3.4 Path analyses
We conducted a rigorous pathway analysis to explore how ornament traits and morphometric traits influenced female and male incubation parental care investment under different temperature regimes (above or below the mean temperature). We evaluated a large set of 85 candidate models (see supplementary material for details, Table S5-S8) and identified the best-supported models for temperatures above and below the mean (Figure 3) based on the lowest AICc values that passed the Fisher’s C test (Table S5, S7).
Below the mean temperature, we found that females spent less time incubating than males (t test: t = -13.492, p < 0.001, Figure 3a), and the incubation investment of both males and females was primarily influenced by ambient temperature rather than male or female ornament color and body size (Figure 3a, Table S5, S6). In contrast, above the mean temperature, females spent more time incubating than males (t test: t = 6.163, p < 0.001, Figure 3b). Interestingly, we observed that male ornament color was positively correlated with female incubation investment and negatively correlated with male incubation investment (Figure 3b, Table S7, S8), while neither female body size nor male body mass had a significant effect on parental incubation investment.