Hormones orchestrated pre- and post-copulatory sexual traits in male Mongolian gerbils.
Parker's sperm competition model predicts a negative relationship between pre-copulatory (social status) and post-copulatory (sperm quality and quantity) sexually selected traits, however, empirical studies have revealed considerable inconsistency in this relationship. We hypothesized that there was a trade-off between pre- and post-copulatory sexually selected traits, and hormones (corticosterone, CORT; testosterone, T) orchestrate this relationship. In this study, we measured energetic parameters in the dominant-subordinate Mongolian gerbils (Meriones unguiculatus), whose relationship was established under chronic social encounters in a neutral arena, and then tested the relationship between their social status and sperm quality and quantity. Our results showed that dominant males initiated attack sooner and displayed more aggression, self-grooming and locomotion behaviors in daily social encounters across seven consecutive days. Dominant gerbils also had more and better quality of sperm than that of subordinate males, yet showed no significant differences in energy intake and RMR in comparison with subordinate individuals. In addition, dominant males had higher concentrations of serum T than subordinate males, whereas the concentrations of CORT showed a reverse pattern. The frequency and duration of aggression (indicative of social status) increased with elevated T concentrations. Sperm quality in terms of number and activity were associated with higher concentrations of serum T in dominant gerbils, whereas small sperm counts and poor-quality sperm were associated with relatively higher concentrations of serum CORT in subordinate gerbils. Together, our data indicated that there was no trade-off between pre- and post-copulatory sexually selected traits but hormones orchestrated the relationship between these traits in male Mongolian gerbils.
Ministry of Education, Key Laboratory of Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, China; State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
Wei
W
Shen
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: zhangxy@ioz.ac.cn.
Xue-Ying
XY
Zhang
Ministry of Education, Key Laboratory of Biodiversity Science and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
Ding-Zhen
DZ
Liu
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
De-Hua
DH
Wang
D000374:Aggression; D000818:Animals; D015992:Body Mass Index; D003345:Corticosterone / Q000097:blood*; D004291:Dominance-Subordination; D002149:Energy Intake / Q000502:physiology; D005849:Gerbillinae; D008297:Male; D012119:Respiration; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology; D018709:Statistics, Nonparametric; D013739:Testosterone / Q000097:blood*; D013997:Time Factors
D013739:Testosterone; D003345:Corticosterone
Corticosterone (CORT); Energy intake; Mongolian gerbil; Social status; Sperm quality; Testosterone (T)