Phylogenetic Tree and Intron Conservation Patterns

<p>(A) Phylogenetic tree of the four fungal organisms studied <i>(M. grisea, N. crassa, F. graminearum,</i> and <i>A. nidulans)</i> with estimated time scale in millions of years ago. The rooted organismal tree was constructed using an unweighted pair group method using arithmetic averages based on a concatenated alignment of 2,073 orthologous gene sets. Estimated dates of divergence from <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020422#pbio-0020422-Taylor1" target="_blank">Taylor et al. (1999)</a>, <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020422#pbio-0020422-Berbee1" target="_blank">Berbee and Taylor (2000)</a>, and <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020422#pbio-0020422-Heckman1" target="_blank">Heckman et al. (2001)</a>.(B) Classification of intron presence (+) and absence (−) patterns across the four fungal species. A blue “+” indicates a raw intron gain in the corresponding organism, a red “−” indicates a raw intron loss in the corresponding organism, a green “+” indicates a conserved intron, and all other introns are indicated in black.