Why does maladaptive behavior persist in moths?

[mellowmorgan]

For billions of years, the only bright objects in the night sky were stars or the moon. Night-flying moths used to navigate in a straight
line. Today, the instinct to fly toward bright objects causes moths to exhaust themselves fluttering around streetlights and banging against brightly lit windowpanes. This behavior is not adaptive, so why does it persist?

[Moontanman]

I would suggest that either street lights haven't been around long enough to have a large effect or the behavior is still doing it's job and not enough moths are affected by it to matter or it's not as big a maladaptation as it looks...

[mellowmorgan]

I would suggest that either street lights haven't been around long enough to have a large effect or the behavior is still doing it's job and not enough moths are affected by it to matter or it's not as big a maladaptation as it looks...

It seems rather self-destructive, if you ask me, considering that before electricity we used lamp and candlelight, and before that, fire for the majority of our existence. But my guess would've been that distinguishing between lights that are harmful would've required a larger brain, not a single trait like colour or pattern achieved through natural selection, but I'm not so knowledgeable on this topic...

[StringJunky]

Maybe it is reproductively beneficial behaviour because it increases the likelihood of moths chancing upon each other by concentrating them in imore discrete zones

[Ringer]

Like StringJunky said, behavior doesn't have to be pleasant to be adaptive. If banging your head into a wall repeatedly allowed you access to more mates that trait of banging your head would probably persist as long as you had time to reproduce. If all moths are attracted to light staying near a light source will increase the probability of finding a mate. Those that do not stay near a light source and will not mate, so the trait of avoiding light sources will not be passed on.

[John Cuthber]

In the cases where it's maladaptive the moth flies into the flame and the trait does not persist.

In the cases where the trait is beneficial the moth survives and has children and so the trait persists.

We don't see the dead moths' children (because they don't exist) so we don't see the population that arose from situations where the trait was maladaptive.

[overtone]

Whatever the trait is that streetlights screw up, it may not be persisting: moths (at least the bigger ones that I can identify visually in passing) are quite a bit less common around lights than they used to be, in every location I can compare.

 

It's possible that these moths I rcognize are much reduced in population in my areas of observation. It's also possible that a large and increasing fraction of the population no longer gets trapped by lights as easily or as often, for whatever reason, and so I don't see them.