Population analysis of the Anatolian Shepherd Dog breed Genetic analysis of the Kennel Club pedigree records of the UK Anatolian Shepherd Dog population has been carried out with the aim of estimating the rate of loss of genetic diversity within the breed and providing information to guide a future sustainable breeding strategy. The population statistics summarised provide a picture of trends in census size, the number of animals used for breeding, the rate of inbreeding and the estimated effective population size. The rate of inbreeding and estimated effective population size indicate the rate at which genetic diversity is being lost within the breed. The analysis also calculates the average relationship (kinship) among all individuals of the breed born per year and is used to determine the level of inbreeding that might be expected if matings were made among randomly selected dogs from the population (the expected rate of inbreeding). Summary of results The analysis utilises the complete computerised pedigree records for the current UK Kennel Club registered Anatolian Shepherd Dog population, and statistics were calculated for the period 1980-2014. 1
Figure 1: a plot of number of registrations by year of birth, indicative of any changing trend in popularity of the breed, followed by the yearly trend in number of animals registered (and 95% confidence interval). Breed: Anatolian Shepherd Dog Figure 1: Number of registrations by year of birth Trend of registrations over year of birth (1980-2014) = -1.45 per year (with a 95% confidence interval of -2.51 to -0.39). 2
Table 1: census statistics by year, including sire use statistics. Table 1: by year (1980-2014), the number of registered puppies born, by the number of unique dams and sires; maximum, median, mode, mean and standard deviation of number of puppies per sire; and the percentage of all puppies born to the most prolific 50%, 25%, 10% and 5% of sires. year #born #dams #sires puppies per sire %puppies sired by most prolific sires max median mode mean sd 50% sires 25% sires 10% sires 5% sires 1980 7 5 5 2 1 1 1.4 0.55 n/a n/a n/a n/a 1981 25 6 5 10 4 1 5 3.87 n/a n/a n/a n/a 1982 35 11 11 15 1 1 3.18 4.21 85.71 68.57 42.86 42.86 1983 60 7 6 19 9.5 2 10 5.8 n/a n/a n/a n/a 1984 63 13 9 12 7 4 7 3.24 n/a n/a n/a n/a 1985 77 20 15 13 4 1 5.13 4.22 85.71 54.55 33.77 16.88 1986 124 20 17 26 7 2 7.29 6.04 79.84 50 32.26 20.97 1987 76 16 12 16 6 2 6.33 4.75 81.58 50 21.05 21.05 1988 135 23 16 29 7 7 8.44 6.22 70.37 46.67 30.37 21.48 1989 131 23 13 43 7 4 10.08 10.82 81.68 55.73 32.82 32.82 1990 88 15 13 14 6 1 6.77 4.21 78.41 43.18 15.91 15.91 1991 85 14 9 22 9 9 9.44 6.46 n/a n/a n/a n/a 1992 96 19 14 16 5.5 5 6.86 4.13 71.88 50 16.67 16.67 1993 102 17 13 13 8 7 7.85 3.11 67.65 35.29 12.75 12.75 1994 112 17 10 23 10 5 11.2 6.01 70.54 49.11 20.54 20.54 1995 62 12 10 16 4 4 6.2 5.18 79.03 62.9 25.81 25.81 1996 71 13 10 22 4.5 1 7.1 7.25 88.73 69.01 30.99 30.99 1997 32 6 5 14 5 1 6.4 5.18 n/a n/a n/a n/a 1998 40 7 6 11 6.5 2 6.67 3.44 n/a n/a n/a n/a 1999 50 11 11 11 4 1 4.55 3.05 80 50 22 22 2000 38 7 6 11 8 1 6.33 4.32 n/a n/a n/a n/a 2001 48 12 11 9 5 1 4.36 2.8 81.25 47.92 18.75 18.75 2002 53 9 6 19 7 1 8.83 7.96 n/a n/a n/a n/a 2003 42 8 8 11 6 1 5.25 3.99 n/a n/a n/a n/a 2004 67 11 11 12 6 6 6.09 3.11 71.64 41.79 17.91 17.91 2005 43 7 9 12 5 1 4.78 3.77 n/a n/a n/a n/a 2006 65 11 9 15 6 6 7.22 3.83 n/a n/a n/a n/a 2007 44 12 11 14 1 1 4 4.2 88.64 63.64 31.82 31.82 2008 48 7 6 14 8.5 11 8 4.82 n/a n/a n/a n/a 2009 39 8 6 16 5 3 6.5 4.93 n/a n/a n/a n/a 2010 16 4 2 15 8 1 8 9.9 n/a n/a n/a n/a 2011 56 7 6 15 9.5 5 9.33 3.61 n/a n/a n/a n/a 2012 23 3 3 11 9 3 7.67 4.16 n/a n/a n/a n/a 2013 16 3 3 9 6 1 5.33 4.04 n/a n/a n/a n/a 2014 0 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a 3
Generation interval: the mean average age (in years) of parents at the birth of offspring which themselves go on to reproduce. Mean generation interval (years) = 4.14 Figure 2: a plot of the annual mean observed inbreeding coefficient (showing loss of genetic diversity), and mean expected inbreeding coefficient (from random mating ) over the period 1980-2014. Expected inbreeding is staggered by the generation interval and, where >2000 animals are born in a single year, the 95% confidence interval is indicated. Figure 2: Annual mean observed and expected inbreeding coefficients 4
Estimated effective population size: the rate of inbreeding (slope or steepness of the observed inbreeding in Figure 2) is used to estimate the effective population size of the breed. The effective population size is the number of breeding animals in an idealised, hypothetical population that would be expected to show the same rate of loss of genetic diversity (rate of inbreeding) as the breed in question. It may be thought of as the size of the gene pool of the breed. Below an effective population size of 100 (inbreeding rate of 0.50% per generation) the rate of loss of genetic diversity in a breed/population increases dramatically (Food & Agriculture Organisation of the United Nations, Monitoring animal genetic resources and criteria for prioritization of breeds, 1992). An effective population size of below 50 (inbreeding rate of 1.0% per generation) indicates the future of the breed many be considered to be at risk (Food & Agriculture Organisation of the United Nations, Breeding strategies for sustainable management of animal genetic resources, 2010). Where the rate of inbreeding is negative (implying increasing genetic diversity in the breed), effective population size is denoted n/a. Estimated effective population size = 150.6 NB - this estimate is made using the rate of inbreeding over the whole period 1980-2014 5
Table 2: a breakdown of census statistics, sire and dam usage and indicators of the rate of loss of genetic diversity over 5 year periods (1980-4, 1985-9, 1990-4, 1995-9, 2000-4, 2005-9, 2010-14). Rate of inbreeding and estimated effective population size for each 5-year block can be compared with the trend in observed inbreeding in Figure 2. Table 2: by 5-year blocks, the mean number of registrations; for sires the total number used, maximum, mean, median, mode, standard deviation and skewness (indicative of the size of the tail on the distribution) of number of progeny per sire; for dams the total number used, maximum, mean, median, mode, standard deviation and skewness of number of progeny per dam; rate of inbreeding per generation (as a decimal, multiply by 100 to obtain as a percentage); mean generation interval; and estimated effective population size. years 1980-1984 1985-1989 1990-1994 1995-1999 2000-2004 2005-2009 2010-2014 Mean #registrations 38 108.6 96.6 51 49.6 47.8 22.2 Total #sires 24 47 33 31 29 29 10 Max #progeny 42 50 51 36 46 39 27 Mean #progeny 7.875 11.511 14.606 8.1935 8.069 8.1379 10.5 Median #progeny 5.5 8 10 4 6 6 9.5 Mode #progeny 1 1 9 1 1 1 1 SD #progeny 9.3451 11.678 11.776 9.0016 10.382 9.203 8.7464 Skew #progeny 2.2334 1.822 1.3672 1.4867 2.4817 1.8528 0.87119 Total #dams 28 73 60 39 35 34 14 Max #progeny 36 22 26 26 43 18 18 Mean #progeny 6.75 7.411 8.0333 6.5128 7.0571 6.9412 7.4286 Median #progeny 4.5 7 7 6 6 6.5 7.5 Mode #progeny 1 7 5 1 1 1 9 SD #progeny 7.4963 4.9689 4.7442 4.8929 8.3558 4.9048 4.5525 Skew #progeny 2.328 0.91233 1.1834 1.6512 2.8368 0.54589 0.54866 Rate of inbreeding 0.023633 0.000283 0.062138 0.031653 0.053692-0.07586 n/a Generation interval 2.3626 3.6321 4.4917 5.4077 4.226 4.7299 n/a Effective pop size 21.156 1769.5 8.0466 15.796 9.3124 n/a n/a 6
Figure 3: a histogram ( tally distribution) of number of progeny per sire and dam over each of the seven 5-year blocks above. A longer tail on the distribution of progeny per sire is indicative of popular sires (few sires with a very large number of offspring, known to be a major contributor to a high rate of inbreeding). Figure 3: Distribution of progeny per sire (blue) and per dam (red) over 5-year blocks (1980-4 top, 2010-14 bottom). Vertical axis is a logarithmic scale. 7
Comments As can be seen from figure 1, the number of animals of this breed registered with the Kennel Club is fairly small. The small population size and possible influence of migrant animals mean there may be large fluctuations in the rate of inbreeding and effective population size. There appears to be evidence of only modest use of popular sires in this breed (the 'tail' of the blue distribution in figure 3). It should be noted that, while animals imported from overseas may appear completely unrelated, this is not always the case. Often the pedigree available to the Kennel Club is limited in the number of generations, hampering the ability to detect true, albeit distant, relationships. 8