[math-fun] cicada periods
From Nature Magazine, 20 May 2004, "Big Buzz as cicadas arrive after 17-year gap"
Researchers say that in some places there will be more than 370 noisy, colorful insects per square meter. The scene will be "like a science fiction movie," enthuses May Berenbaum, who is an entomologist at the University of Illinois at Urbana-Champagne... [...] ...But perhaps the most interesting question about cicadas is why they spend 17 years underground, a cycle that has been recorded since the mid-nineteenth century. Biologists think it is no coincidence that cicadas have evolved to reappear with periods that are large prime numbers. If the life cycle of a breed were 12 years, they speculate, it would interbreed frequently with others that had life cycles of 2,3,4, or 6 years. "The prime number prevents mating between two broods and hybridization,'' says Christine Simon, an evolutionary biologist at the university of Connecticut. There are 13- and 17- year broods, and these can only meet up every 221 years, giving them ample time to forge their unmistakable identities * * * * "So many cicadas, so few recipes" (I read that somewhere else, forgot where) Thane Plambeck 650 321 4884 office 650 323 4928 fax http://www.plambeck.org
Isn't interbreeding a survival strategy? Scott Thane Plambeck wrote:
From Nature Magazine, 20 May 2004, "Big Buzz as cicadas arrive after 17-year gap"
Researchers say that in some places there will be more than 370 noisy, colorful insects per square meter. The scene will be "like a science fiction movie," enthuses May Berenbaum, who is an entomologist at the University of Illinois at Urbana-Champagne...
[...]
...But perhaps the most interesting question about cicadas is why they spend 17 years underground, a cycle that has been recorded since the mid-nineteenth century.
Biologists think it is no coincidence that cicadas have evolved to reappear with periods that are large prime numbers. If the life cycle of a breed were 12 years, they speculate, it would interbreed frequently with others that had life cycles of 2,3,4, or 6 years. "The prime number prevents mating between two broods and hybridization,'' says Christine Simon, an evolutionary biologist at the university of Connecticut. There are 13- and 17- year broods, and these can only meet up every 221 years, giving them ample time to forge their unmistakable identities * * * * "So many cicadas, so few recipes" (I read that somewhere else, forgot where)
Thane Plambeck 650 321 4884 office 650 323 4928 fax http://www.plambeck.org
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I remember reading an article (sorry don't remember where, but it might have been Scientific American), that asserted that the cycle periods of various Cicadas being prime (I guess that there are 7 and 11 year varieties), could be explained by trying to outlive predators -- the idea being to maximize the LCM of the predators lifespan with the Cicadas, so that there would be a large number of generations of predators between successive cicada generations, and there would be much less selective pressure for predators to specialize in cicadas (there wouldn't be much of a payoff). For a humorous look at cicadas (in Princeton we seem to have a local hot spot) see http://www.cicadaville.com/ -- Victor S. Miller | " ... Meanwhile, those of us who can compute can hardly victor@idaccr.org | be expected to keep writing papers saying 'I can do the CCR, Princeton, NJ | following useless calculation in 2 seconds', and indeed 08540 USA | what editor would publish them?" -- Oliver Atkin
On 26 May 2004 at 16:31, Victor S. Miller wrote:
I remember reading an article (sorry don't remember where, but it might have been Scientific American), that asserted that the cycle periods of various Cicadas being prime (I guess that there are 7 and 11 year varieties), could be explained ...
I recall that article, too --- could it have been in the Mathematical Intelligencer? /bernie\ -- Bernie Cosell Fantasy Farm Fibers mailto:bernie@fantasyfarm.com Pearisburg, VA --> Too many people, too few sheep <--
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