Fig. 1. Phylogenetic reconstruction illustrating the placement of H. trivolvis 5-HT receptor proteins as orthologs of 5-HT₁ and 5-HT₇ receptors in other animals. The tree illustrates the relationship between the two H. trivolvis receptors and other receptors of the 5-HT₁, 5-HT₅ and 5-HT₇ families. This figure represents a subtree of a larger phylogenetic tree generated from 768 biogenic amine receptors, aligned and trimmed to yield a matrix of 214 amino acid characters. For simplicity, clades encompassing a large number of vertebrate receptors are represented diagrammatically as triangles. Each sequence is represented by the name of the species from which it was obtained and a GenPept identification number that is uniquely assigned to each sequence. The scale bar represents an amount of evolutionary change corresponding to an expected 0.1 changes per site.