The mythical Eurasian magnetic pinching beetle is able to produce and detect subtle variations in local magnetic fields. Male magnetic pinching beetles provide extensive parental care; they stick eggs to their backs using biomagnetic fields and once the space on their back is occupied, they cannot accept more eggs. Once the eggs hatch, males locate and process ferrous-rich food for the young. Female magnetic pinching beetles, on the other hand, provide no parental care. Instead, she simply leaves her tiny eggs with each of the several males with which she mates. Females attract males by producing a long-range magnetic pulse, which also serves as an honest index of female genetic quality and health because it is energetically costly to sustain and impossible to fake. They broadcast this mating call from large metal objects that amplify the signal. Males select females mates based on several factors, including the sheen of her metallic shell and the iron content of a small pebble she provides before laying eggs on the male’s back. All this mate choice and reproduction happens quickly; when the rainy season comes, adults get rusty and, no longer able to move, die. Given this description and what you know about mating system evolution, which of the following appear to be reasonable, fitness-enhancing strategies?
Instead of spending time finding her own iron-rich pebble, females might enhance their fitness by stealing pebbles from other females.
Low-quality females could enhance their fitness by sitting within the long-range magnetic signal of a high quality female and attempting to intercept males as they come in to mate.
When a female finds a male, she could enhance her fitness by depolarizing him, causing him to shed the eggs other females have attached to his back and thereby making more space for her own eggs.
A female could defend prime-broadcasting locations from other females, giving her exclusive access to the males attracted to the signal she broadcasts from her high-quality spot.
Females could stick themselves magnetically to a male, thereby preventing him from mating with other females.
Females could reverse the polarity of the magnetic sensing organ in a male after mating with him, thereby making him unable to find other females.
All of the above are sound fitness-enhancing strategies.
None of the above are sound fitness-enhancing strategies.