Female mice housed with castrated males have higher stress levels, & actively avoid such housing partners when provided with a refuge; seem to actively avoid males with low levels of testosterone

Female mice seek refuge from castrated males, but not intact or vasectomized males, mitigating a socially-induced glucocorticoid response. Teagan J. Gale, Michael G. Garratt, Robert C. Brooks. Physiology & Behavior, September 7 2019, 112678. https://doi.org/10.1016/j.physbeh.2019.112678

Highlights
•  Female mice housed with castrated males have higher stress levels.
•  Female mice housed with castrated males actively avoid their housing partner when provided with a refuge.
•  We suggest that females actively avoid males with low levels of testosterone, and that their surrounding social partners can affect their physiology.

Abstract: Sexual conflict may be manifested during social interactions, shaping the costs of reproduction in sexually reproducing species. This conflict, and the physical necessity of intromission, can intensify the already costly nature of reproduction for female mammals. To identify and partition the costs that males inflict on females during mating and reproduction, we paired female mice with either other females or castrated, vasectomised, or intact (sham-vasectomised) males, thus manipulating exposure to social mating behavior and costs arising from fertilization. We also provided females with refuges where males could not enter, to test whether females show avoidance or attraction to males of different gonadal status expected to exhibit different levels of social behavior. We found that females paired with vasectomised and castrated males spent the most time in their refuge. Females housed with castrated males also had increased glucocorticoid levels, an effect that was mitigated when females could retreat from these males to a refuge. This suggests that females actively refuge from castrated males, and that housing with such males is sufficient to generate an increased glucocorticoid response. Our results show that females choose to refuge from males depending on the partner’s gonadal status, choices that are linked to social induced stress responses but not exposure to male mating behaviour.

Keywords: RefugeStressCosts of reproductionCastration