17-year locusts and evolution

quote:

---

Another theory the article mentions is that it could be to prevent interbreeding between the species, reducing the chance of a hybrid occuring, and if it does occur using such large prime numbers reduces the chance of the hybrid breeding again. But im not sure how selection would work on this either.

---

It sounds like they've got the cart before the horse on that one. Species don't evolve new traits for the purpose of creating/maintaining reproductive isolation; rather, isolation allows the accumulation of traits that produce separate species. Unless you think evolution is guided at every step, it doesn't hold water.
I always found the predator idea very intriguing, but I don't know enough cicada specifics to really judge its merits.

quote:

---

It's really hard to picture something like that evolving.

---

I always to my best to recognize when I'm mistaking my own lack of imagination for a real-life impossibility. Try it!

quote:

---

My own GUESS would be that the 17 year locust was originally designed as a signal of some sort, i.e. as a sign for some recurring event or celebration at 17-year intervals.

---

Why is that... because ancient people couldn't count that high?

quote:

---

I mean, if some biting fly or mosquito came out every 17 years you might figure it to be a microevolutionary adaptation but the locust is decorative like butterflies.

---

Decorative? Some people hate them. They scared the crap out of me as a kid. I love 'em now, especially deep-fried with ketchup Regardless, the sensory response of a common species of primates to a particular insect is an incredibly poor basis for speculation as to the insect's origins.

I believe it was Dawkins who speculated that the prime number was the result of an evolutionary arms race (a term he likes to use and, I believe, he coined) with a predator having a similar (but shorter) life cycle. Thus, if they were at 16 years, the odd generations of an 8-year predator would still profit from cicada-hunting, but the change to 17 would skew the cycle and result in nearly no cicada catch by the same predator.Interesting speculation, as I see it. Would be even more interesting if a likely suspect could be pointed out....This message has been edited by zephyr, 05-17-2004 07:15 PM

Since a few of us seem to be well-informed about cicadas, I'm just curious... with the 17-year species, how much do the numbers vary from year to year? They're not all synchronized, are they?