The distribution of non-native markers may not be randomly distributed among the fish 

 in a sample primarily because hybridization has only recently begun in the population, 

 the sample contains individuals from two or more genetically divergent populations, or 

 both. Such collections can be analyzed at the individual level only. Since such samples 

 do not come from hybrid swarms, the proportion of native and non-native markers cannot 

 reliably be estimated. In these cases, the sample may contain some non-hybridized 

 individuals. Rather than reporting percent genetic contributions we report the number of 

 individuals in the sample, based on the fragments they possessed that may be non- 

 hybridized. 



Literature Cited: 



Boecklen WJ, and Howard DJ (1997) Genetic analysis of hybrid zones: numbers of 

 markers and power of resolution. Ecology 78 (8) pp. 261 1-2616. 



Sample Details: 



Silver Creek: (longitudinal sample) All individuals in this sample exhibited fragments 

 diagnostic of westslope cutthroat trout (Oncorhynchus clarki lewisi). However, three 

 individuals from Section 1 also displayed diagnostic rainbow trout markers (O. mykiss). 

 The individuals that appeared hybrid were all post-Fl hybrids, indicating that 

 hybridization has been occurring for generations. Assuming random mating proportions, 

 the genetic contribution of westslope cutthroat trout and rainbow trout at Site I is 93% 

 and 7%, respectively. Samples taken from Sites 2 and 3 showed no evidence of 

 hybridization. Assuming random mating proportions, genetic contributions of westslope 

 cutthroat trout and rainbow trout averaged over all three sampling sites is 98% and 2%, 

 respectively. 



Deer Creek: (longitudinal sample) AH 12 successfully amplified individuals in this 

 sample exhibited only fragments diagnostic of westslope cutthroat trout. With a sample 

 size of 12, we have only a 62% chance of detecting as little as 1% hybridization between 

 westslope cutthroat trout and rainbow trout using four PENE markers. Although we 

 found no evidence of introgression, our confidence in our ability to detect introgression 

 with rainbow trout is lower than if we had a full sample to analyze. Until further data 

 indicate otherwise, the conservative approach would be to manage this as a pure 

 westslope cutthroat trout population. 



Siegel Creek: All 18 successfully amplified individuals in this sample exhibited only 

 fragments diagnostic of westslope cutthroat trout. With a sample size of 18, we have an 

 89% chance of detecting as little as 1% hybridization between westslope cutthroat trout 

 and rainbow trout using six PINE markers. Although we found no evidence of 

 introgression, our confidence in our ability to detect introgression with rainbow trout is 

 lower than if we had a full sample to analyze. Until further data indicate otherwise, the 



