#negative or dubiously helpful traits can get selected for if they help you mate

[aplpaca]

fun fact that bc of one of their claws being Obnoxiously Fucking Huge, male fiddler crabs literally can't eat with it. Which means they spend like twice as much time eating as females, since females can shovel food into their mouth with both claws but males can only do it with one

This relates to the concept of "honest/costly signaling" in ecology, which contains the idea that traits that attract mates can be an accurate display of an individual's fitness/capability due to said trait actually having disadvantages (ex. long attractive tails in some birds making moving more difficult, large claws making it harder to eat, being brightly colored making you more visible to predators, etc). The idea being that if certain attractive traits are actually disadvantageous, then an organism thriving and being overall healthy despite said traits is evidence that said organism is Good At Surviving, and therefore a good potential mate.

So while bigger claws do have the benefit of giving a male fiddler crab an edge in fights with other males, which play a big role in female mate choice, a male being healthy while having his bigass claw in the first place also serves as indirect proof that he's good at successfully obtaining enough food to survive

but like. look at this dude. he can't eat with that thing. he's got one functional food shovel bc the women think him having a one-purpose bigass muscle arm is Good Baby Material. and they're not even technically wrong