title: Change the colour of ablines on ggplot
body: <p>Using <a href="http://pastebin.com/06Zwabnq" rel="noreferrer">this data</a> I am fitting a plot: </p>
  
  <pre><code>p &lt;- ggplot(dat, aes(x=log(Explan), y=Response)) + 
        geom_point(aes(group=Area, colour=Area))+
        geom_abline(slope=-0.062712, intercept=0.165886)+
        geom_abline(slope= -0.052300, intercept=-0.038691)+
        scale_x_continuous("log(Mass) (g)")+
        theme(axis.title.y=element_text(size=rel(1.2),vjust=0.2),
              axis.title.x=element_text(size=rel(1.2),vjust=0.2),
              axis.text.x=element_text(size=rel(1.3)),
              axis.text.y=element_text(size=rel(1.3)),
              text = element_text(size=13)) +
        scale_colour_brewer(palette="Set1")
  </code></pre>
  
  <p>The two ablines represent the phylogenetically adjusted relationships for each Area trend.  I am wondering, is it possible to get the ablines in the same colour palette as their appropriate area data?  The first specified is for Area A, the second for Area B.</p>
  
  <p>I used:</p>
  
  <pre><code>g &lt;- ggplot_build(p) 
  </code></pre>
  
  <p>to find out that the first colour is #E41A1C and the second is #377EB8, however when I try to use aes within the +geom_abline command to specify these colours i.e.</p>
  
  <pre><code>p &lt;- ggplot(dat, aes(x=log(Explan), y=Response)) + 
        geom_point(aes(group=Area, colour=Area))+
        geom_abline(slope=-0.062712, intercept=0.165886,aes(colour='#E41A1C'))+
        geom_abline(slope= -0.052300, intercept=-0.038691,aes(colour=#377EB8))+
        scale_x_continuous("log(Mass) (g)")+
        theme(axis.title.y=element_text(size=rel(1.2),vjust=0.2),
              axis.title.x=element_text(size=rel(1.2),vjust=0.2),
              axis.text.x=element_text(size=rel(1.3)),
              axis.text.y=element_text(size=rel(1.3)),
              text = element_text(size=13)) +
        scale_colour_brewer(palette="Set1")
  </code></pre>
  
  <p>It changes the colour of the points and adds to the legend, which I don't want to do.</p>
  
  <p>Any advice would be much appreciated!</p>