One significant disadvantage of sexual reproduction is having to secure a mate. Having to find a mate means organisms would have to discover ways of attracting mates, which is very costly in terms of time and effort.
In many species, the male is the gender that has to do the attracting. Some engage in elaborate displays of plumage, others resort to sophisticated vocal calls and some must try to keep their harems of females by fending off their territories from encroaching males.
When a mate is found, the male generally has to prevent other males from getting to her. These defenses can range from scaring other males away from his territory to engaging in a duel to the death with competitors.