IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Senn, H.; Ogden, R. | |
| Wildcat hybrid scoring for conservation breeding under the Scottish wildcat conservation action plan | |
| 2015 Full Book | |
This document is designed to set out the genetic system for determining hybridisation and how it should be integrated with morphological data, in putative specimens of the wildcat (_Felis silvestris_) destined to be brought into a conservation breeding programme, overseen by the Royal Zoological Society of Scotland as part of the Scottish Wildcat Conservation Action Plan (SNH 2013). 2. Wildcats hybridise with the domestic cat and produce fertile offspring. 3. In the absence of whole genome sequencing, a sample of genetic markers are capable of estimating the extent of hybridism in an individual with an associated degree of confidence. Wildcat phenotype provides further assessments of wildcat ancestry. 4. The test system devised by RZSS to select the animals for conservation breeding with the greatest available proportion of wildcat ancestry, employs 35 nuclear SNP DNA markers and one mitochondrial marker in combination with pelage assessments. The genetic test is based on one of the more powerful (83 SNP) tests currently available, developed in Switzerland, and has the advantage of generating data that can be compared to datasets for wildcats across Europe. It produces very similar estimates of hybridism to the Swiss test, has a slightly lower degree of confidence associated with them, but is faster and more cost-effective to run. 5. Testing of cat samples collected from across Scotland indicates that there is a complete genetic continuum between wild and domestic cat genetic types in the wild/feral cat population. From the relatively limited sampling to date, the wild-living cat population is a hybrid swarm, i.e. most individuals demonstrate some level of hybridisation. 6. Any method of choosing "wildcats" for a conservation breeding programme needs to decide on a cut-off between wildcat and domestic cat types. 7. We suggest that as a general principle we choose cats in which we have a 95% confidence of them being closer than a first generation backcross to wildcat based on their genetic scores. A first generation backcross to wildcat is a cat where one of its four grandparents is a domestic cat and the remaining three are wildcats. 8. Based on the limited evidence currently available, there does not always appear to be good correspondence between the genetic test and the commonly used phenotypic test (pelage score). This is likely because hybridisation in Scotland has been occurring for a long time and the phenotypic traits are under the control of very few genes that do not match the areas examined in the genetics test. However, this correspondence requires further analysis from a larger sample of individuals with a range of phenotypes and genotypes. 9. We propose that genetic and phenotypic tests are used as separate, independent lines of evidence, when decisions are made about cats. Only where the two lines of evidence corroborate should we chose cats for the conservation breeding programme. |
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