COI: How Many Generations are Enough?

In her published paper, A Genealogical Survey of Australian Registered Dog Breeds, Claire Wade would have you believe that looking at 4.1 generations of Toller data is enough to get a good idea of what the level of inbreeding is in the breed. I went ahead and looked at ALL the pedigree data available for her own dog, “Burn,” so we can decide if looking at just 4 generations tells us the true story of what’s going on with this dog’s inbreeding.

This is a chart of what I found as I looked at Burn’s COI from 1 Generation all the way up to 12 generations.

Claire Wade's NSDTR "Burn" has a COI of nearly 30%.

Claire Wade's NSDTR "Burn" has a COI of nearly 30%. If you're a fool you might pretend it's lower than that by looking at only a few generations.

COI is a measure of inbreeding in an individual and it’s almost always denoted with the number of generations that are being looked at in the calculation.  For example, a COI5 or COI(5) is looking at 5 ancestor generations and only calculating the inbreeding that is seen within those dogs.  It ignores consanguinity of any dogs further back in the pedigree for the sake of calculation simplicity.  A COI of rank N is intentionally blinded to all dogs in generations N+1 and beyond.  Some pedigree software packages treat generation 1 differently, so it’s wise to confirm just how many dogs are being looked at if you’d like to compare COIs calculated by different software packages (some count the individual as generation 1, others count the parents as generation 1).

Why would someone want to intentionally blind themselves to more information?  First, the COI calculation is not trivial and doing it by hand is time consuming and arduous for most people.  Second, the calculation requires extensive pedigree information that is not always available for many generations.  Third, looking at lower N COIs will measure recent inbreeding versus deeper inbreeding.

Am, NSDTRC-US CH Edlyn Seastar Dodge N Burn WC CGC CCD JD "Burn"

Am, NSDTRC-US CH Edlyn Seastar Dodge N Burn WC CGC CCD JD "Burn" A Nova Scotia Duck Trolling Retriever owned by biologist Claire Wade.

But let’s not fool ourselves that lower N COIs are better or more accurate or that higher N COIs are trivial.  COI calculations are meant to predict the level of homozygosity (doubled up alleles) in an individual due to the same ancestors showing up multiple places in the pedigree.  No matter how many generations you look at, the dog’s pedigree and ancestry doesn’t change.  Consanguinity has created a certain level of doubling up on alleles in the dog and that will not change if you blind yourself to more distant generations.  The more generations you look at, the closer your calculation will approximate the real level of inbreeding present in your dog.  That’s why a COI calculation of N+1 is in general always superior to COI(N).  More information is always equal to or better than less information.

In practice though, we run across both pedigree collapse and a limit to how far back our knowledge extends.  Once we start hitting founder dogs, going back any further generations on those dogs won’t actually give us more information because that information is lost or unknown.  If the oldest known ancestor is at most 10 generations back from our current dog, taking a COI(15) won’t really tell us anything that a COI(11) will.  But how do we know when our COIs are giving us diminishing returns?  Well, we can keep taking higher N COIs until they stop changing much.  They might stop changing because we’ve taken into account all known inbreeding or they might stop changing because we’ve run out of useful information, or both.

To illustrate this, I’ve graphed Claire Wade’s pet Toller Burn’s COI over N generations from N=1 to N=12.  You can see this chart at the top of the post.  Notice how as we look at more generations the COI quickly rises and it doesn’t start to stall until the 10th generation and we don’t see significant change only two generations after that.  If you asked me what this dog’s COI was, I’d say at least 28%.  There’s really no reason to look at fewer generations as none of those numbers would tell you anything of value.

A pedigree chart of Claire Wade's Toller "Burn" showing pedigree collapse

A pedigree chart of Claire Wade's Toller "Burn" showing pedigree collapse

Now if we look at Burn’s graphic pedigree again, we can see why the COI peters out at 12ish generations: there’s really no more information after that point which can move the COI significantly.  Every dog on Burn’s complete pedigree can be traced back to Burn in 11 generations or less.  In the following chart, the “Min Gen” column shows the first generation a given ancestor shows up in and the Max Gen shows the last generation they show up in.  Count records how many times they show up in the pedigree total.  As you can see, all the ancestors show up in 11 generations or less as 11 is the largest number in the Min Gen column.

Toller Name COI Count Min Gen Max Gen
Edlyn Seastar Dodge N Burn 28.245% 1 0 0
Fionavar Javahill Topgun 25.5433% 1 1 1
Edlyn’s Picture Perfect 30.4383% 1 1 1
Berdia True Blue to Kirchoff 22.5485% 1 2 2
Edlyn’s Just In Thyme 28.0725% 1 2 2
Landew KD’s Prince of Tides 29.5426% 1 2 2
Renarder’s Regina Reverenca 22.9474% 1 2 2
Harbourlights Salty Dog 24.4761% 1 3 3
Westerlea Coast’l Tradewinds 21.8847% 1 3 3
Lonetree G’s Parklake Sailor 34.9038% 1 3 3
Fairchilds Nikita 19.9141% 1 3 3
Westerlea’s Canadian Rockies 28.9524% 1 3 3
Landew’s Cinnamon Star 25.136% 1 3 3
Edlyn Secondchance at Roslyn 31.314% 1 3 3
Westerlea Superstar At Berdia 29.7271% 1 3 3
Harbourlights Big Splash 28.7842% 1 4 4
Landew’s Blue Boar Inn 31.8234% 1 4 4
Springvale’s Roy’ll Flush 32.2447% 1 4 4
Harbourlights Im Just Ducky 24.3835% 1 4 4
Sagewood Copper Prospector 29.6278% 1 4 4
Danbury’s Southern Fancy 30.2959% 1 4 4
Westerlea’s Fine and Dandy 32.9486% 1 4 4
Landew’s Cinnamon Delight 23.9786% 1 4 4
Drogstas Mio Pa Fairchilds 23.1443% 1 4 4
Ricky 32.0734% 1 4 4
Sagewood’s Lonetree Auburn 34.982% 1 4 4
Benili’s Ghats 21.56% 1 4 4
Westerlea’s Jane Eyre 28.9524% 1 4 4
Boo-Evil of Harbourlights 24.5239% 1 5 5
Glenmaurs Casey of Elias 23.9786% 2 4 5
Cinnstar’s Johnny Walker Red 23.0059% 1 5 5
Aspen Gold’s Southern Rose 31.5823% 1 5 5
Jalna’s Zealous Zephyr 28.0798% 1 5 5
Cinnstar’s Westerlea Redhead 28.4433% 1 5 5
Westerlea’s Echo of Shelley 43.612% 2 4 5
Westerlea’s Digby Schooner 18.812% 3 4 5
Sagewood’s Silver Shadow 34.982% 1 5 5
Ravtassens Micmac 24.3446% 1 5 5
Riverduck of Drogsta 24.3835% 2 5 5
Flyingtollers Ronja 27.5743% 1 5 5
Drogstas Pomperipossa 23.0251% 1 5 5
Jalna’s Candida Daniell 30.443% 1 5 5
Dobirstein’s Golden Dazzle 21.3002% 1 5 5
Westerlea’s Sagewood Admiral 35.4466% 1 5 5
Spike of Harbourlights 29.3945% 1 6 6
Harbourlights Rip Tide 22.0001% 3 5 6
Westerlea’s Mountain Echo 32.4885% 2 5 6
Westerlea’s Sprig of Holly 35.4466% 3 5 6
Cinnstar’s Ian of Little River 28.4433% 1 6 6
Cinnstar’s Western Ptarmigan 31.8391% 1 6 6
Westerlea’s Audacious Wave 39.0105% 2 5 6
Westerlea’s Tippy Micmac 35.4466% 1 6 6
Harbourlights Nedgewick 26.7151% 1 6 6
Birdcherrys Nova 25.762% 1 6 6
Harbourlights Perky Peppy 27.4994% 1 6 6
Westerlea’s Golden Glory 24.6086% 1 6 6
Chin-Peek Golden Sheeba 42.1631% 1 6 6
Jalna’s Gentle Giant 25.4484% 1 6 6
Jalna’s Tia The Teal Tracker 25.8635% 1 6 6
Jalna’s Fire Fox 33.2932% 1 6 6
Jalna’s Onolee Over The Ocean 19.3871% 1 6 6
Jalna’s Personality Plus 15.5945% 1 6 6
Harbourlights Laddie Buck 26.7151% 2 6 6
Harbourlights Misty Blue 17.6758% 1 6 6
Harbourlights Foxy Amber 21.7468% 3 5 6
Chin-Peek Kitt’s Barney 42.1631% 3 5 6
Harbourlights Foxy Tawny 22.8516% 7 5 7
Harbourlights Mighty Mike 11.7188% 3 6 7
Sandycove At Westerlea 35.7401% 3 5 7
Harbourlights Fundy Pal 18.457% 3 7 7
Harbourlights Fundy Gal 19.9219% 1 7 7
Harbourlight’s Village Sire 15.625% 1 7 7
Westerlea’s Bonny Bluenose 28.599% 10 5 7
Harbourlights Nova Nipper 29.3945% 1 7 7
Hilan Lad of Harbourlights 22.3022% 1 7 7
Sandycove’s Gold Horizon 35.7401% 5 5 7
Harbourlights Ala Gatter 13.0859% 3 6 7
Solidaire of Jeffery Coldwell 20.047% 2 6 7
Westerlea’s Cinnamon Teal 21.3737% 3 6 7
Chin-Peek Kel’s Happy Toby 16.748% 4 6 7
Jalna’s Oneka The One N Only 19.3871% 1 7 7
Liscot’s Turn The Page 25.4517% 1 7 7
Wabanaki’s Village Vixen 21.3257% 3 6 7
Jennella’s Breton MacNamuir 25.4517% 2 6 7
Jalna’s Quillo Quest 15.5945% 1 7 7
Westerlea’s Vital Spark 35.7401% 2 6 7
Westerlea’s Flying Fox 21.3737% 2 6 7
Westerlea’s Voyager of Jalna 21.3737% 1 7 7
Jalna’s Eager Boots 37.915% 1 7 7
Jalna’s Legendary Love 15.5945% 2 7 7
Jalna’s Brazen Brat 19.3871% 2 6 7
Harbourlights Fundy Star 12.5% 2 7 8
Harbourlights Tilly The Toller 11.7188% 1 8 8
Harbourlights Miss Molly 22.8516% 3 7 8
Harbourlight’s Golden Tammie 19.9219% 2 7 8
Westerlea’s Coast To Coast 29.1992% 11 6 8
Harbourlights Red Kali 27.9297% 6 7 8
Jalna’s Elegance In Red 37.915% 1 8 8
Tahgahjute of Jeffery Coldwell 11.8164% 2 7 8
Chin-Peek Kel’s Kitty 35.1563% 8 6 8
Westerlea’s Summer Sunset 21.3737% 10 6 8
Westerlea’s First Lieutenant 24.6586% 12 6 8
Sproul’s Earl of Jalna 18.3594% 4 7 8
Jalna’s Enchanted Red Ember 37.915% 2 8 8
Jalna’s Red Emperor 37.915% 5 7 8
Sproul’s Jennifer Jalna 22.4976% 4 7 8
Westerlea’s Tru Ray Red Rebel 21.3737% 3 7 8
Liscot’s Crown Jewel 26.0345% 1 8 8
Liscot’s Scotia O’ The Glen 26.0345% 2 7 8
Alexander of Schubendorf 25% 3 8 8
Harbourlights Village Sire 15.625% 16 6 9
Harbourlights Scotia Boy 12.3047% 10 5 9
Westerlea’s Spring Melody 21.3562% 12 7 9
Green Meadows Buttons & Bows 15.625% 2 8 9
Marlynbar Chukie 27.3926% 2 8 9
Contessa of Jeffery Coldwell 23.6328% 9 8 9
Sproul’s Lady MacGregor 21.6797% 4 8 9
Sproul’s Tantramar Toby 17.6514% 4 8 9
Chin-Peek Tamie 20.3125% 8 7 9
Harbourlights Fundy Bell 12.5% 11 6 9
Harbourlight’s Forever Amber 19.9219% 6 8 9
Westerlea’s Copper Vixen 21.3737% 13 5 9
Sproul’s Angus MacBeth 16.6748% 3 8 9
Schubendorf’s Mandy 0% 3 9 9
Harbourlight’s Happy Hooker 19.9219% 4 7 9
Liscot’s Foxy Lady 30.4688% 3 8 9
Westerlea’s Windsor Lad 18.8889% 12 7 9
Harbourlights Foxy Nisku 0% 10 6 10
Marlynbar Chick 24.6094% 2 9 10
Westerlea’s Scotian Gold 23.1201% 12 8 10
Sproul’s Merry Dancer 14.0625% 4 9 10
Sproul’s Kinsman’s Cedar Fox 16.6748% 12 8 10
Sproul’s Argyle Angel 35.9375% 3 9 10
Westerlea’s White Ensign 27.3926% 48 6 10
Sundrummers Seawitch 25.3601% 42 6 10
Green Meadows Candy Kisses 15.625% 10 8 10
Sproul’s Highland Commander 35.9375% 54 7 11
Sproul’s Tawnee Princess 16.4063% 19 9 11
Shelburne of Jeffery Coldwell 11.6211% 60 7 11
Sproul’s Highland Lassie 22.8516% 42 7 11
Chin-Peek Majour Tyrol 18.75% 2 10 11
Chin-Peek Fancy Red 20.3125% 2 10 11
Crusader of Jeffery Coldwell 32.6416% 59 7 11
Bellboy of Jeffery Coldwell 24.5605% 12 9 11
Alexander MacTavish 12.5% 20 8 11
Sandy MacGregor of Sproul 14.0625% 68 7 12
Danny Boy of Harbour Lights 15.625% 75 7 12
Schubendorf’s Kellie 0% 18 7 12
Bo Diddley of Jeffery Coldwell 35.9375% 62 8 12
Mary Anne of Harbour Lights 0% 23 8 12
Rapunzel of Jeffery Coldwell 26.3672% 59 8 12
Happy Holly of Harbour Lights 12.5% 42 8 12
Chin-Peek Sue Buff 0% 10 8 12
Robie Surf of Glencoe 18.75% 87 7 13
Buff Coldwell of Jeffery 18.75% 62 9 13
Nick’s Foxy Snooper 15.625% 75 7 13
Harbour Lights Autumn Fancy 15.625% 129 8 13
Red Rock Star 0% 72 8 13
Chin-Peek Sandy 25% 10 9 13
Rusty Jeffery of Kemptville 18.75% 62 9 13
Jeffery of Port Williams 23.6328% 119 8 13
Chin-Peek Wee Lady Susan 18.75% 71 9 13
Joggins Foxy Duke 0% 87 8 14
Blond Wokwis of Golden Tessy 12.5% 87 8 14
Tusket Isle Heatherton 12.5% 124 10 14
Schubendorf’s Kitty 0% 73 10 14
Red Russel of Jeffery 15.625% 199 8 14
Florette Jeffery of Overton 40.625% 128 9 14
Chin-Peek Golden Lucky Kim 0% 285 6 15
Green Meadows Golden Tessy 0% 87 9 15
Chin-Peek Star’s Lady 25% 199 7 15
Betty of Schubendorf 25% 507 7 15
Green Meadows Scot of Acadie 0% 124 11 15
Green Meadows Molly of Acadie 0% 124 11 15
Chin-Peek Chip Bar-Mar Car 31.25% 130 9 15
Green Meadows Lac-a-Pac Pal 0% 477 7 15
Green Meadows Tawnee Wakon 0% 601 8 16
Chin-Peek Lim-bo 25% 209 8 16
Chin-Peek Lady Susan 0% 258 10 16
Chin-Peek Golden Star 25% 209 8 16
Chin-Peek Lucky 25% 285 7 16
Pat of Schubendorf 25% 756 7 17
Chin-Peek Golden Belle 0% 209 9 17
Chin-Peek Ginger Julie 25% 543 8 17
Chin-Peek Shep 0% 494 8 17
Schubendorf’s Sandy 0% 1432 8 18
Chin-Peek Golden Taffie 25% 543 9 18
Chin-Peek Golden Kim 0% 752 9 18
Schubendorf’s Lady 0% 756 8 18
Majour of Schubendorf 0% 2789 8 19
Chin-Peek Lassy 0% 752 9 19
Goldie of Schubendorf 0% 2695 8 19
Digger 0% 2789 9 20
Bidewell’s Flip 0% 2750 9 20
Bidewell’s Lady 0% 2207 9 20
Lassie A 0% 2789 9 20
Gem of Green Meadows 0% 3594 9 20
Autumn’s Cinderella 0% 3594 9 20
Bobo 0% 2789 10 21
Buffy 0% 3594 10 21
Buster 0% 2750 10 21
Butch 0% 2207 10 21
Sandy 0% 2207 10 21
Tootsie 0% 2750 10 21
Flash 0% 3594 10 21
Dilly 0% 3594 10 21
Teddy 0% 3594 10 21
Quinnie 0% 2789 10 21
Sassie 0% 2789 10 21
Gunner 0% 3594 11 22
Star 0% 3594 11 22
Judy 0% 3594 11 22
Laddy 0% 3594 11 22
Flossy 0% 3594 11 22
Sally 0% 3594 11 22

While there’s certainly information after the 12th generation, we aren’t adding any new names to the pedigree after that point, just connections between them. Each generation after we’d need to see twice the level of inbreeding just to begin to make a difference on the COI given that there are theoretically twice as many possible breedings each level. Seeing as most paths going back are already dead ends, there’s no way we can keep that up. The few lines that go to 20 generations or more are likely to have already contributed to for/against the COI in a significant way already.

In her published paper, Claire Wade would have you believe that looking at 4.1 generations of Toller data is enough. What do you think now that you’ve seen the whole truth?

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About Christopher

Christopher Landauer is a fifth generation Colorado native and second generation Border Collie enthusiast. Border Collies have been the Landauer family dogs since the 1960s and Christopher got his first one as a toddler. He began his own modest breeding program with the purchase of Dublin and Celeste in 2006 and currently shares his home with their children Mercury and Gemma as well. His interest in genetics began in AP Chemistry and AP Biology and was honed at Stanford University.