Final answer:
Male pipefish selecting females with fewer parasites is an example of intersexual selection, where one sex chooses mates based on certain traits that indicate health and potential for reproductive success.
Step-by-step explanation:
Male pipefish selecting less parasite-ridden females for mating is an example of intersexual selection.
In intersexual selection, individuals of one sex (typically females) select mates of the other sex based on certain desirable traits. This contrasts with intrasexual selection, where members of the same sex compete against each other for the opportunity to mate.
Intersexual selection leads to the evolution of traits that may not necessarily enhance survival but are attractive to the opposite sex, and it includes a variety of cues such as visual, aural, tactile, and chemical signals. In this case, male pipefish are preferring females that display signs of health through low parasite loads, thereby utilizing visual and possibly chemical cues to select a healthy mate, which may translate to higher reproductive success and healthier offspring.