Hybridisation in British mammals

Species definitions are discussed, with particular reference to biological species concepts and the conservation viewpoint. Techniques available for examining differences between populations and species of animals are reviewed. The most recent techniques using nuclear or mitochondrial DNA have been effectively used in hybridisation studies of mammal species. The occurrence of hybridisation between four pairs of British mammals are examined in detail. Hybridisation between mountain hare and brown hare is very rare under natural conditions and hybrids in Britain would appear to present only novelty value. The genetic mix of red and sika deer in Britain is complex. Morphometric studies have suggested that hybridisation between these two species is widespread in some areas. Current investigations using molecular and genetic techniques hope to further evaluate the real extent of hybridisation and introgression. Current evidence suggests that introgression of sika into the red deer populations will increase rather than decrease. Whether wildcats and domestic cats can be considered to be subspecies or separate species is unresolved. Past European studies, mainly skull morphometrics, suggested that hybridisation between the two types was widespread. The proportion of hybrids within a population has yet to be objectively measured. Current research in Scotland is using DNA techniques, sampling living and historic cats across Scotland. British ferrets are probably domesticated directly from European polecats. The recent spread of polecats from Wales into the English Midlands may lead to the introgression of domestic genes into wild polecats. However, it is not known to what extent feral ferrets survive in mainland Britain, and as yet hybridisation is not perceived as a substantial threat to the species. Examples of hybridisation in British Birds and fish are summarised. Many bird species hybridise and the reasons for this are discussed. Conservation issues concerning ruddy ducks, crossbills and goshawks are briefly outlined. In conclusion, the two mammals at greatest risk from hybridisation and subsequent loss of native type, are the wildcat and red deer. The importance of maintaining native habitat for native species is also stressed. It is recommended that studies initiated using modern molecular techniques be followed through, and that hypotheses based on these findings, about the ecological/behavioural reasons for hybridisation be investigated. Even though the best methods available are used, it should be recognised that descriptions of a species for legal purposes will contain a degree of subjectivity

A cost effective method for protecting livestock against marten predation

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Ecology and genetics of wild-living cats in the north-east of Scotland and the implications for the conservation of the wildcat

1. The wildcat is considered to be threatened by interbreeding with the domestic cat. As a result of interbreeding the definition of a wildcat in Scotland is contentious. Many authors consider pelage characteristics to be diagnostic, yet few data exist on sympatric cats with different pelages. 2. A study of 31 wild-living cats was conducted from 1995 to 1997 in an area associated with wildcats. Seventy-four percent of cats caught had striped tabby pelages while 26% had other (non-tabby) phenotypes. 3. On the basis of data from eight nuclear DNA microsatellite loci there was no strong evidence of two groups, and tabby and non-tabby cats did not depart significantly from Hardy - Weinberg equilibrium. 4. There were significant differences in gene frequencies and genotypes between the two pelage types. Non-tabby cats were also significantly more similar to domestic cats than tabby cats, although still noticeably differentiated from them. 5. There were potential parent - offspring and sibling - sibling relationships between and within tabby and non-tabby cats, suggesting recent interbreeding. On average, however, non-tabby cats were genetically less related to each other than tabby cats. 6. Radio-tracking revealed that non-tabby adult females had significantly larger home ranges than tabby adult females. However, for all other aspects of home range size, social organization, activity patterns and habitat use there were no significant differences between cats of different pelage type. 7. The implications of these results are that traditional approaches for attempting to distinguish wild animals in the face of interbreeding with their domestic forms are neither accurate nor effective. Instead, conservation should focus on mechanisms for dealing with groups of animals below the species level. 8. Specifically for the wildcat in Scotland, conservation should focus on protection by area. If domestic cat controls were conducted within specified areas then the potential threat posed by interbreeding would be reduced

Hybridisation in British mammals

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