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<H2><FONT size=3>American Journal of Botany 2007;94:2059-2062</FONT></H2>
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<H2>Phylogenetic evidence for a flower size and number trade-off<A name=RFN1></A><SUP>1</SUP></H2><STRONG></NOBR><NOBR>Risa D. Sargent<A name=RFN6></A><SUP>6</SUP></NOBR>, <NOBR>Carol Goodwillie<A name=RFN7></A><SUP>7</SUP></NOBR>, <NOBR>Susan Kalisz<A name=RFN8></A><SUP>8</SUP></NOBR> and <NOBR>Richard H. Ree<A name=RFN9></A><SUP>9</SUP></NOBR> </STRONG>
<P><FONT size=-1>Department of Integrative Biology, University of California, Berkeley, California 94720-3140 USA; Department of Biology, East Carolina University, Greenville, North Carolina 27858-4353 USA; Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 USA; Field Museum of Natural History, Botany Department, 1400 S. Lake Shore Drive, Chicago, Illinois 60605 USA </FONT>
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<P><FONT size=+1><STRONG>ABSTRACT</STRONG></FONT>
<P>The size and number of flowers displayed together on an inflorescence<SUP> </SUP>(floral display) influences pollinator attraction and pollen<SUP> </SUP>transfer and receipt, and is integral to plant reproductive<SUP> </SUP>success and fitness. Life history theory predicts that the evolution<SUP> </SUP>of floral display is constrained by trade-offs between the size<SUP> </SUP>and number of flowers and inflorescences. Indeed, a trade-off<SUP> </SUP>between flower size and flower number is a key assumption of<SUP> </SUP>models of inflorescence architecture and the evolution of floral<SUP> </SUP>display. Surprisingly, however, empirical evidence for the trade-off<SUP> </SUP>is limited. In particular, there is a lack of phylogenetic evidence<SUP> </SUP>for a trade-off between flower size and number. Analyses of<SUP> </SUP>phylogenetic independent contrasts (PICs) of 251 angiosperm<SUP> </SUP>species spanning 63 families yielded a significant negative<SUP> </SUP>correlation between flower size and flower number. At smaller<SUP> </SUP>phylogenetic scales, analyses of individual genera did not always<SUP> </SUP>find evidence of a trade-off, a result consistent with previous<SUP> </SUP>studies that have examined the trade-off for a single species<SUP> </SUP>or genus. Ours is the first study to support an angiosperm-wide<SUP> </SUP>trade-off between flower size and number and supports the theory<SUP> </SUP>that life history constraints have influenced the evolution<SUP> </SUP>of floral display.<SUP> </SUP>
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<P><STRONG>Key Words:</STRONG> floral display • flower number • flower size • inflorescence size • life history trade-offs • phylogenetic independent contrasts
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<DIV><FONT lang=0 face=Arial color=#004000 size=3 FAMILY="SANSSERIF" PTSIZE="12">Laurie Davies Adams<BR>Executive Director<BR>Coevolution Institute<BR>423 Washington St. 5th<BR>San Francisco, CA 94111<BR>415 362 1137<BR>LDA@coevolution.org<BR><A title=http://www.coevolution.org/ href="http://www.coevolution.org/">http://www.coevolution.org/</A></FONT><FONT lang=0 face=Arial color=#004000 size=3 FAMILY="SANSSERIF" PTSIZE="12"><BR><A title=http://www.pollinator.org/ href="http://www.pollinator.org/">http://www.pollinator.org/</A></FONT><FONT lang=0 face=Arial color=#004000 size=3 FAMILY="SANSSERIF" PTSIZE="12"><BR><A title=http://www.nappc.org/ href="http://www.nappc.org/">http://www.nappc.org/</A></FONT><FONT lang=0 face=Arial color=#004000 size=3 FAMILY="SANSSERIF" PTSIZE="12"><BR><BR>Join the Pollinator Partnership to save the bees, bats, butterflies and more! See <A title=http://www.pollinator.org/ href="http://www.pollinator.org/">http://www.pollinator.org/</A></FONT><FONT lang=0 face=Arial color=#004000 size=3 FAMILY="SANSSERIF" PTSIZE="12"> for more information.<BR><BR><B><I>Our future flies on the wings of pollinators.<BR><BR></FONT><FONT lang=0 face=Arial color=#000000 size=2 FAMILY="SANSSERIF" PTSIZE="10"></I>Please consider the environment before printing this email.</B></FONT></DIV><BR><BR><BR><DIV><FONT style="color: black; font: normal 10pt ARIAL, SAN-SERIF;"><HR style="MARGIN-TOP: 10px">See AOL's <A title="http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004" href="http://food.aol.com/top-rated-recipes?NCID=aoltop00030000000004" target="_blank">top rated recipes</A> and <A title="http://body.aol.com/fitness/winter-exercise?NCID=aoltop00030000000003" href="http://body.aol.com/fitness/winter-exercise?NCID=aoltop00030000000003" target="_blank">easy ways to stay in shape</A> for winter.</FONT></DIV></BODY></HTML>