Sire and Dam Line Diversity, 2019
Excerpt from “Population Genetics in Practice,” by Jeffrey Bragg
“There are two unique points of canine pedigree diversity that are not always paid much attention. These are the topmost and bottommost lines of the pedigree — the tail-male or sire-line and the tail-female or dam-line. They represent unique genetic content, held by the mitochondrial DNA and the sex chromosomes, much of which is transmitted only by those pedigree lineages… diversity in sire and dam lines is often quite scarce in purebred dog genomes.
…Since these lines are not consistently scrutinized and conserved by breeders (because they are unknown if the breeder has not researched the pedigree all the way back to breed foundation), they are subject to changes in the frequency of their occurrences, exactly similar to the changes in gene frequency that occur due to random drift. Most breeds begin with a fair number of unique sire and dam lines. But some drift into prominence and others into obscurity, scarcity, and finally extinction…
The breeder should know the available unique sire and dam-lines in her breed and within her own kennel, and should make every effort to conserve them. That means ensuring that the sons of sires contribute to the next generation, likewise the daughters of dams. It is all too easy to neglect this vital point. Loss of tail-male and tail-female lines within kennels leads quickly to their loss within breed populations.”
Key Points from 2019 Breed Report
- Founder imbalance exists following genetic bottleneck
- Rare lines are down to very few remaining descendants
- Most English Shepherd breeding dogs produce only 1 or 2 litters
- Less than 30% of litters produce a male that becomes breeding stock
- Roughly 40% of litters produce a female that becomes breeding stock
Given these facts, the breed could easily lose unique sire and dam lines within the next 5 years. Preventing this requires:
- Identifying sire and dam lines with few remaining descendants
- Ensuring sons of rare sires, and daughters of rare dams, are evaluated as prospective breeding stock for the next generation
What Constitutes “Rare”
For our purposes, the term “rare” implies danger of losing the genetic diversity provided by unique founders because the number of their descendants in the breeding population has dropped below some threshold. While the exact level of that threshold is debatable it only takes a single generation for a line to be lost permanently. The fewer the number of representatives of a line, the easier it is for those losses to occur via accident or random chance.
By some measures, a majority of English Shepherd sire lines could be considered rare because the breed population dipped so low in the late 20th century that there aren’t a LOT of dogs in any line. Please keep that context in mind! Highlighting particular dogs/lines that are in immediate need of support does not mean that lines/dogs not named are “safe”. It simply means that they are relatively more secure than the ones identified as rare. The goal is to maximize the healthy genetic diversity derived from all available lines in the breed, both those that are rare and those that are well-represented.
So, what is “rare”? For this report, the threshold for designating a line as “rare” is set at fewer than 10 active sires or dams identified in the 6-year interval spanning 2013 – 2018. This list is by no means exhaustive, there may be lines not included that are in similarly precarious condition, this is simply the list that can be identified from available public data. It is also helpful to note individual branches within some of the genetically “secure” lines that are in danger of being lost because there are few active sires/dams in that branch of the line. In other words, if an ancestral line is well represented because there was one very prominent sire or dam, offspring from that particular dog may be plentiful; but if that prominent dog had a relative who had very few offspring, those dogs – while the same sire/dam line – are an endangered source of diversity within that line. This report does not include all the detail on each line so please take this as a starting point and spend time investigating where your dog fits within their family line.
One last note: dogs that were recently stepped in to the registry are a special category. Those lines are expected to have few descendants listed in the registry. Nonetheless, they deserve to be included because unregistered lines are vulnerable to being lost over time and provide a potential source of genetic diversity.
The tables below provide a complete list of the sire and dam line founders identified in this study. Please contact ESBC if you have questions or information that will help expand our understanding of the breed population.
Rare Sire Lines:
- Peck’s King
- Show’s Lobo
- Shep (behind Rea’s Boone)
- King (behind Abe)
- McIntyre’s Tony
- Lewis’ Chip
- Bilbrey’s Major
- Schoeman’s Dog
- Emanuel’s Butch
- Old Shep (behind Oney’s Butch)
Rare Dam Lines
- Davidson’s Carrus Ranch Chalsey
- Ginny
- Stegall’s Queen
- Rogers’ Mickey
- Smucker’s Aunts Hills Sandie
- Shows’ Kate
- Brown’s (Anderson’s) Twinkle
- Rogers’ Cindy
- Partlow’s Tippy
- Semy Williams Kate
- Spunky
- Queen Duchess
- Trudy Wren
- Blankenship’s Babs
- Carr’s Goldie
SUMMARY TABLE:
Sire Line Founders, 2013 – 2018
The table to the right summarizes information on Sire Line founders for English Shepherd litters registered in the 6 year interval spanning 2013 – 2018. The far left column identifies the sire line founder, the middle column identifies key descendants connecting that founder to the present generation, the names in the right column are recent sires descending from that line. The numbers under #S heading are the number of different stud dogs from that line who sired a litter during the interval. The numbers under the #L heading are the number of litters produced during the interval from the line.
Some founders are represented only through a single line of dogs; when that is the case the information is presented in one row. Some founders can be found by tracing present generation dogs back through different descendants branching off the family tree from the original founder; when that is the case, there may be several rows associated with a single founder.
The English Shepherd Breed Conservancy is dedicated to studying breed health and genetics, and in particular genetic diversity. We would love to have your assistance in better identifying the various potential sources of genetic diversity within the breed. Please contact us if you have questions, if you have a dog whose unique ancestry is not reflected here, or if you would like to volunteer to assist with additional research projects.
SUMMARY TABLE:
Dam Line Founders, 2013 – 2018
The table to the right summarizes information on Dam Line founders for English Shepherd litters registered in the 6-year interval spanning 2013 – 2018. The far left column identifies the dam line founder, the second column identifies key descendants connecting that founder to the present generation. The numbers under #D heading are the number of different dams from that line who produced a litter during the interval. The numbers under the #L heading are the number of litters produced during the interval from the line.
As noted above, the English Shepherd Breed Conservancy is dedicated to studying breed health and genetics, and in particular genetic diversity. We would love to have your assistance in better identifying the various potential sources of genetic diversity within the breed. Please contact us if you have questions, if you have a dog whose unique ancestry is not reflected here, or if you would like to volunteer to assist with additional research projects.
Not Listed Here?
Do you have an English Shepherd from ancestral lines not represented in these tables ?
