Sperm strategies in rodents

Rodents exhibit diverse biology, mating systems and diverse sperm morphology. Different levels of sperm competition have therefore been found in this group. Generally, it is accepted that sperm competition in animals causes the prolongation of sperm tails. However, what other sperm morphological adaptations in rodents are affected by sperm competition? Species-specific sexual selection likely optimizes sperm morphology. Sperm physiology, morphology and competition may be influenced, ultimately, by environmental factors. This Ph.D. thesis focuses on sperm competition in murine rodents. The thesis contains three research articles (including one as a submitted manuscript). In addition, another published article, partialy related to the topic of this thesis, is represented in the Appendix. The sperm morphology in rodents plays an important role in sperm competition. Longer tails and apical hooks are usually found in the species with relatively larger testes and with higher percentage of multiple paternity (i.e. rate of promiscuity), that is in species with the higher risk of sperm competition. The goal of the first study was to investigate the relationships between relative testis weight and sperm traits (apical hook and tail lengths and variance in this traits). The apical hook length was positively..