Inbreeding avoidance among spawning adults
We tested for the presence of inbreeding avoidance among adult Yellowstone Cutthroat Trout to understand whether there are mechanisms that prevent breeding among related individuals. To do this, we first evaluated the accuracy of four different relatedness estimators (Queller & Goodnight 1989; Li et al. 1993; Lynch & Ritland 1999; and Wang 2002) based on correlation coefficients between observed and expected values. We employed the ‘compareestimators’ function in the relatedpackage in R (Pew et al. 2015; R Core Team 2020) which used observed allele frequencies within our focal population to simulate 1,000 individuals of known relatedness and selected the estimator with the highest correlation coefficient between known and estimated relationships. Next, we used outputs from parentage analysis to identify two subsets of the adult population, adults that were responsible for producing progeny and those that were not. We then calculated average within-group relatedness using the best-fit relatedness estimator for these two groups and compared against expected values using the ‘grouprel’ function within the related package. Briefly, expected values were generated by randomly shuffling individuals between groups (which were kept at a constant size), and then relatedness was calculating within these newly constructed groups. We performed a total of 100 simulations and p -values were estimated as the number of simulations out of the total number ran that were less than or equal to our observed value.