The Yellowstone bison population currently exists as an isolated "metapopulation." This is what population geneticists call a large population which consists of several smaller groups called "subpopulations" which interact with each other to some degree. Each subpopulation within the metapopulation can have itís own distinctive genetic structure which distinguishes it from the others. If individuals remain in their own respective subpopulation and do not mate with outside individuals, certain genes within the subpopulation become fixed. In other words there is a loss of alternative genes through random mating and selection. This eventually leads to a loss of genetic variation in the subpopulation. If there is migration and mating of individuals at a moderate rate between the subpopulations, then genetic variation can be maintained throughout the entire metapopulation.

Genetic variation is critical to the long term survival and evolutionary potential for any species or population. It can become decreased through isolation, inbreeding, and strong selective pressures such as environmental changes, diseases, or extensive mortality. Loss of genetic variabilty removes genes from the population that could enable certain individuals to survive a major event, reproduce, and pass on their genetic material to the next generation. Low genetic variability within an individual or population greatly reduces the ability to respond to a major disease event or adapt to changing environmental conditions. Ultimately this will drive them into an extinction vortex from which they might not recover. This has already occurred in many species who have disappeared from the globe.

The current "clear cut" style of removing bison from the Gardiner area poses a grave risk to the genetic integrity of the entire Yellowstone bison herd for a number of reasons. The really tragic part of this is that the subpopulation (northern herd) was nearly wiped out in 96/97. The current herd probably consists of remnant individuals and migrants from other adjacent subpopulations. Removal of a large number of individuals from only one subpopulation within a single region poses the risk of permanent loss of entire lineages, which could be irreplaceable.

If population control were truly necessary, then perhaps a scattered, random removal of individuals would be more conducive to maintaining genetic diversity. However, the carrying capacity for bison in the Greater Yellowstone ecosystem has not been accurately established.

Therefore the current population cap of 3000 is rather arbitrary and not representative of what the ecosystem can actually support. If the efficiency of bison grazing patterns and their remarkable ability to extract the most nutrition from the lowest quality forage is considered in conjunction with potential availability of public lands, this number should be much higher.

The cumulative effects of yearly removals of entire large groups of bison within an isolated population will certainly result in a steady erosion of the genetic integrity within this herd. This would be a national tragedy and will ultimately result in the demise of this valuable herd!

We must urge our public officials to discontinue the slaughter of Yellowstoneís bison in this manner. We cannot allow another repeat of the winter nightmare of 1996/97. It is key to the survival of this herd for future generations that this current removal operation is immediately put to an end. Prevention of any further herd reductions will ultimately contribute to the conservation of this herd and augment global biodiversity.

See News Article 4/24/02- Substantial portion of remaining 'pure' bison in Yellowstone
By SCOTT McMILLION Chronicle Staff Writer

Genetically, Bison Don't Measure Up to Frontier Ancestors- April 2002 By MARK DERR (NYT) ABSTRACT - Genetic study led by Texas A&M geneticist Dr James Derr finds that more than 90 percent of private bison and many animals in publicly owned herds are actually bison-cow hybrids; finding reduces pool of pure bison available for preserving species to fewer than 15,000 animals (Word Document, 4 pages)