Local populations and inaccuracies: Determining the relevant mitochondrial haplotype distributions for North West European cats

- Feline mtDNA distributions within North West Continental Europe are comparable.
- One haplotype is dominant in the Continental European populations studied to date.
- Significant differences between Continental European, UK and American cats are noted.
- Local variations and the presence of micropopulations severely impact distributions.
- Selection of the relevant population is needed for forensic casework.

Typing of different portions of the feline mitochondrial control region has illustrated pronounced differences in haplotype distributions between cats from the Netherlands and other parts of the world. To gain a better understanding of the haplotype distribution of North West Continental Europe, 605 bp of mitochondrial DNA was typed from randomly selected cats from the Netherlands (N = 146), Belgium (N = 64) and South West Germany (N = 128). The genetic differences between these randomly sampled European populations correlate to the geographical distances, with the Dutch and the South West German populations furthest apart and the Belgian population as an intermediate (Fst values 0.01-0.03).Comparison of North West European mainland distributions to published feline mitochondrial haplotype distributions illustrated moderate to large genetic differentiation (Fst values 0.01-0.32). In this comparison, the correlation between geographical and genetic distance was absent, leading to founder effects and human impact on cat population structure and dispersion being considered as important parameters.When an accurate estimation of feline haplotype distribution is required in forensics, care should be taken when deciding whether extrapolating the frequency data from a certain source to a larger area (country/continent) is justified or whether additional typing of local populations is necessary. This may differ from case to case as local frequencies can be relevant, but can also be deceitful. To improve the applicability of forensic feline mitochondrial DNA studies, documentation and publishing of sampling strategies is advised, as is the implementation of measures to help eliminate potentially erroneous haplotypes.