The ESBC’s 2019 breed report included an overview of sire and dam lines in the breed. As noted in that report, sire and dam lines represent unique genetic content that is transmitted only by those pedigree lineages: from fathers to sons, and from mothers to daughters. Many breeds begin with a fair number of unique of sire and dam lines but some lines drift into prominence while others become more scarce and eventually extinct. Maintaining diversity in sire and dam lines helps maintain genetic diversity in the breed.
Here is an update looking at representation and trends in sire lines through 2021. There is no getting around the fact that this kind of overview involves a lot of names… 22 sire lines, some with several branches, it can be daunting at first glance. Becoming familiar with the names and lines is important, however, as these are the dogs that set the foundation for the breed today.
ESCR Litters by Sire Line, 2019-2021
Overall, 287 stud dogs representing 22 distinct sire lines sired 564 litters during the interval.
The number of stud dogs per sire line ranged from 1 – 70, and the number of litters per sire line ranged from 1 – 138. The number of pups noted on the chart is an estimate based on an average litter size of 7.
Since all of the original sire line founders come down to the present generation through more recent (better known) descendants, we will start using those more recent “key” descendants to identify the various lines. Here are approximate dates of birth for these “key descendants” to provide a sense of where the line is with respect to our recent genetic bottleneck.
NOTE: we included Partlow’s Bobby twice on the chart above because of the large difference in size between the two branches descending from him via Partlow’s Bud II and Partlow’s Buster Brown. Given the prominence of the Partlow’s Bobby sire line it would be easy to conclude the line was not in need of ongoing attention, to retain diversity. A closer look shows that this is not the case. The chart below presents this in more detail.
There are 8 different branches along the Partlow’s Bobby sire line, 6 coming through Partlow’s Bud II and 2 through Partlow’s Buster Brown. Likewise, there were 41 active stud dogs coming through Partlow’s Bud II and only 3 stud dogs from Partlow’s Buster Brown. The number of sires and litters for each branch are noted below. Over 50% of all the stud dogs & litters on the Partlow Bobby line from 2019-2021 are on one branch (Bud II –> Dalby’s Laddie –> Egertsen’s Copperfield); there were no stud dogs or litters from a different Bud II branch (Partlow’s Bud II –> Partlow’s Odis Charles –> Boone Bubbins), nor were there any from Buster Brown’s son, Orchard Hill Gus.
It is important to keep in mind that even within well-represented lines there are pockets of diversity that need protecting.
Trends in Representation
The chart below compares the proportion of litters by sire line in 2013-2018 (blue) and 2019-2021 (orange). The largest change was a 7% increase for the Partlow’s Bud II sire line, primarily on the branch descending through Dalby’s Laddie. Some founder lines, including those going back through Compton’s Tuffy, Dawg, and Burden’s Apache, were not represented at all.
Discussion
We noted in a previous post that English Shepherds have a smaller effective population size than many realize given the relatively robust numbers of dogs available now. Some of the data here helps explain why this is the case – how the increase in population size does not automatically mean the breed is more genetically secure. It is possible for the number of dogs in the breed to increase while at the same time the number of founders – the foundation dogs that establish the breed’s gene pool – decreases. The population expands but the foundation on which it is built shrinks.
A bit of history can help illustrate how this dynamic has played out for English Shepherds. The English Shepherd population dropped to quite low numbers in the late 20th century before starting to recover in the mid-1990s to early 2000s. Recovery from that bottleneck has been very uneven, with some dogs producing many offspring at short generation intervals, while other lines reproduce at a slower pace or dwindle. Although the breed currently has a fairly large number of distinct sire lines, most dogs today come from one of a handful of lines. With each generation post-bottleneck, the effect of the narrow foundation upon which the recovery is being built becomes more apparent. This is not to say that there are “too many” dogs from any particular line but rather that all lines within the breed need to be cultivated. Over half of the sire lines available in the breed today reside in so few dogs that the lines are in jeopardy.
What concrete steps can individual breeders and groups of breeders take to conserve the genetic diversity available today? What information and tools are needed to support that work? There are a variety of steps that could be taken such as identifying and advertising available stud dogs from various lines, organizing a breed conservation program and/or breeder collective to promote preservation of diversity within the breed, utilizing a sperm bank for lines felt to be in imminent danger of being lost. We would love to hear your thoughts, suggestions, and experiences.
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