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Author Topic:   17-year locusts and evolution
Mespo
Member (Idle past 2884 days)
Posts: 158
From: Mesopotamia, Ohio, USA
Joined: 09-19-2002


Message 16 of 27 (108813)
05-17-2004 1:58 PM


Re: Signal
Why a signal, Redwolf? How about just an evolutionary niche that works.
*****************************
"Hey Crow. Here comes another locust variety. It's model 17."
"Cryin' out loud Blue Jay. Our nest is already crammmed with model 2, 6, and 13. The kids are pukin' their gizzards out. What are we supposed to do with 'em?"
"Well we can perch on the wires and watch cars slip and slide on their bodies and slam into telephone poles. Bring along a beetle sandwich. This should be fun."
(:raig

  
DBlevins
Member (Idle past 3775 days)
Posts: 652
From: Puyallup, WA.
Joined: 02-04-2003


Message 17 of 27 (108831)
05-17-2004 3:03 PM
Reply to: Message 1 by redwolf
05-16-2004 9:59 PM


Circadian Rythms
I may be mistaken and I went looking for where I might have read about it in my library but I believe Gould had a theory that the 17 yr. locust rythms has to do with the lifespan of the locust predators. That they evolved to take advantage of the shorter lifespan of the predators. Something like say some predator has a 15 year lifespan, and during this lifespan the locusts appear once, or possibly not at all. It may be a good food source but if it only appears once in the predators lifespan, there are better and more available foods out there.
I am sure that is quite a bit more complicated than that and I am probably missing some important points. I will keep looking to see if I can find more information.

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Mespo
Member (Idle past 2884 days)
Posts: 158
From: Mesopotamia, Ohio, USA
Joined: 09-19-2002


Message 18 of 27 (108843)
05-17-2004 3:36 PM


Insectivore in the 15 year life span category?
Hi DBlevins.
So, we're looking for an insectivore with a lifespan under 17 years? A bird, reptile or small mammal? And does anyone know just how far back in history the 17-year locust goes?
(:raig

  
redwolf
Member (Idle past 5791 days)
Posts: 185
From: alexandria va usa
Joined: 04-13-2004


Message 19 of 27 (108889)
05-17-2004 7:06 PM
Reply to: Message 17 by DBlevins
05-17-2004 3:03 PM


Re: Circadian Rythms

I may be mistaken and I went looking for where I might have read about it in my library but I believe Gould had a theory that the 17 yr. locust rythms has to do with the lifespan of the locust predators. That they evolved to take advantage of the shorter lifespan of the predators. Something like say some predator has a 15 year lifespan, and during this lifespan the locusts appear once, or possibly not at all. It may be a good food source but if it only appears once in the predators lifespan, there are better and more available foods out there.
That's an interesting idea but predators of an insect like the locust would mainly be birds with lifespans well under 17 years and, since the things seem to spend a lot of time at low levels, also dogs, cats, and anything else which eats insects and there'd be various lifespans in that mix.

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zephyr
Member (Idle past 4550 days)
Posts: 821
From: FOB Taji, Iraq
Joined: 04-22-2003


Message 20 of 27 (108905)
05-17-2004 8:14 PM
Reply to: Message 17 by DBlevins
05-17-2004 3:03 PM


Re: Circadian Rythms
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

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RAZD
Member (Idle past 1405 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 21 of 27 (108935)
05-17-2004 11:22 PM
Reply to: Message 20 by zephyr
05-17-2004 8:14 PM


but too many predators
The idea of predation driven must take into account the numbers of cicada predators, which are just too numerous for one to make a difference.
Consider, however, that all life cycles have some ups and downs, cyclic rhythms in populations. Thus any life cycle that matches those cycles is at hazard, while one that misses every now and then and has a boom year gets ahead. Prime numbers would do that in a general pattern system.

we are limited in our ability to understand
by our ability to understand
RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

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DC85
Member (Idle past 379 days)
Posts: 876
From: Richmond, Virginia USA
Joined: 05-06-2003


Message 22 of 27 (108942)
05-17-2004 11:47 PM
Reply to: Message 1 by redwolf
05-16-2004 9:59 PM


what exactly is your point?
the galapagos tortoise can live 150-200 ... and other tortoise speices don't even come close... so what?

My site The Atheist Bible
My New Debate Fourms!

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KCdgw
Inactive Member


Message 23 of 27 (109013)
05-18-2004 10:40 AM


Competition, not predation
I think the predator angle is less convincing than the ecological angle: 17 year locusts don't have to compete for resources with 13 year locusts. Selection will favor staggered emergent years.
KC

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Unseul
Inactive Member


Message 24 of 27 (109049)
05-18-2004 2:31 PM
Reply to: Message 23 by KCdgw
05-18-2004 10:40 AM


Re: Competition, not predation
Wonder if we're gonna get a super mega flood anytime in our lifetime, when the two species do coincide. Once every 221 years by my reckoning. That could be impressive.
Unseul

Give a man a fire and he's warm for a day. Set a man on fire and he's warm for the rest of his life....

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zephyr
Member (Idle past 4550 days)
Posts: 821
From: FOB Taji, Iraq
Joined: 04-22-2003


Message 25 of 27 (109054)
05-18-2004 3:06 PM
Reply to: Message 24 by Unseul
05-18-2004 2:31 PM


Re: Competition, not predation
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?

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KCdgw
Inactive Member


Message 26 of 27 (109061)
05-18-2004 3:30 PM
Reply to: Message 25 by zephyr
05-18-2004 3:06 PM


Re: Competition, not predation
I'm not that well-informed about cicadas particularly. I just think the attention to the predation issue may eclipse what may ultimately be behind the staggered emergence cycles.
KC
This message has been edited by KCdgw, 05-18-2004 02:30 PM

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 27 of 27 (109089)
05-18-2004 4:59 PM
Reply to: Message 25 by zephyr
05-18-2004 3:06 PM


Re: Competition, not predation
Actually, yes they are syncronized, and that is the wonder of it.

Aslan is not a Tame Lion

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