F2 hybrid crosses differ in their deviations from null expectations but exhibit similar average trait values.
The results of Bayesian model suggest that there is no difference in average trait values between Crescent Pond (mean trait value: -0.00096, 95% HDI: -0.0044, 0.0023) and Little Lake (mean trait value: 0.00032, 95% HDI: -0.0040, 0.0050) F2 hybrids. Estimates of 95% HDI for each of the 18 traits confirmed that there were no significant differences between F2 populations (Appendix Table E4). Despite the lack of differentiation in trait values between these two populations, we found significantly different patterns of deviation from our null expectations between Crescent Pond and Little Lake. For example, the estimates for 16 of the 18 craniofacial traits in Little Lake met the assumptions of additivity, while only 7 of the 18 traits in Crescent Pond met the same assumptions (Figure 7, Appendix Table E2). Specifically, we found that estimates of cranial height and head depth were greater than expected in Crescent Pond along with estimates of orbit diameter for both F2 populations. Estimates of maxillary head protrusion were smaller than expected for Little Lake, and estimates of dentigerous arm width, dentigerous arm base, lower jaw length, palatine height, jaw closing in-lever, suspensorium length, nasal tissue protrusion and maxilla length were all smaller than expected in Crescent Pond (Figure 7).