Study of sperm variation in two species of frogs, Pelophylax redibundus and Ranamacrocnemis from north of Iran

Recent studies showed that variation in sperm morphology within species is influenced by sperm competition. The evolutionary models predict an increase in variation in sperm size or number when sperm competition is relaxed. Thus species with more sperm competition show less variation in sperm length. For experiment of this model, we studied the sperm length of 5 male individuals of marsh frog (Pelophylax redibundus), a species in which males encounter no sperm competition, and 2 males of wood frog (Rana macrocnemis), a species with no information of sperm competition during the breeding season in north of Iran. Their testes were carefully crushed in petri dishes in about 3 ml of water. The sperm length was measured to the nearest 0.1 μm on each sperm. As expected, sperm size in marsh frog was highly variable, largely due to variation in flagellum length within and among individual males. Also we observed high sperm variation in wood frog. This study demonstrates that, within marsh frogs there are marked interspecific differences in sperm morphology as a reflection to lake of sperm competition in this species. As well as we predict that there is little or no sperm competition in wood frog.

کلیدواژه ها:

Sperm competition ، Marsh frog ، Wood frog