Sperm ATP balance and swimming efficiency: the role of sperm competition in the evolution of sperm bioenergetics

TOURMENTE, MAXIMILIANO; VAREA SÁNCHEZ, MARÍA; ROLDAN, EDUARDO R. S.

Holderness

Conferencia; Gordon Research Conference: Fertilization & Activation of Development; 2015

Gordon Research Conferences

Selection by sperm competition has been proposed as an important evolutionary cause of diversity in sperm traits. In rodents, high sperm competition levels associate with the maintenance of faster sperm swimming velocities, which depend on the ability of sperm to sustain high concentrations of intracellular ATP over time. Since the amount of ATP available for sperm motility results from the balance between ATP production and ATP consumption rates, an increase in sperm velocity may be attained through variations in these two parameters. We examined the variability in sperm ATP production pathways and ATP consumption rates among a group of mouse species with different levels of sperm competition. We found that the sperm of species with higher sperm competition levels showed higher OXPHOS/glycolysis ratios and were able to produce increased amounts of ATP and achieve higher swimming velocities. With regards to sperm ATP expenditure, sperm of species that consumed ATP at a higher rate were able to swim at a faster velocity. Moreover, in addition to consuming more ATP per second, sperm of species with higher levels of sperm competition were capable of swimming longer distances per unit of ATP consumed. Thus, our findings suggest that sperm competition promotes an increase in sperm swimming velocity through (a) adaptations in sperm metabolism (i.e., ATP production and consumption rates), and (b) an increment in the energetic efficiency of sperm swimming.