Phylogenetic Maximum Likelihood tree of the somatostatin receptor gene family

<p>Published in: Ocampo Daza D, Sundström G, Bergqvist CA, Larhammar D. <em>The evolution of vertebrate somatostatin receptors and their gene regions involves extensive chromosomal rearrangements.</em> BMC Evolutionary Biology 2012, 12:231 doi:10.1186/1471-2148-12-231. Please refer to this article if using this figure.</p> <p><strong>Figure 1 Phylogenetic Maximum Likelihood tree of the somatostatin receptor gene</strong><br><strong>family.</strong> The topology is supported by a non-parametric bootstrap test with 100 replicates as<br>well as an SH-like approximate likelihood ratio test (aLRT). The tree is rooted with the<br>human kisspeptin receptor 1 sequence (not shown). Branch support (bootstrap replicates) for<br>deep divergences is shown at the nodes. All branch support values are shown in Figure S1<br>(bootstrap replicates) and Figure S2 (aLRT) (see Additional file 2). The phylogenetic tree<br>shows six well-supported subtype clusters, with the somatostatin receptor subtypes <em>SSTR2, -3</em><br>and <em>-5</em> forming one ancestral branch and the <em>SSTR1, -4</em> and <em>-6</em> receptor subtypes forming one<br>ancestral branch. This phylogenetic analysis supports the emergence of all six subtypes early<br>in vertebrate evolution, with the subsequent loss of <em>SSTR4</em> in ray-finned fishes, before the<br>divergence of the spotted gar and teleost lineages, and of <em>SSTR6</em> in the tetrapod lineage. All<br>six subtypes could be identified in the coelacanth genome. A seventh <em>SSTR2</em>-like sequence,<br>called <em>SSTRX</em> in the tree, could also be identified on the same genomic scaffold in the<br>coelacanth genome (see Additional file 1, Supplemental note 1). There are well-supported<br>teleost-specific duplicate branches of <em>SSTR2, -3</em> and <em>-5</em>, although all could not be identified in<br>all teleost genomes. These duplicates have been named <em>a</em> and <em>b</em> based on the phylogenetic<br>analysis. There is a third <em>SSTR3</em> sequence in the green puffer, called <em>SSTR3c</em> in the tree.</p> <p> </p>