In North America, the male lines of Northern Dancer and Mr. Prospector have been dominant both on the racetrack and in the sale ring for several decades, and both are in the process of paring down to a few strong branches---a process hastened in Mr. Prospector's case by his great prowess as a broodmare sire and the fact that many of his good sons have also proven fine sires of broodmares. Ironically, this is actually strengthening Mr. Prospector's position as a great genetic influence on the breed, as inbreeding to him through both male and female sources is becoming quite commonplace among top-quality stock. In the meantime, however, another sire line is rising to a dominant position that might have seemed unthinkable a decade ago---that of A.P. Indy, who 10 years ago took the second of his two American sire championships. He is now pensioned, but he has five sons and two grandsons among the top 20 American general sires as of today.
A look at Saturday's racing results serves to illustrate the impact that A.P. Indy's male line is having. His grandson Tapit, currently well on his way to a third consecutive title as America's champion sire. is the sire of the dead-heat winners of the Spinaway Stakes (USA-I), Pretty City Dancer and Sweet Loretta, as well as Woodward Stakes (USA-I) third Frosted, already a multiple Grade I winner this year. The Spinaway third-place runner Cherry Lodge? She's by A.P. Indy's son Bernardini. Pulpit, the sire of Tapit and paternal grandsire of California Chrome, is also the sire of Miss Chatelaine, third in the Glens Falls Stakes (USA-IIIT). A. P. Indy's daughter Secret Someone won the Kentucky Downs Ladies Turf Stakes (USA-LT), and A.P. Indy's son Malibu Moon sired La Lorgnette Stakes (CAN-L) winner Moonlit Promise. That's quite a good showing just for one Saturday's graded and listed stakes.
Ironically A. P. Indy's sire line is getting a lot of help from Mr. Prospector, who is the broodmare sire of A.P. Indy's important sons Pulpit, Malibu Moon, Mineshaft, Congrats and Flatter and is the male-line ancestor of the broodmare sires of Tapit and Bernardini through his son Fappiano. This is contributing to an ever-greater divergence between American and European bloodlines, as both the Mr. Prospectors and the A.P. Indys have as a group been extremely effective on dirt but not so much on turf (though the Machiavellian and Kingmambo branches of Mr. Prospector are important exceptions), and I expect to see this divergence extend to Argentina (where dirt racing is a major part of the calendar, and where the Mr. Prospector line has already enjoyed great success) and Brazil (where most of the prestige events continue to be contested on turf). Northern Dancer isn't going away anytime soon, of course, but a similar dirt/turf split is evident between those lines that have been highly successful in North America and those predominant in Europe.
It will be interesting to watch the evolution of the A.P. Indy male line over the next couple of decades as the slew of high-class grandsons and great-grandsons of the old monarch take their turns in the breeding shed. Most likely, the line will pare down to one or two major branches as another male line begins its run at the top, but not before A.P. Indy joins that handful of great progenitors whose names are so widely dispersed in pedigrees that they are all but universal in American breeding.