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,,<< . The bottom line is that the use of "F" alleles at any/all of the six loci discussed above to designate recent hybridization events and recent gene flow from flannelmouth to razorback populations is not warranted from the data now available. It is possible, even likely, that based on the analyses of razorback populations from the Upper Colorado and other populations reported in this study, that the two species share F (and R) alleles. As the authors pointed out in their 1987 paper, it is possible that a common ancestor to both taxa had both alleles. Another possibility is that shared alleles are the result of past (perhaps ancient) hybridization events. The real issue is m the Etter Pond fish and the other Upper Colorado River fish share some alleles with flannelmouth suckers? Dr. Buth's conclusion is that this sharing comes from some ~ hybridization event. We feel that it is more likely that the Upper Colorado River razorback population shares alleles with tlannelmouth suckers as a result of non-recent, perhaps very ancient, events. Interspecific hybridization is a fairiy widespread mechanism by which fishes "capture" new genetic material and must certainly be considered one of many "normal" evolutionary processes. The original Etter Pond parental individuals, as well as the others collected from the Upper Colorado River mainstem, were adult fish and, therefore, it is unlikely that they represent a single family group. These limited data indicate that the entire Upper Colorado River population likely carries "flannelmouth" alleles at a number of genes as a result of one or more events. These events may even occur fairly continually (although relatively rarely) throughout history. One might speculate that "flannelmouth" alleles may in fact, provide the Upper Colorado River population with some critical local adaptive advantage over fish from the lower basin. That is, rather than being some undesirable "pollution" of the razorback genome resulting from some abberrant recent event, the presence of the "F' alleles, may represent a process by which Upper Colorado River razorback suckers diverged from other stocks and adapted to the environmental conditions found in that habitat. Let us reiterate here, that this discussion has be~n entirely speculative. The potential use and distribution of the Etter Pond fish, however, must be assessed from another standpoint Based on the genotypes reported for the four loci among the 55 Etter Pond individuals, we feel that the most likely explanation is that a single female with the following genotype, Ck-A = FF; mIcdh-A = RR; mMdh-A I = RR; Ada-A2 = RR; spawned with a number of males (minimum of 2, but based on genotype frequencies at the various loci, more likely 3-5), and that those individual males likely experienced differential mating success. As a result, the common cohort in Etter Pond most likely represents the genetic contribution of only a very few fish. Without furthr analysis of either more Etter Pond fish or their offspring, care should be taken in any proposal for their use in artificial propagation programs or for use in radio-tracking studies. Conservative approaches (e.g., use of only one sex in tracking studies) is indicated. Our recommendation is that the Etter Pond fish and their offspring should not be destroyed based on the evidence provided by Dr. Buth. Further genetic analysis of a few of the offspring at additional loci should shed some additional light on the possibility of a recent hybridizational event. Finally, we would like to urge the Biology CoI11IIl.ittee to seek more timely advice/review from the Genetics Panel. We did not receive the Buth report until five days before the Salt Lake City meeting and had no sense of the urgency involved. We have learned that destruction of the fish in question came very close to happening; that would have been a tragedy. We would like to close by adding that we recognize the importance (and enormity) of the job at hand; we are happy to contribute wherever we can and will try to the best of our abilities to react in a time frame that is of use to you and the Program in general.