Native Dancer at the Vanishing Point
by Roger Lyons
Native Dancer has reached a genetic vanishing point in the sense that his influence is so pervasive that his contribution can no longer be contrasted in any significant way with the mainstream of the population. This is evident from the table accompanying my last post, which shows that in no instance do the strike rates of US stallions with mares in some descent of Native Dancer exceed their overall records. That is, no “contemporary” US stallion has a statistically measurable preference for mares in descent of Native Dancer. Keep in mind, though, that it’s because the broodmare population is so largely defined by Native Dancer. It’s like the air they breathe.
Moreover, only two stallions–Diesis and Dixieland Band–(that the table rather loosely defines as contemporary) fall below their normal strike rates when crossed with mares in some descent of Native Dancer, and they are both deceased. They were bred quite differently from one another with respect to Native Dancer–Diesis, by Sharpen Up, by Atan, by Native Dancer, and Dixieland Band, by Northern Dancer, out of Natalma, by Native Dancer.
Reasons can no doubt be given for why they had trouble with mares in descent of Native Dancer, but the fact that they did so has always had more practical import than the reasons why. More interesting here is that their aversion to mares in descent of Native Dancer and their shared birth year of 1980 renders their stud records especially useful as measures of the proliferation of Native Dancer’s influence.
Consider what it could mean that both of these stallions had significantly higher strike rates with mares born prior to 1985 than with mares born after that year.
Dixieland Band got superior runners from 50 of 435 individual mares born prior to 1985, for 11.5%; but, of the 644 mares born after 1984, 51 produced superior runners by him, for only 7.9%. Furthermore, only 23 of the 396 mares born after 1989 produced superior runners by him, for only 5.8%. As Native Dancer’s influence spread throughout the later population cohorts, Dixieland Band’s strike rate with those mares declined. Of the 219 mares with Northern Dancer in their ancestries, only 10 produced a superior runner, and he was barely in range of his average with mares in descent of Mr. Prospector.
Diesis’ stud record reflects the same broad pattern. While 48 of 343 mares born prior to 1985 produced superior runners by him, or 14%, only 28 of 453 (6.2%) born after 1984 did so. Of the 277 mares born after 1989, only 10 (3.6%) produced superior runners by him. Diesis got a superior runner from only one of 64 mares with Mr. Prospector in their ancestries, and he was barely in range of his average with mares in descent of Northern Dancer.
With each successive broodmare population cohort, in which crosses of Northern Dancer and Mr. Prospector assured a rapid accumulation of Native Dancer influence, the strike rates of Dixieland Band and Diesis declined. It seems warrantable to conclude that Native Dancer’s proliferation in the broodmare population had a more profound effect on their stud records than could possibly be attributed to a decline in viability due to increasing age.
This idea of a stallion working with mares of a certain generation or era and not with others is fascinating, with lots of implications. If one can believe the face of the mare population can change in some not so extended period of time. We already note stallions that work with a given geographic population better than others. . .
February 26th, 2011 at 2:57 pmGreg, your analogy makes perfect sense to me–that, if a stallion works better in one geographic region than another, then it’s conceivable that a stallion might work with better with broodmare population cohorts separated significantly by birth year. That is exactly what the numbers suggest.
February 26th, 2011 at 6:12 pm