[R] Heatmap construction problems

[Struchtemeyer, Chris]

I am very new to R and don't have any computer program experience
whatsoever.  I am trying to generate a heatmap of the following data:

   
   
 Phylum,AI,AJT,BY,GA,Grt,Sm
 Acidobacteria,0.5,0.7,2.7,0.1,2.6,1.0
 Actinobacteria,33.7,65.1,9.7,2.0,3.9,2.1
 Bacteroidetes,9.7,5.6,0.7,13.2,41.1,21.6
 CCM11b,0.0,0.0,0.0,0.0,0.0,0.1
 Chlamydiae,0.1,0.1,0.0,0.0,1.0,0.2
 Chlorobi,0.0,0.0,0.0,0.0,0.7,1.0
 Chloroflexi,0.1,0.2,0.6,0.2,0.8,0.6
 Cyanobacteria,18.7,0.0,1.0,1.5,0.9,0.3
 Ellusimicrobiales,0.0,0.0,0.0,0.0,0.0,0.0
 Firmicutes,1.0,7.6,8.3,31.9,2.1,6.9
 Gemmatimonadetes,5.0,0.3,0.3,0.0,0.1,0.0
 GN02,0.0,0.0,0.0,0.0,0.0,0.5
 Nitrospirae,0.0,0.2,1.1,0.0,0.0,0.0
 NKB19,0.0,0.0,0.9,0.0,0.0,0.0
 OP8,0.0,0.1,0.0,0.0,0.0,0.0
 OP10,0.6,0.2,0.5,0.0,0.6,0.6
 Planctomycetes,0.9,0.5,6.5,2.2,2.0,2.3
 Alphaproteobacteria,7.8,10.7,21.8,12.2,5.3,26.8
 Betaproteobacteria,9.9,2.8,8.9,21.7,8.3,21.9
 Deltaproteobacteria,0.5,0.2,1.8,2.0,1.2,7.1
 Epsilonproteobacteria,0.0,0.0,0.0,0.1,0.0,0.2
 Gammaproteobacteria,4.0,2.5,8.0,9.4,24.7,5.4
 SC4,0.0,0.0,0.0,0.0,0.7,0.0
 SM2F11,0.0,0.0,0.0,0.0,0.2,0.0
 SPAM,0.0,0.1,0.0,0.0,0.1,0.1
 Synergistes,0.0,0.0,0.0,0.1,0.0,0.0
 Deinococcus-Thermus,0.0,0.0,0.0,0.0,0.0,0.0
 TM6,0.1,0.0,0.0,0.0,0.1,0.0
 TM7,0.0,0.1,0.4,0.0,0.4,0.1
 Verrucomicrobia,3.8,2.1,23.2,2.9,1.3,0.5
 WPS-2,0.0,0.0,0.1,0.0,0.0,0.0
 WS3,0.0,0.0,0.0,0.0,0.0,0.1
 Uncl Bacteria,3.7,1.2,3.7,0.4,1.9,0.8

I am a microbiologist.  What I want to do is construct a heatmap showing the
relative abundance of each phylum.  The far left column of my table contains
all of the phylum names I observed in a set of 6 water samples and each of
the columns to the right contains the relative abundance (%) of each phylum
in each water sample.  I have tried constructing a heatmap using the ggplot
guidelines listed at the following site:
http://learnr.wordpress.com/2010/01/26/ggplot2-quick-heatmap-plotting/

I can generate a heatmap using this method, but would like to alter the
scale.  I would like it so that I can have a little more complex gradient
ranging from 0% to the highest relative abundance that I observe in the
above table (65.1%).  The default scale I get using the link above is just a
relative intensity scale ranging from 1 to 5 (where white represent low
percentages and steelblue represented high percentages).  This is alright
but for phyla that are present at relative abundance of less than 5% all
appear to be white (or non-existant).  Is there anyway to fix this?  Any
help would be greatly appreciated.

Thanks,

Chris