Evolutionary tree of the nematode and arthropod Class 2 B1 receptors.

<p>The five distinct groups of the nematode and arthropod Class 2 B1 identified are annotated in color. The phylogenetic tree is constructed with 116 nematode and arthropod receptor sequences using the maximum likelihood method implemented in the PhyML program (v3.0 aLRT) and using the alignment of the conserved TM domains. Four sequences were not included in the analysis due to the incomplete nature of their TMs and they are indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092220#pone.0092220.s006" target="_blank">Table S1</a>. Reliability of internal branching is assessed using the bootstrapping method (100 bootstrap replicates). For simplicity, only bootstrap support nodes for the main protostome clades are represented. The complete phylogenetic tree is available as <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092220#pone.0092220.s002" target="_blank">Figure S2</a>.