There are plenty of places where the cicadas do not have these long periodicities. Jm From: IN%"math-fun@mailman.xmission.com" "math-fun" 26-MAY-2004 11:14:30.34 To: IN%"math-fun@mailman.xmission.com" "math-fun" CC: Subj: RE: [math-fun] cicada periods Return-path: <math-fun-bounces+mckay=vax2.concordia.ca@mailman.xmission.com> Received: from bonnie.concordia.ca (bonnie.Concordia.CA [132.205.7.81]) by vax2.concordia.ca (PMDF V6.2 #30759) with ESMTP id <01LAJQRBP2IO0089BI@vax2.concordia.ca> for mckay@vax2.concordia.ca (ORCPT mckay@vax2.concordia.ca); Wed, 26 May 2004 11:14:29 -0400 (EDT) Received: from mailman.xmission.com (mailman.xmission.com [198.60.22.29]) by bonnie.concordia.ca (8.12.10/8.12.10) with ESMTP id i4QFERA0023845 for <mckay@vax2.concordia.ca>; Wed, 26 May 2004 11:14:28 -0400 Received: from localhost ([127.0.0.1] helo=mailman.xmission.com) by mailman.xmission.com with esmtp (Exim 3.36 #1 (Debian)) id 1BT06t-0005gi-03 for <mckay@vax2.concordia.ca>; Wed, 26 May 2004 09:14:27 -0600 Received: from mgr8.xmission.com ([198.60.22.208] ident=mail) by mailman.xmission.com with esmtp (Exim 3.36 #1 (Debian)) id 1BT06m-0005gb-00 for <math-fun@mailman.xmission.com>; Wed, 26 May 2004 09:14:20 -0600 Received: from [24.75.96.125] (helo=smtp.firstva.com) by mgr8.xmission.com with esmtp (Exim 4.31) id 1BT06j-0004XQ-T0 for math-fun@mailman.xmission.com; Wed, 26 May 2004 09:14:20 -0600 Received: from [4.240.87.156] (helo=nexet.net) by smtp.firstva.com with asmtp (Exim 4.24) id 1BSzuI-0005kO-4o for math-fun@mailman.xmission.com; Wed, 26 May 2004 11:01:26 -0400 Date: Wed, 26 May 2004 09:13:28 -0500 From: scott beaver <sbeaver@nexet.net> Subject: Re: [math-fun] cicada periods In-reply-to: <005001c442e5$7dc84f40$a52efea9@TASSO> Sender: math-fun-bounces+mckay=vax2.concordia.ca@mailman.xmission.com To: math-fun <math-fun@mailman.xmission.com> Errors-to: math-fun-bounces+mckay=vax2.concordia.ca@mailman.xmission.com Reply-to: math-fun <math-fun@mailman.xmission.com> Message-id: <40B4A608.8080400@nexet.net> MIME-version: 1.0 Content-type: text/plain; format=flowed; charset=us-ascii Content-transfer-encoding: 7bit X-Accept-Language: en-us, en Precedence: list User-Agent: Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.5) Gecko/20031007 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on mgr8.xmission.com X-Spam-Level: X-Spam-Status: No, hits=-0.9 required=8.0 tests=BAYES_30 autolearn=no version=2.63 X-SA-Exim-Connect-IP: 24.75.96.125 X-SA-Exim-Mail-From: sbeaver@nexet.net X-SA-Exim-Version: 4.0 (built Sat, 24 Apr 2004 12:31:30 +0200) X-SA-Exim-Scanned: Yes (on mgr8.xmission.com) X-BeenThere: math-fun@mailman.xmission.com X-Mailman-Version: 2.1.4 X-Scanned-By: MIMEDefang 2.35 References: <005001c442e5$7dc84f40$a52efea9@TASSO> List-Post: <mailto:math-fun@mailman.xmission.com> List-Subscribe: <http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun>, <mailto:math-fun-request@mailman.xmission.com?subject=subscribe> List-Unsubscribe: <http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun>, <mailto:math-fun-request@mailman.xmission.com?subject=unsubscribe> List-Archive: <http://mailman.xmission.com/cgi-bin/mailman/private/math-fun> List-Help: <mailto:math-fun-request@mailman.xmission.com?subject=help> List-Id: math-fun <math-fun.mailman.xmission.com> Original-recipient: rfc822;mckay@vax2.concordia.ca 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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