Studies of biparental mammals demonstrate that males may undergo systematic changes in body mass as a consequence of changes in reproductive status; however, these studies typically have not teased apart effects of specific social and reproductive factors, such as cohabitation with a female per se, cohabitation with a breeding female specifically, and engagement in paternal care. We aimed to determine whether California mouse (Peromyscus californicus) fathers undergo systematic changes in body mass and if so, which specific social/reproductive factor(s) might contribute to these changes. We compared mean weekly body masses over a 5-week period in 1) males housed with another male vs. males housed with a non-reproductive (tubally ligated) female; 2) males housed with a tubally ligated female vs. males housed with a female that was undergoing her first pregnancy; and 3) experienced fathers housed with vs. without pups during their mate's subsequent pregnancy. Body mass did not differ between males housed with another male and those housed with a non-reproductive female; however, males housed with a non-reproductive female were significantly heavier than those housed with a primiparous female. Among experienced fathers, those housed with pups from their previous litter underwent significant increases in body mass across their mates' pregnancy, whereas fathers housed without pups did not. These results suggest that male body mass is reduced by cohabitation with a breeding (pregnant) female, but not by cohabitation with a non-reproductive female, and that increases in body mass across the mate's pregnancy are associated with concurrent care of offspring rather than cohabitation with a pregnant female. Additional work is needed to determine the mechanisms and functional significance, if any, of these changes in male body mass with reproductive condition.

中文翻译：

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父母身份对一夫一妻制双亲加利福尼亚小鼠雄性体重的影响

对双亲哺乳动物的研究表明，由于生殖状态的变化，雄性的体重可能会发生系统性变化；然而，这些研究通常没有区分特定社会和生殖因素的影响，例如与女性本身的同居、与生育女性的同居以及参与父亲的照顾。我们的目的是确定加利福尼亚小鼠 (Peromyscus californicus) 的父亲是否经历了体重的系统性变化，如果是，哪些特定的社会/生殖因素可能导致这些变化。我们比较了 5 周内的平均每周体重 1) 与另一只雄性同住的雄性与与非生殖性（输卵管结扎）雌性同住的雄性；2) 男性与输卵管结扎女性 vs 女性。与第一次怀孕的女性同住的男性；和 3) 有经验的父亲在其配偶随后的怀孕期间饲养与不饲养幼崽。与另一只雄性同住的雄性和与非生殖性雌性同住的雄性之间的体重没有差异；然而，与没有生育能力的雌性同住的雄性比与初产雌性同住的雄性重得多。在有经验的父亲中，饲养前窝幼崽的父亲在配偶怀孕期间体重显着增加，而没有幼崽的父亲则没有。这些结果表明，与繁殖（怀孕）雌性同居会减少雄性体重，但与非生殖性雌性同居不会减少雄性体重，而且整个配偶的体重都会增加。s 怀孕与同时照顾后代有关，而不是与怀孕的女性同居​​。需要额外的工作来确定这些男性体重与生殖条件变化的机制和功能意义（如果有的话）。