3.2 Spatial Analysis
The appearance of among-population genetic variation can be influenced by isolation by distance, in which geographically proximate populations are more closely related. Isolation by distance can also affect the appearance of genotypic correlations because data from different populations is not independent. We therefore tested first for evidence of spatial autocorrelation. Spatial autocorrelation was significant among the populations both for the mean values of the circadian period and the range of family values within each population. Clustering of populations was limited to two specific “hot spots,” and these accounted for the autocorrelation. First, two populations located at highest elevation within the Snowy Range (Libby Flats (LIB) and Lewis Lake (LEW)) had similar values for circadian period. Second, the three easternmost populations, located in the Laramie Range of SE Wyoming (populations Crow Creek (CRW), Happy Jack Trail (HJT), and Middle Crow Creek (MCC)), had similar values for population mean and within-population range. Outside of these two clusters, values were randomly spaced across the populations. Further results are presented as observed and after adjusting for the occurrence of spatial autocorrelation.