Fig. 9
From: Evolution of vertebrate nicotinic acetylcholine receptors
a Duplication scheme of the nAChR genes following 1R + 2R. Ten nAChR genes in five different paralogons are present in the vertebrate predecessor. Following 1R + 2R the repertoire expands to 19 genes. Human retained 16 genes (lacking CHRNA11, CHRNA8 and CHRNB5), chicken 15 (lacking CHRNA11, CHRNB5, CHRNB1 and CHRNE) and spotted gar 18 (lacking CHRNB2), plus the CHRNB1.2 local duplication. b Duplication scheme of the nAChR genes following 3R. 20 nAChR genes are present in the teleost predecessor, following 3R the repertoire expands to 31 genes. Zebrafish has retained 27 genes. Crosses indicate gene loss or gene not yet identified