Final answer:
Sexual selection could favor repeatability in male gill flaring duration if females prefer the trait as an indicator of male fitness, stamina, or genetic quality. Traits that translate into increased attractiveness to females can be selected for, even if they come at a survival cost to the male, as explained by the handicap principle and the good genes hypothesis.
Step-by-step explanation:
In the context of sexual selection, repeatability in male gill flaring duration could be selected for if females prefer males that exhibit a longer, consistent signaling duration. Female preference can drive sexual selection, leading to the exaggeration of certain traits in males.
For example, with the three-spined stickleback fish, the males develop a bright red belly and react strongly to certain stimuli during mating season, exhibiting a fixed action pattern. Similarly, if female fish are attracted to males who can maintain a longer gill flare, perhaps as an indicator of stamina or fitness, those males might have greater reproductive success.
The handicap principle could also apply, suggesting that only the fittest males can afford to perform longer gill flares without falling prey to predation. In addition, the good genes hypothesis proposes that these longer durations of gill flares may signal genetic superiority, providing healthier offspring, and thus, being favored by females during mate selection.