the very light brown coat colour of one of them being uncharacteristic of an Italian wolf (1). This animal had the typical appearances of an Italian wolf, such as triangular ears, and a large muzzle, but the coat colour suggested that it may have been a hybrid deriving from mating of a wolf with a stray or feral dog. This would be the first wolf hybrid dispersing in Piedmont and the Alps. Coat colour alone, though, is not always enough for that diagnosis (see later) and so research activities in the field were increased to try to obtain sufficient material from excrement, a tuft of hair, or even saliva or shreds of skin, to reconstruct the genetic map of this unusual wolf. The fear was that this hybridisation would put at risk the observable appearance of an Italian wolf subspecies (Canis lupus italicus) albeit that subspecies is not universally recognised; and that if the hybrid reached a dominant position in a new wolf pack, it could transmit the modified genetic pool to its offspring, and thence be spread to other territories. The field studies were in partnership with LIFE WolfAlps EU, a five-year project with the aim of ensuring the long-term conservation of the wolf in the alpine territories of France, Italy, Slovenia and Austria, through improving coexistence with the wolf (2). One of its nine major areas of intervention is control of hybridisation (3). It was recognised that hybrids were now showing up in the Alps as a dispersal from the introgressed part of the Apennine population in Tuscany, as it advanced through the ecological corridor of the Piemonte-Ligurian Apennines - introgressed meaning where hybrids had been breeding amongst themselves and their parents. It was noted that the widespread presence of dogs in Italy and the lack of control of occasional hybrids, meant that they represented a serious threat to the conservation of the genetic identity of the wolf. Different methods of control of hybridisation In 2021, an all-black male wolf appeared in a border area between Slovenia and Italy (4). The wolf, a hybrid with a domestic dog, had joined with a female wolf living in the area. Photographic evidence showed that they had formed a pack with their litter of seven hybrid offspring, the coat colour of the wolf cubs ranging from completely black, darker coloured, to an almost completely wolf-like appearance. The pack’s home range covered parts of both Italy and Slovenia. Recognised as a threat through further spreading of dog genes into the wolf population, the Ministry of Environment and Spatial Planning of the Republic of Slovenia issued a permit for the removal by shooting of the wolf-dog hybrids. It was considered that the culling would not be detrimental to the favourable status of the wolf population in Slovenia, but that not removing them would pose a serious threat to the favourable status, as it could cause irreparable damage to that wolf population. That lighter-coloured wolf photographed in the Susa Valley in Italy (see above) was seen over the following months to be well integrated in a pack, and came to be known as Biondo (blond) (5). While the evidence from genetic analysis of samples collected in the area confirmed the presence of a hybrid, it could not be attributed with certainty to Biondo, but he was the main suspect. The park authorities recognised that the presence of Biondo posed a challenge if it were to prevent further transmission of genetic material from dogs. It thus faced three options if a wolf was found from a DNA sample to be a hybrid: killing, sterilisation, or kept in captivity. This deliberation was in line with the guidelines for the management of wolf-dog hybrids in the Alpine regions developed by the LIFE WolfAlps EU (6). Consequently, a request was made by the park authorities, along with the Metropolitan City of Turin and the Piedmont Region, to the Italian Institute for Environmental Protection and Research, to capture and test Biondo (5). The request ruled out killing and to proceed instead with sterilisation, with the object of returning the wolf to live in its own territory while maintaining hierarchical and social relationships within the pack. As it was, the first hybrid wolf trapped in the Susa Valley in October 2022, as part of a wider capture and testing operation, was presumed to be one of the offspring of Biondo (7). It was a young male that was not immediately identified as a hybrid because of its typical coat colouring, but genetic analysis revealed the evidence of hybridisation. He was sterilised, equipped with a satellite collar and released by park rangers in an area close to the place of capture. Photographic evidence and satellite data soon revealed that this young wolf had reintegrated with its original pack (8). A second period of capture operations and testing conducted in April 2023 did not yield any hybrids (9) but during a third period over 10 days later in the year, a second wolf-dog hybrid was captured, quickly sterilized and released back into the wild (10). The young male, named Godot, also had a typical coat colour, but again genetic testing revealed it as a hybrid, and he too was quickly seen to return to his original pack (11). The wider European scene of wolf-dog hybridisation Wolf-dog hybrids in Europe were uncommon at the turn of the millennium, but they were detectable, as shown by various studies (12-15). It was, nevertheless, recognised as a threat in 2000 in an Action Plan for the conservation of wolves in Europe produced for the Council of Europe – “Feral and stray dogs can be a danger for the wolf as some cases of hybridisation may occur” (16). The action plan recognised the responsibility dog owners had in keeping them under control so that they did not stray or become feral, but noted that the laws on controlling feral dogs varied across Europe. It proposed that the laws be reinforced to have feral and stray dogs removed. Two other actions were required: reinforcement of regulations on owners of captive wolves and hybrids to prevent their release; and prohibition of the cross-breeding and keeping of hybrids as pets. A manifesto on wolf conservation from the Wolf Specialist Group of the Species Survival Commission of IUCN was appended , and which had this principle – “Wolf-dog hybridization is potentially detrimental to wolf conservation and is therefore opposed because of its possible negative effects” Subsequently, a document produced in 2015 for the European Commission on key actions for large carnivore populations in Europe noted hybridisation amongst the threats facing wolves (17). Action 5 for the wolf was about the control of free-ranging dogs and wolf-dog hybridization. Its objectives were to: reduce by at least 80% the current levels of owned free-ranging and stray dogs in the wolf range; to have policy and technical guidelines for the management of the hybridization between dogs and wolves approved at a national level; and to prevent and reduce the frequency of hybridisation. The report gave this action for the wolf the highest level of urgency, and almost the same level of importance was given for the benefit this action would have for the conservation of wolves. Both of the action plans above had stressed further genetic studies and improved procedures for genetic sampling and monitoring. It may seem obvious, but two genetic studies, one in Latvia, the other in Spain and Portugal, established that cross-breeding between wolves and dogs occurred both ways, a male dog with a female wolf (18) and a female dog with a male wolf (19). Other studies in European wolves followed that showed hybridisation, such as in European Russia (20) the agricultural landscapes of central Italy (21) and one that estimated a prevalence of hybridisation at 70% in the Tuscan-Emilian Apennine National Park and surrounding areas of the northern Apennines in Italy (22). An assessment of wolf-dog hybridisation in 2020 pulled together information from across Europe using a literature survey and a structured questionnaire sent to large carnivore experts in various countries (23). It showed that wolf-dog hybrids were reported in all nine extant, geographically distinct European wolf populations, ranging from the Scandinavian and the Karelian in the north, the Iberian in the west, and the Carpathian and the Dinaric-Balkan in the east – the Italian Peninsula population was the earliest for the year of first detection in 1973, followed by Serbia in the Dinaric-Balkan population in 1979. Based on the questionnaire returns, hybrids were present in 21 out of 26 countries. Of those countries that reported a presence, 18 stated that their hybrid detection relied on genetic analyses of individuals, whereas the remainder relied on coat colour or other uncharacteristic appearance traits. It is interesting to note that the incidence in the literature of reported cases of hybrids was only six between 1960-1998, a period when hybrids were not recognised as a concern by the scientific community, but it increased to 16 between 1999-2013 after it was increasingly considered a conservation issue. The authors tabulated the policies and management interventions of the countries hosting those nine populations, finding a poor level of adoption of policies, and a variation of approach – lethal removal, captivity, sterilise and release - even between those countries that shared a geographic population. They noted that no information was available from the countries consulted on what control was in place for owned, free-ranging dogs, since it was not always stray or feral dogs that caused wolf-dog hybridisation; that there was a need for national laws and policies to incorporate guidance on how to manage free-ranging wolf-dog hybrids; and that there was no comprehensive European strategy on how to effectively manage wolf-dog hybridisation. What are the implications of wolf-dog hybridisation? That concern over wolf-dog hybridisation in Europe is now a mainstream conservation issue is evidenced in a recent assessment of the conservation status of the wolf for the Council of Europe (24). The assessment covers wolf numbers in each European country and their current population trend, their legal status, livestock losses and compensation costs, and the occurrence and scale of wolf-dog-hybridisation. The assessment observes that “A note of high concern is raised by the finding that wolf-dog hybridisation is widespread across Europe, although with substantial variation in intensity: Italy, and the southern countries in general, report levels of occurrence that are (or can quickly become) very problematic for wolf conservation”. Hybridisation is characterised in the assessment as being one of four emerging threats to wolf conservation that call for particular attention and dedicated actions – “wolf-dog hybridisation is insidiously increasing its impact on several southern and eastern wolf populations: it is urgent to approve adequate policies and implement appropriate management means to prevent the spread of this serious conservation threat” Thus far, it has been a supposition that wolf-dog hybridisation was a deleterious threat to the wolf in it losing its genetic authenticity, but there is now further evidence of what that threat constitutes through a behavioural study that compared hybridised and non-hybridised wolves (25). The researchers were looking at their reaction to unfamiliar humans and novel objects, and the cohesiveness of their social groups. A note of caution that the study, while observing animals that had been derived from the wild, was carried out with them in captivity, but the observations were that the hybrids were less vigilant, less fearful and less aggressive than wolves, and they were also more likely to approach humans, without showing fearful or aggressive behaviour. When exposed to novel objects, differences between wolves and hybrids were less clear: hybrids did show less aggressive behaviours and were more likely than wolves to be in proximity of novel objects, suggesting a link between hybridisation with dogs and lower fear of anything new. Social networks were more cohesive in wolves in terms of grooming, and in social play and proximity, than in hybrids. While the authors don’t say it in such words, the wildness and pack mentality, traits that are integral to wolf survival, had been subdued in hybrids. I wonder how transferable through behavioural association those diminished traits would be on returning a sterilised hybrid wolf to the wild (see above). Sterilisation in itself can have an impact on behaviour, perhaps as profound as hybridisation with a domesticated species. The consideration of returning the hybrid to the wild was likely based on potential disruption to pack behaviour from its absence. It will be difficult to evaluate this. Long term, though, the removal of transfer of hybrid genes by whatever method is the essential action. The hybridisation of wolves with dogs also raises the possibility of a threat to our one native canid, the red fox (Vulpes vulpes) (26). Foxes in Britain have enough problems from consistent and determined rural persecution (27,28) without having to face losing their traits for survival though hybridisation with a dog. Dogs and red foxes have widely different numbers of chromosomes (78 v 34 – see (29)) and so you might have expected that hybridisation between them would be impossible. That the first ever fox-domestic dog hybrid was reported in 2021 in Brazil does not confound this, as it was a cross with a pampas fox (Lycalopex gymnocercus) a canid in an entirely different evolutionary branch to that of the red fox, but which has a similar chromosome number to the domestic dog (30). Hybridisation with domestic species is a pathway to extinction Writing in a highly cited article from 1996, Rhymer and Simberloff noted that most attention to species extinction had focussed on overkill, habitat destruction, and the impact of introduced species competing with or preying on native species, or destroying their habitat (requires registration (31) or see Simberloff’s companion article (32)). However, they argued that introduced species through an anthropogenic range expansion, or from the presence of domestic forms of species, could generate another kind of extinction, a genetic extinction by hybridisation and introgression with native flora and fauna to the point where genetic distinctiveness was lost and a lack of fitness may prevent survival. An example they gave was hybridisation in Europe between wolves and domestic and feral dogs. Amongst other examples they gave were some that immediately sprang to mind when I began to wonder what threat hybridisation may pose to British native species, and could do if we were to reinstate wolves. Wildcat was another of their examples, citing a paper from 1992 that indicated feral housecats threatened the existence of the wildcat through hybridization, because only eight of 42 putative wildcats caught in remote areas of northern and western Scotland showed clear differences by genetic analysis from domestic cats (33). I have written before about the determination in 2019 from an independent review of wildcat in Scotland that it was “at the verge of extinction” that it is “no longer viable” that the “number of wildcats is too small, the hybridisation too far advanced and the population too fragmented” (34). At that time, I felt that there was an over emphasis on hybridisation alone, rather than a parallel issue of wildcat in Scotland having become entrenched in the dead end of sub-optimal habitat due to the fragmentation and lack of native woodland and woodland networks. Earlier, I had bemoaned the tragedy of our only remaining native feline predator ending up preying on the rabbit, a non-native herbivore first introduced by the Romans (35). A camera-trap survey between January 2010 to July 2013 was carried out throughout northern Scotland to document the distribution of felines identified on the basis of their coat colour (36). There were 193 captures of feral cats, 145 of hybrids, and 87 of wildcats. Using the locations of the photographic captures, wildcat occupancy probability increased with a higher proportion of mixed woodland habitat and decreased in habitat with more edge (transition from closed to open habitats). Hybrids showed a clear overlap in their distribution pattern with both ferals and wildcats. Less of a supposition was a study of the factors influencing European wildcat genetic integrity in Europe based on using a biome specific approach and gene analysis (37). It was found that the Temperate Insular biome, which includes Scotland, encompassed the most hybridised population, the wild-living population in that biome resembling a “hybrid swarm” – a continuing process of repeated backcrossing and mating between hybrids that puts wildcat at serious risk of extinction through genetic swamping. It found that forest landscapes of high integrity were a common factor promoting European wildcat genetic integrity, and were strongholds for wildcat. In contrast the “critical conservation scenario of the Scottish wildcat population derives from a long history of isolation and considerable change in the land-management practices, including high levels of persecution combined with low forest cover and prey population densities, over the last two centuries”. That we seem to have lost sight of what constitutes the habitat selection of wildcats is a convenient blindness, typical of our overweening focus on nature in a managed, cultural landscape. This was brought home forcibly to me when I wrote about two new national parks in development, the Parc national de forêts in France, and the Hunsrück-Hochwald National Park in Germany, both of which have very high woodland cover, and both of which have wildcat, the German park claiming to have the “biggest occurrence of wildcats in Europe” (38). A study that investigated DNA from 258 archaeological cat samples (8,500–100 years BP) found that despite cohabitating for at least 2,000 years on the European mainland and in Britain, ancient European wildcats possessed little to no ancestry from domestic cats (39). The long-term resistance to introgression was explained as likely from the result of behavioural and ecological differences between wild and domestic cats that created a reproductive isolation. The authors then inferred an anthropocentric influence in initiating and increasing the hybridisation of wildcats. Thus, the reproductive isolation broke down in Britain when habitat degradation and the encroaching human presence caused a drastic reduction of the distribution of wildcats that began in the 19th century, and which intensified in the second half of the 20th century. In a follow-on study, genetic data from historic and contemporary samples from Scotland was used to date the onset of significant hybridization (40). Hybridization arose from expansion after a limited recovery from a population low estimated at 100 years ago, and the onset of significant hybridization was estimated to have begun from the late 1950s. This was explained by the authors as wildcat moving from a small area in the northwest Highlands into central Scotland, the ecological and spatial separation between wildcats and domestic cats breaking down as the wildcats moved into anthropogenic environments where domestic cats predominated. That explanation has a tangled series of assumptions, but which do not belie that wildcat has been living in sub-optimal conditions, and been persecuted, for many centuries. Hybridisation with domestic cats adds another blow, irrespective of when it started. While I can find no evidence yet of deleterious behavioural changes resulting from hybridisation between wildcats and feral domestic cats in Scotland, there is evidence of transfer of infectious agents that can cause significant clinical disease in wildcats. A total of 120 free-living cats captured in six “conservation priority areas of northern Scotland” were tested for genetic integrity as well as being screened for a range of diseases, including feline immunodeficiency virus, feline leukaemia virus, feline calicivirus, and feline herpesvirus (41). Ninety-six of the captured cats showed a range of hybridisation, 24 were domestic cats, and none were unhybridized wildcats. A total of 11 infectious agents were found. For eight of them, there was no significant association between the level of hybridisation and the prevalence of infection. That lack of association suggested to the authors that the Scottish hybrid swarm could constitute a single epidemiological unit, effectively functioning as a reservoir community for these pathogens – “Considering the impact of infectious diseases on health, welfare, and population dynamics of domestic cats, their presence in the extremely fragile and hybridised population of F. silvestris in Scotland could be population limiting or, potentially, contribute to local extinction” More examples of the threat from domesticated species – ducks, wild boar and polecat Another on my list, the European polecat (Mustela putorius) was also an example given by Rhymer and Simberloff. They observed that the polecat in Britain had declined to near extinction because of predator control to enhance gamebird shooting. As this pressure eased, the polecat was recovering, but a further threat came from hybridization with feral ferrets, a domesticated form of the polecat (and see (42,43)). A recent study probed whether the appearance of polecats was a reliable indicator of hybridisation (44). In addition, it sought to identify if there was a differential in hybridisation between those polecats that remained in refuge in central Wales during the height of its persecution, and those that had expanded the range into England. Roadkill samples from Britain were genetically tested: 16 polecats that appeared as pure and three that looked like polecat–ferret hybrids. The polecat samples were further subdivided by the location of where they were killed, with six samples from Wales (or counties bordering Wales and England) and the remaining 13 samples allocated to the English group (10 pure and the three hybrids). For comparison, they also tested 15 road-killed polecats from the European mainland, as well as eight domestic ferrets. The Welsh polecats did not have the genetic signature of the mainland samples, indicating possibly that their geographical isolation may have led to it becoming genetically distinct, to the point where it represented a distinct species. Polecats away from the Wales location showed varying degrees of introgression with domestic ferrets, the further away the more ferret-like their genomes became. It also confirmed that many of the English polecats phenotyped (assessed by appearance) as pure polecats, showed close to, or in some cases, more introgression than those phenotyped as hybrids. The last example that Rhymer and Simberloff used of wild-domestic hybridisation that was also on my list was mallard ducks (Anas platyrhynchos) although it was about domesticated, non-migratory mallards in Florida that were released for hunting, or had escaped, that were threatening the existence of the endemic Florida mottled duck (Anas fulvigula fulvigula) through introgression. Mallard ducks are known for the ease with which they have been domesticated, and then various traits selected either to produce a fancy bird for show, or that have better egg or meat production (45-47). Mallards that don’t look right are a common sight in the lakes in urban public parks. Some may just be the domestic breed, escaped or released, that we are unfamiliar with, but there will also be hybrids, all of which are capable of continuing their dilution of the original gene pool. In terms of research, most concentrates on the larger phenomenon of hybridisation that occurs in wild populations from the millions of farmed ducks released into the wild to increase the huntable population. It has been estimated that the number of mallards released in Britain was at a minimum 500,000 (48). A study undertook genetic analysis of mallards taken from the wild in six countries across Europe and compared them with samples from mallard farms, as well as historical, samples collected 1831–1977, which is before large-scale releases started (49). There was a clear genetic differentiation between wild and farmed mallards, but more worryingly the wild birds had a different genetic composition to the historical samples. These authors also combined their data with global mallard hybridisation data from an earlier paper to give a greater geographical range, and which showed that 34% of 50 samples in Britain were hybrids and 6% were farmed birds (see Table 2in (49)). A presence of wild boar living freely in England was confirmed over 30 years ago (50). I have written before questioning the genetic integrity of these wild boar when their origins were likely escapes or releases from farms that were breeding hybrids for meat (51). Distribution maps of wild boar, like that on the Mammal Society website (52) are not keeping pace with expansion, especially in Scotland (53) and a better indication is given by sightings reported to the National Biodiversity Network (54). There also doesn’t seem to be any more recent studies in the extent of hybridisation in these wild boar since the one in 2013 that found that the genetic make-up of wild boar in the Forest of Dean were a mixture of wild boar and domestic pig – “Therefore, it is debatable whether the wild boar in the Forest of Dean can be regarded as a restored native species” (55). The threat from non-native species – red deer and mountain hare Hybridisation with non-native species is an equally significant threat to that of hybridisation with domestic species. Also on my list, but under a separate category of hybridisation with introduced invasive non-native species, Rhymer and Simberloff cited a paper that said sika deer (Cervus nippon nippon) a Japanese native that had escaped from captivity in Scotland in the early twentieth century, were hybridising with native red deer (Cervus elaphus) threatening their genetic integrity (56). A more forceful opinion was voiced by Philip Ratcliffe in his paper from 1987 on the distribution and status of sika deer in Britain when he said “The introduction of Sika Deer to Red Deer areas is considered to be irresponsible because of the likelihood of hybridization and the threat to the genetic integrity of Red Deer” (57). There are now concentrations of Sika deer in the western Highlands of Scotland, the southern uplands of Scotland, the uplands of the Lake District and the Howgills, East and West Sussex, and from western Hampshire across to Devon (58). All these locations are shadowed by the greater distribution of red deer (59). A study in 2018 used DNA analysis to investigate the extent of hybridisation in nearly 3,000 deer samples from locations in Scotland and in the Lake District (60). The deer sampled from the Hebrides and the Lake District were phenotypically (identified by appearance) red deer. Deer sampled from the Central Highlands were phenotypically red deer but with a few sika deer. Samples from Kintyre and the North Highlands were phenotypically red deer, sika, or hybrid. After DNA analysis, all the deer from the Hebrides were found to be pure bred red deer, indicating the importance of these islands off the west coast of Scotland as a refugia. Samples from the Central Highlands were free from hybridisation. Almost all the red deer from the Lake District (134 out of 137) were also pure red deer, the three being hybrids with sika deer. Similarly, there were 568 pure red deer in the North Highlands, 266 pure sika, and three hybrids. In the whole of Kintyre, 617 were pure red deer, 270 were pure sika, and 165 were hybrids. Proportionately in two areas of Kintyre, West Loch Awe and South Kintyre, hybridisation was much higher, the latter being a geographically new finding. Overall, of the sika-like animals, 86 out of 606 had evidence of red deer DNA. This doesn’t seem like a high level of hybridisation when the distributions of the two species indicates that their proximity to each other would give rise to opportunity, or is there some other reason for reproductive isolation. It is, however, indicative of the mixed data in the literature, some of which may rest on increasing the efficacy of genetic analysis. A follow up study to that above, using the deer samples from Kintyre and NW Highlands, evaluated a greater number of genomic markers in detecting hybridisation, and found that 26% of deer from Kintyre, which had the highest number of hybrids (see above) had to be reclassified from the pure species categories to the hybrid category whereas in the NW Highlands only 2% were reclassified (61). I have my own example of hybridisation of a native species with an introduced, non-native species. The mountain hare (Lepus timidus) was once distributed across Britain, but with the final retreat of the glaciers, the mountain hares of England and Wales died out leaving only an extant population in Scotland, and a reintroduced population in the Peak District (62). I first saw a mountain hare in 2005 when I emerged from a conifer plantation onto the hills to the north of Kingussie (63). Years later, I was disgusted to find that mountain hares were persecuted allegedly because they were a reservoir for a tick whose bite infected grouse with a debilitating virus ((64) and see (65)) even though one review concluded there was no compelling evidence base to suggest culling mountain hares would increase red grouse densities (66). It thus seemed to me that this was a bogus excuse, as the tick was also carried by sheep and red deer. As was the nonsense argument that if unmanaged there could be problems with grazing pressure resulting in an impact on upland flora (67). So why not remove sheep instead, or don’t remove the predators that would naturally limit the numbers of mountain hares? This is the ever-downward spiral of our native trophic pyramid when it becomes inconvenient to human exploitation, in this case the number of grouse being the commercial factor. No consideration that the tick reservoir could be due to the over-population of red grouse and not the decreasing mountain hares, or even that gamekeepers killed mountain hares in an effort to make grouse moors less attractive to birds of prey that predate grouse. Mountain hares were a protected species under the Habitats Directive, and while it was the lowest level of protection (see Annex V in (68)) it did require Britain to report on its conservation status. The last such report in 2018 stated that while both the area and quality of occupied habitat, and area of unoccupied habitat of suitable quality, were sufficient, the declining population meant that its overall status should be assessed as unfavourable-inadequate (69). It said the main threats to the population came from hunting and management for game, both activities that did not require a licence outside of what was the closed season for killing in Scotland (1 March - 31 July). That closed season for mountain hares became unnecessary when Scotland recently gave greater, year-round protection to the mountain hare by adding it to Schedule 5 of the Wildlife and Countryside Act 1981 so that anyone who intentionally or recklessly killed, injured or takes mountain hare without a licence will be acting unlawfully (70,71) but it is not protected in this way in England (72). There is a brown hare (Lepus europaeus) in Britain, a non-native species introduced 2,500 years ago and which populated everywhere since (73). As a non-native species, it has none of the protection of the mountain hare, but as a game species there is a closed season for killing it in Scotland (70,71) the situation seemingly less clear in England and Wales (74,75). It is particularly galling to me that when the first UK Biodiversity Action Plan was formulated, there was a Species Action Plan for the brown hare, even though it was a non-native species ((see pg. 83 in (76)). The wording in the section on Communications and publicity in the Plan explains why this was so, when it said “Use the popularity of brown hares”. Rather than it be an ecological reason, it was the influence of its cultural significance and imagery in the countryside. Thus, you won’t find much reference to brown hare being a competitor with mountain hare for resources where they overlap, except in Ireland where it was more recently introduced as a non-native in the late nineteenth century, and where its spread was described as an invasion ecology that needed an invasive Species Action Plan (iSAP) and Eradication strategy (77). There is, though, another threat from brown hares that is not about competition for resources, and that is exemplified by another study in Ireland that determined that hybrids existed between mountain hares and brown hares, the prevalence of hybridisation being 33% of samples tested (78). Hybridisation has also been reported in Swedish and Finnish mountain hares (79) the Alps (80) and Iberia (81). The People’s Trust for Endangered Species supported a study from 2017 of the mountain hares in the Peak District (82). The study was led by Carlos Bedson for his doctoral research, and his findings have been published on evaluating survey methods for estimating mountain hare density (83) the vegetation cover that was associated with the highest density of mountain hares (84) and ecological niche modelling on habitat selection for both mountain and brown hare at present and in future climate scenarios (85). The genetic analysis carried out for his doctoral thesis is unpublished, but from roadkill and field carcass samples from 97 mountain hares and 18 brown hares, five mountain hares were found with high brown hare ancestry, and 10 with intermediate ancestry (see pg. 197 in (86)). There was one potential brown hare with intermediate ancestry. Hybridisation as a natural phenomenon I am aware that hybridisation is considered to have been an important process in the evolutionary development of new, distinct species (87) more so in plants (88) than in mammals (89). It is worrying, though, when the breakdown of geographical isolation, the erosion of ecological isolation barriers, and the cross-breeding and domestication for human gain, leads to artificial hybridization spreading out into the landscape – human involvement is associated with increased risk of hybridisation and extinction, whereas high reproductive isolation has a reduced risk (90). It is worrying when some researchers welcome this artificial hybridisation as “providing exciting systems to understand the genetic basis of adaptation and invasiveness” (91). Worse still, there is conjecture that non-natural hybridisation confers some benefit, as in one paper that “it is reasonable to hypothesize that contact between domestic cats and wildcats brings a disease burden that is at least partially offset by introgression of domestic immune genes” (40) another that hybrid polecats were facilitating the spreading expansion further into England – “Maybe hybridisation can prove the saviour of these polecat populations - and lead to new biodiversity that we can protect” (92). I revile at both of those, as I revile those who cannot exercise simple discipline in not letting their unneutered dog, cat or ferret stray, or who carelessly introduce domestically-bred hybrids or non-native species for commercial gain, their gawping novelty, or just to have something more to shoot at. It is the incorrigible human exceptionalism that there is nothing wrong for new, unnaturally derived hybrids to arise if they can be rationalised away as being better able to survive an anthropogenically altered world. Everything must be in our image – we do rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground Mark Fisher, 22 May 2024 (1) Forse avvistato il primo ibrido di lupo nel torinese, Ente di gestione delle Aree Protette delle Alpi Cozie 31 January 2020 (2) LIFE WolfAlps EU https://www.lifewolfalps.eu/en/ (3) Hybridization Control, LIFE WolfAlps EU https://www.lifewolfalps.eu/en/axes-of-intervention/controllo-dellibridazione/ (4) Hybrids are a threat to the wolf population, Slovenia Forest Service, LIFE WolfAlps EU 13 April 2022 https://www.lifewolfalps.eu/en/hybrids-are-a-threat-to-the-wolf-population/ (5) Ibridazione: il “biondo” della Valle di Susa impone una nuova sfida, Ente di gestione delle Aree Protette delle Alpi Cozie, 27 September 2022 (6) AA.VV. (2021). Linee guida per la gestione degli ibridi lupo-cane nelle Regioni alpine - Progetto LIFE18 NAT/IT/000972 LIFE WolfAlps EU – AZIONE A6 (7) Catturato, infertilizzato e liberato il primo lupo-cane ibrido in Piemonte, Ente di gestione delle Aree Protette delle Alpi Cozie 28 October 2022 (8) Il lupo-cane ibrido infertilizzato è stato riaccolto dal branco di origine, Ente di gestione delle Aree Protette delle Alpi Cozie 22 November 2022 (9) Bilancio del contenimento lupi ibridi in Val Susa, Ente di gestione delle Aree Protette delle Alpi Cozie 3 May 2023 https://www.parchialpicozie.it/news/detail/03-05-2023-bilancio-contenimento-lupi-ibridi-in-val-susa/ (10) Catturato, infertilizzato e ri-immesso in natura un ibrido lupo-cane nei Parchi delle Alpi Cozie, Ente di gestione delle Aree Protette delle Alpi Cozie 23 November 2023 (11) Godot è tornato nel branco di origine, Ente di gestione delle Aree Protette delle Alpi Cozie 14 December 2023 https://www.parchialpicozie.it/news/detail/14-12-2023-godot-e-tornato-nel-branco-di-origine/ (12) Randi, E., & Lucchini, V. (2002) Detecting rare introgression of domestic dog genes into wild wolf (Canis lupus) populations by Bayesian admixture analyses of microsatellite variation. Conservation Genetics, 3(1): 29-43 https://www.loupfrance.fr/wp-content/uploads/RandiLucchini2002ConsGen.pdf (13) Randi, E., Lucchini, V., Christensen, M. F., Mucci, N., Funk, S. M., Dolf, G., & Loeschcke, V. (2000) Mitochondrial DNA variability in Italian and East European wolves: detecting the consequences of small population size and hybridization. Conservation Biology, 14(2): 464-473 https://conbio.onlinelibrary.wiley.com/doi/abs/10.1046/j.1523-1739.2000.98280.x (14) Randi, E., & Lucchini, V. (2002) Detecting rare introgression of domestic dog genes into wild wolf (Canis lupus) populations by Bayesian admixture analyses of microsatellite variation. Conservation Genetics 3(1): 29-43 https://www.loupfrance.fr/wp-content/uploads/RandiLucchini2002ConsGen.pdf (15) Andersone, Ž., Lucchini, V., Randi, E., & Ozoliņš, J. (2002) Hybridisation between wolves and dogs in Latvia as documented using mitochondrial and microsatellite DNA markers. Mammalian biology, 67(2): 79-90 https://link.springer.com/article/10.1078/1616-5047-00012 (16) Action Plan for the conservation of the wolves (Canis lupus) in Europe, CONVENTION ON THE CONSERVATION OF EUROPEAN WILDLIFE AND NATURAL HABITATS, T-PVS (2000) 11 May 2000 (17) Boitani, L., F. Alvarez, O. Anders, H. Andren, E. Avanzinelli, V. Balys, J. C. Blanco, U. Breitenmoser, G. Chapron, P. Ciucci, A. Dutsov, C. Groff, D. Huber, O. Ionescu, F. Knauer, I. Kojola, J. Kubala, M. Kutal, J. Linnell, A. Majic, P. Mannil, R. Manz, F. Marucco, D. Melovski, A. Molinari, H. Norberg, S. Nowak, J. Ozolins, S. Palazon, H. Potocnik, P.-Y. Quenette, I. Reinhardt, R. Rigg, N. Selva, A. Sergiel, M. Shkvyria, J. Swenson, A. Trajce, M. Von Arx, M. Wolfl, U. Wotschikowsky, D. Zlatanova, 2015. Key actions for Large Carnivore populations in Europe. Institute of Applied Ecology (Rome, Italy). Report to DG Environment, European Commission, Bruxelles. Contract no. 07.0307/2013/654446/SER/B3 https://lciepub.nina.no/pdf/636025336996481569_Boitani%20IEA%20key_actions_large_carnivores_2015.pdf (18) Godinho, R., Llaneza, L., Blanco, J.C., Lopes, S., Álvares, F., García, E.J., Palacios, V., Cortés, Y., Talegón, J. and Ferrand, N., 2011. Genetic evidence for multiple events of hybridization between wolves and domestic dogs in the Iberian Peninsula. Molecular ecology, 20(24), pp.5154-5166 https://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2011.05345.x (19) Hindrikson M, Männil P, Ozolins J, Krzywinski A, Saarma U (2012) Bucking the Trend in Wolf-Dog Hybridization: First Evidence from Europe of Hybridization between Female Dogs and Male Wolves. PLoS ONE 7(10): e46465 https://doi.org/10.1371/journal.pone.0046465 (20) Korablev, M. P., Korablev, N. P., & Korablev, P. N. (2021). Genetic diversity and population structure of the grey wolf (Canis lupus Linnaeus, 1758) and evidence of wolf× dog hybridisation in the centre of European Russia. Mammalian Biology, 101(1), 91-104 https://link.springer.com/article/10.1007/s42991-020-00074-2 (21) Salvatori, V., Godinho, R., Braschi, C., Boitani, L., & Ciucci, P. (2019). High levels of recent wolf× dog introgressive hybridization in agricultural landscapes of central Italy. European Journal of Wildlife Research, 65(5), 73 https://link.springer.com/article/10.1007/s10344-019-1313-3 (22) Santostasi, N. L., Gimenez, O., Caniglia, R., Fabbri, E., Molinari, L., Reggioni, W., & Ciucci, P. (2021) Estimating admixture at the population scale: taking imperfect detectability and uncertainty in hybrid classification seriously. The Journal of Wildlife Management, 85(5): 1031-1046 https://wildlife.onlinelibrary.wiley.com/doi/10.1002/jwmg.22038 (23) Salvatori V., Donfrancesco V., Trouwborst A., Boitani L., Linnell J.D.C., Alvares F., Åkesson M., Balys V., Blanco J.C., Chiriac S., Cirovic D., Groff C., Guinot-Ghestem M., Huber D., Kojola I., Kusak J., Kutal M., Iliopulos Y., Ionescu O., Majic Skrbinsek A., Mannil P., Marucco F., Melovski D., Mysłajek R.W., Nowak S., Ozolins J., Rauer G., Reinhardt I., Rigg R., Schley L., Skrbinsek T., Svensson L., Trajce A., Trbojevic I., Tzingarska E., von Arx M., Ciucci P (2020) European agreements for nature conservation need to explicitly address wolf-dog hybridisation. Biological Conservation 248: 1085 https://www.sciencedirect.com/science/article/pii/S000632071931674X (24) Assessment of the conservation status of the Wolf (Canis lupus) in Europe. T-PVS/Inf(2022)45. Standing Committee 42nd meeting 28 November - 2 December 2022, CONVENTION ON THE CONSERVATION OF EUROPEAN WILDLIFE AND NATURAL HABITATS, Council of Europe Strasbourg, 2 September 2022 https://rm.coe.int/inf45e-2022-wolf-assessment-bern-convention-2791-5979-4182-1-2/1680a7fa47 (25) Amici, F., Meacci, S., Caray, E., Oña, L., Liebal, K., & Ciucci, P. (2024). A first exploratory comparison of the behaviour of wolves (Canis lupus) and wolf-dog hybrids in captivity. Animal Cognition, 27(1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10907477/ (26) Species – Fox – Vulpes vulpes, Mammal Society https://www.mammal.org.uk/species-hub/full-species-hub/discover-mammals/species-fox/ (27) They shoot foxes, don't they? Self-willed land January 2007 www.self-willed-land.org.uk/articles/shoot_foxes.htm (28) Red Fox Mortality & Disability, Wildlife online https://www.wildlifeonline.me.uk/animals/article/red-fox-mortality-disability (29) Graphodatsky, A.S., Perelman, P.L., Sokolovskaya, N.V., Beklemisheva, V.R., Serdukova, N.A., Dobigny, G., O’Brien, S.J., Ferguson-Smith, M.A. and Yang, F. (2008) Phylogenomics of the dog and fox family (Canidae, Carnivora) revealed by chromosome painting. Chromosome Research, 16: 129-143 https://link.springer.com/article/10.1007/s10577-007-1203-5 (30) Szynwelski, B. E., Kretschmer, R., Matzenbacher, C. A., Ferrari, F., Alievi, M. M., & de Freitas, T. R. O. (2023). Hybridization in Canids—A case study of Pampas fox (Lycalopex gymnocercus) and domestic dog (Canis lupus familiaris) hybrid. Animals, 13(15), 2505 https://www.mdpi.com/2076-2615/13/15/2505 (31) Rhymer, J. M., & Simberloff, D. (1996). Extinction by hybridization and introgression. Annual review of ecology and systematics, 27(1): 83-109 https://www.jstor.org/stable/2097230 (32) Simberloff, D. (1996). Hybridization between native and introduced wildlife species: importance for conservation. Wildlife Biology 2(3): 143-150 https://nsojournals.onlinelibrary.wiley.com/doi/full/10.2981/wlb.1996.012 (33) Hubbard, A. L., McOris, S., Jones, T. W., Boid, R., Scott, R., & Easterbee, N. (1992) Is survival of European wildcats Felis silvestris in Britain threatened by interbreeding with domestic cats?. Biological Conservation, 61(3): 203-208 https://www.sciencedirect.com/science/article/pii/000632079291117B (34) What future Wildcat in Britain? Self-willed land August 2019 www.self-willed-land.org.uk/articles/wild_cat.htm (35) The third dimension is the last refuge of the wild, Self-willed land December 2014 www.self-willed-and.org.uk/articles/third_dimension.htm (36) Kilshaw, K., Montgomery, R.A., Campbell, R.D., Hetherington, D.A., Johnson, P.J., Kitchener, A.C., Macdonald, D.W. and Millspaugh, J.J.(2016) Mapping the spatial configuration of hybridization risk for an endangered population of the European wildcat (Felis silvestris silvestris) in Scotland. Mammal Research, 61:1-11 (37) Matias, G., Rosalino, L.M., Alves, P.C., Tiesmeyer, A., Nowak, C., Ramos, L., Steyer, K., Astaras, C., Brix, M., Domokos, C. and Janssen, R. (2022) Genetic integrity of European wildcats: variation across biomes mandates geographically tailored conservation strategies. Biological Conservation, 268: p.109518 https://digital.csic.es/bitstream/10261/278826/4/Matias_etal_2022_BiolCon_postprint.pdf (38) An axis of naturalness for treescapes, Self-willed land November 2020 www.self-willed-land.org.uk/articles/axis_natural.htm (39) Jamieson, A., Carmagnini, A., Howard-McCombe, J., Doherty, S., Hirons, A., Dimopoulos, E., Lin, A.T., Allen, R., Anderson-Whymark, H., Barnett, R. and Batey, C., 2023. Limited historical admixture between European wildcats and domestic cats. Current Biology, 33(21): 4751-4760 https://www.cell.com/current-biology/fulltext/S0960-9822(23)01073-4 (40) Howard-McCombe, J., Jamieson, A., Carmagnini, A., Russo, I.R.M., Ghazali, M., Campbell, R., Driscoll, C., Murphy, W.J., Nowak, C., O’Connor, T. and Tomsett, L. (2023) Genetic swamping of the critically endangered Scottish wildcat was recent and accelerated by disease. Current Biology, 33(21): 4761-4769 https://www.cell.com/current-biology/fulltext/S0960-9822(23)01424-0 (41) Alves, B. S., Bacon, A., Langridge, K., Papasouliotis, K., Handel, I., Anderson, N. E., & Meredith, A. L. (2023). Epidemiology of a Hybrid Swarm: Evidence of 11 Feline Infectious Agents Circulating in a Population of Sympatric European Wildcat Hybrids and Free-Living Domestic Cats, in Scotland. Transboundary and Emerging Diseases 2023: Article ID 6692514 https://www.hindawi.com/journals/tbed/2023/6692514/ (42) Davison, A., Birks, J. D. S., Griffiths, H. I., Kitchener, A. C., Biggins, D., & Butlin, R. K. (1999) Hybridization and the phylogenetic relationship between polecats and domestic ferrets in Britain. Biological Conservation, 87(2): 155-161 (43) Sainsbury, K. A., Shore, R. F., Schofield, H., Croose, E., Campbell, R. D., & Mcdonald, R. A. (2019). Recent history, current status, conservation and management of native mammalian carnivore species in Great Britain. Mammal Review, 49(2): 171-188 https://core.ac.uk/download/pdf/196584973.pdf (44) Etherington, G. J., Ciezarek, A., Shaw, R., Michaux, J., Croose, E., Haerty, W., & Di Palma, F. (2022) Extensive genome introgression between domestic ferret and European polecat during population recovery in Great Britain. Journal of Heredity, 113(5): 500-515 https://academic.oup.com/jhered/article/113/5/500/6657699?login=false (45) Domestic Ducks, British Waterfowl Association https://www.waterfowl.org.uk/domestic-waterfowl/domestic-ducks/ (46) Types of Mallard Ducks, Risper Katiwa, Medium 6 April 2023 https://medium.com/@katiwarisper/types-of-mallard-ducks-7caa8b22cbbe (47) Domestic or Manky Mallards, Mike Bergin, 10,000 Birds 28 February 2011 https://www.10000birds.com/manky-mallards-domestic-feral-or-just-plain-odd-mallards.htm (48) Champagnon, J., Gauthier-Clerc, M., Lebreton, J. D., Mouronval, J. B., & Guillemain, M. (2013). Les canards colverts lâchés pour la chasse interagissent-ils avec les populations sauvages. Faune Sauvage, 298: 4-9. https://professionnels.ofb.fr/sites/default/files/pdf/RevueFS/FauneSauvage298_2013_Art1.pdf (49) Söderquist, P., Elmberg, J., Gunnarsson, G., Thulin, C.G., Champagnon, J., Guillemain, M., Kreisinger, J., Prins, H.H., Crooijmans, R.P. and Kraus, R.H. (2017) Admixture between released and wild game birds: a changing genetic landscape in European mallards (Anas platyrhynchos). European Journal of Wildlife Research 63: 1-13 https://link.springer.com/article/10.1007/s10344-017-1156-8 (50) Goulding, M. J., Roper, T. J., Smith, G. C., & Baker, S. J. (2003). Presence of free-living wild boar Sus scrofa in southern England. Wildlife Biology 9: 15-20 (51) Wild boar, beaver, and the Infrastructure Act 2015, Self-willed land March 2015 http://www.self-willed-land.org.uk/articles/boar_beaver_infra.htm (52) Species – Wild boar, Mammal Society https://www.mammal.org.uk/species-hub/full-species-hub/discover-mammals/species-wild-boar/ (53) Massei G. and Ward A. 2022. Preliminary assessment completed in 2015 of the feasibility of maintaining, limiting or eradicating feral pigs in Scotland. NatureScot Research Report 876 (54) Wild Boar, Sus scrofa Linnaeus, 1758. NBN Atlas https://species.nbnatlas.org/species/NBNSYS0000005142 (55) Frantz, A. C., Massei, G., & Burke, T. (2012). Genetic evidence for past hybridisation between domestic pigs and English wild boars. Conservation Genetics 13: 1355-1364 https://link.springer.com/article/10.1007/s10592-012-0379-1 (56) Abernethy, K. (1994) The establishment of a hybrid zone between red and sika deer (genus Cervus). Molecular Ecology 3: 551-562 https://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.1994.tb00086.x (57) Ratcliffe, P. R. (1987). Distribution and current status of sika deer, Cervus nippon, in Great Britain. Mammal Review, 17(1), 39-58 https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2907.1987.tb00047.x (58) Sika deer, British Deer Society https://bds.org.uk/information-advice/about-deer/deer-species/sika-deer/ (59) Red deer, British Deer Society https://bds.org.uk/information-advice/about-deer/deer-species/red-deer/ (60) Smith, S. L., Senn, H. V., Pérez‐Espona, S., Wyman, M. T., Heap, E., & Pemberton, J. M. (2018) Introgression of exotic Cervus (nippon and canadensis) into red deer (Cervus elaphus) populations in Scotland and the English Lake District. Ecology and Evolution 8(4): 2122-2134 https://onlinelibrary.wiley.com/doi/10.1002/ece3.3767 (61) McFarlane, S. E., Hunter, D. C., Senn, H. V., Smith, S. L., Holland, R., Huisman, J., & Pemberton, J. M. (2020) Increased genetic marker density reveals high levels of admixture between red deer and introduced Japanese sika in Kintyre, Scotland. Evolutionary Applications, 13(2): 432-441 https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12880 (62) Thulin, C. G. (2003) The distribution of mountain hares Lepus timidus in Europe: a challenge from brown hares L. europaeus? Mammal Review, 33(1), 29-42. (63) Trees in the landscape, Self-willed land June 2005 www.self-willed-land.org.uk/articles/tree_landscape.htm (64) Discriminating between the wild and not wild, Self-willed land August 2017 www.self-willed-land.org.uk/articles/wild_not_wild.htm (65) Hesford, N., Baines, D., Smith, A. A., & Ewald, J. A. (2020). Distribution of mountain hares Lepus timidus in Scotland in 2016/2017 and changes relative to earlier surveys in 1995/1996 and 2006/2007. Wildlife Biology, 2020(2): 1-11 (66) Harrison, A., Newey, S., Gilbert, L., Haydon, D. T., & Thirgood, S. (2010). Culling wildlife hosts to control disease: mountain hares, red grouse and louping ill virus. Journal of Applied Ecology, 47(4): 926-930 https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2664.2010.01834.x (67) The continuing destruction of our native trophic pyramid, Self-willed land February 2018 www.self-willed-land.org.uk/articles/spiral_down.htm (68) Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A01992L0043-20130701 (69) Conservation status assessment for the species: S1334 ‐ Mountain hare (Lepus timidus) European Community Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora (92/43/EEC) Fourth Report by the United Kingdom under Article 17 on the implementation of the Directive from January 2013 to December 2018 https://jncc.gov.uk/jncc-assets/Art17/S1334-UK-Habitats-Directive-Art17-2019.pdf (70) Protected species: hares. NatureScot (71) Hares and licensing – NatureScot can licence control of mountain hare throughout the year or brown hare in the closed season (72) Schedule 5, Wildlife and Countryside Act 1981 https://www.legislation.gov.uk/ukpga/1981/69/schedule/5 (73) Species: Brown Hare - Lepus europaeus, Mammal Society https://www.mammal.org.uk/species-hub/full-species-hub/discover-mammals/species-brown-hare/ (74) Brown hare, People's Trust for Endangered Species https://ptes.org/get-informed/facts-figures/brown-hare/ (75) Brown hare, Game and Wildlife Conservation Trust National Gamebag Census & Tracking Mammals Partnership (76) Brown Hare (Lepus Europaeus) Mammals, Annex G: The Action Plans, Biodiversity: The UK Steering Group Report Volume 2: Action Plans (Annex F and Annex G) 1995 (77) Reid, N. (2011) European hare (Lepus europaeus) invasion ecology: implication for the conservation of the endemic Irish hare (Lepus timidus hibernicus). Biological Invasions 13: 559-569 (78) Reid, N., Hughes, M. F., Hynes, R. A., Montgomery, W. I., & Prodöhl, P. A. (2022). Bidirectional hybridisation and introgression between introduced European brown hare, Lepus europaeus and the endemic Irish hare, L. timidus hibernicus. Conservation Genetics, 23(6): 1053-1062 https://link.springer.com/article/10.1007/s10592-022-01471-5 (79) Levänen R, Thulin C-G, Spong G, Pohjoismäki JLO (2018) Widespread introgression of mountain hare genes into Fennoscandian brown hare populations. PLoS ONE 13(1): e0191790. https://doi.org/10.1371/journal.pone.0191790 (80) Schai-Braun, S. C., Schwienbacher, S., Smith, S., & Hackländer, K. (2023). Coexistence of European hares and Alpine mountain hares in the Alps: what drives the occurrence and frequency of their hybrids?. Journal of Zoology, 320(3), 214-225. https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1111/jzo.13067 (81) Marques, J.P., Farelo, L., Vilela, J., Vanderpool, D., Alves, P.C., Good, J.M., Boursot, P. and Melo-Ferreira, J. (2017) Range expansion underlies historical introgressive hybridization in the Iberian hare. Scientific Reports, 7(1): p.40788 https://www.nature.com/articles/srep40788 (82) Mountain hares in the Peak District, People’s Trust for Endangered Species https://ptes.org/grants/uk-mammal-projects/mountain-hares-peak-district/ (83) Bedson, C.P., Thomas, L., Wheeler, P.M., Reid, N., Harris, W.E., Lloyd, H., Mallon, D. and Preziosi, R., 2021. Estimating density of mountain hares using distance sampling: A comparison of daylight visual surveys, night-time thermal imaging and camera traps. Wildlife Biology, 2021(3), pp.wlb-00802 (84) Bedson, C. P., Devenish, C., Symeonakis, E., Mallon, D., Reid, N., Harris, W. E., & Preziosi, R. (2021). Splitting hares: current and future ecological niches predicted as distinctly different for two congeneric lagomorphs. Acta Oecologica, 111, 103742 https://www.sciencedirect.com/science/article/pii/S1146609X21000412?via%3Dihub (85) Bedson, C. P., Wheeler, P. M., Reid, N., Harris, W. E., Mallon, D., Caporn, S., & Preziosi, R. (2022). Highest densities of mountain hares (Lepus timidus) associated with ecologically restored bog but not grouse moorland management. Ecology and Evolution, 12(4), e8744 https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.8744 (86) Bedson, C. P. (2022). Population assessment of the mountain hares (Lepus timidus) of England: distribution, abundance and genetics (Doctoral dissertation, Manchester Metropolitan University) https://e-space.mmu.ac.uk/629925/2/BEDSON_PHD_THESIS_220621.pdf (87) Abbott, R., Albach, D., Ansell, S., Arntzen, J.W., Baird, S.J., Bierne, N., Boughman, J., Brelsford, A., Buerkle, C.A., Buggs, R. and Butlin, R.K. (2013) Hybridization and speciation. Journal of evolutionary biology, 26(2): 229-246 https://academic.oup.com/jeb/article/26/2/229/7318699?login=false (88) Vallejo-Marín, M., & Hiscock, S. J. (2016). Hybridization and hybrid speciation under global change. New Phytologist, 211(4): 1170-1187 https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.14004 (89) Dowling, T. E., & Secor, C. L. (1997). The role of hybridization and introgression in the diversification of animals. Annual review of Ecology and Systematics 28(1): 593-619 https://www.nativefishlab.net/publications/pubs%20w%20no%20ref/Dowling_and_Secor_1997.pdf (90) Todesco, M., Pascual, M.A., Owens, G.L., Ostevik, K.L., Moyers, B.T., Hübner, S., Heredia, S.M., Hahn, M.A., Caseys, C., Bock, D.G. and Rieseberg, L.H., 2016. Hybridization and extinction. Evolutionary applications 9(7): 892-908 https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12367 (91) Peñalba, J.V., Runemark, A., Meier, J.I., Singh, P., Wogan, G.O., Sánchez-Guillén, R., Mallet, J., Rometsch, S.J., Menon, M., Seehausen, O. and Kulmuni, J. (2024) The Role of Hybridization in Species Formation and Persistence. Cold Spring Harbor perspectives in biology, p.a041445 (92) Are polecat-ferret hybrids good for conservation? Peter Bickerton, Earlham Institute 26 July 2021 https://www.earlham.ac.uk/articles/are-polecat-ferret-hybrids-good-conservation url:www.self-willed-land.org.uk/articles/hybridisation.htm www.self-willed-land.org.uk mark.fisher@self-willed-land.org.uk |
