RESULTS
All fluid viscosity measures collected from the female reproductive tracts of each focal Peromyscus species are reported in Table 1. We found that the viscosity of fluids in both the uterus and the oviduct significantly differed based on mating system in Peromyscus mice. More specifically, polyandrous species have significantly more viscous fluid in the uterus (LM: F1,1255 = 27.09, p < 0.001) but significantly less viscous fluid in the oviduct (LM: F1,1755 = 24.7, p < 0.001) than monogamous species (Figure 1). Within-species analyses revealed that fluids were significantly more viscous when collected from the uterus compared to the oviduct in P. maniculatus , P. leucopus , and P. californicus , but the opposite was true in P. eremicus andP. polionotus ; no difference was observed in the viscosity of uterine fluid or oviductal fluid in P. gossypinus , however (Table 1).
We found that the reproductive fluid pH of the focal polyandrous species, P. maniculatus , was significantly higher within the uterus (LM: F1,18 = 17.05 p < 0.001) and oviduct (LM: F1,18 = 14.39, p < 0.01) compared to its monogamous congener, P. polionotus (Table 2, Figure 2). However, we found no differences in calcium concentrations between these species in either the fluids collected from the uterus (LM: F1,18 = 2.005, p = 0.174) or from the oviduct (LM: F1,18 = 0.3423, p = 0.566; Table 2, Figure 3). Within both species, the fluid collected from the uterus had a significantly higher pH than the oviduct (paired t-test: P. maniculatus t = 21, df = 9, p < 0.001; P. polionotus t = 6.986, df = 9, p < 0.001; Figure 2). In P. maniculatus , the fluid collected from the uterus was significantly more calcemic (paired t-test: t = 3.95, df = 9,p < 0.01), a pattern that was not observed in P. polionotus (paired t-test: t = 1.98, df = 9, p = 0.079).