SSI generalist-only populations exhibit unique P matrix properties that are not observed in Caribbean or SSI radiating populations.
The visualization of the PCA suggests that the P matrix of SSI generalist-only populations is distinct from both the Caribbean and SSI radiating groups (Figure 4). In direct comparisons, we found that the SSI radiating, and Caribbean groups had the highest level of PCA similarity indicating that the P matrices of these two populations are extremely similar (Figure 5; Appendix Table C1). Direct comparisons of each of these groups with SSI generalist-only populations also indicates that their P matrices are significantly different. Specifically, the P matrix of the SSI generalist-only group has significantly higher levels of integration, constraints and mean squared correlation between traits, with simultaneously lower estimates of flexibility than the P matrices of SSI radiating and Caribbean populations (Figure 6; Appendix Table C2). In fact, there are only two P matrix features for which the SSI generalist-only group is similar to other pupfish populations: respondability and autonomy. For respondability, both SSI radiating and SSI generalist-only populations exhibited similar values (respondability= ~0.09), while the Caribbean population value was approximately half of this estimate (respondability= 0.048). On the other hand, autonomy estimates for the Caribbean and SSI generalist-only group were extremely similar (autonomy=~0.07), while the P matrix of SSI radiating populations had significantly lower values (autonomy=0.034) (Figure 6; Appendix Table C2).