Table 1.

Positively selected residues detected with the BEB method

Foreground branch	BEB sites	Homologous position in cow paralog	Function known from homologs	SDP?
ARR0.1 sea urchins	S76	N83	Second neighboring to receptor binding residue	x
	E95	E102	-	x
	K116	K157	Low affinity IP6 binding site	x
	N121	N162	Neighboring to low affinity IP6 binding site	x
	N184	N225	Second neighboring to receptor binding residue	-
	C201	C242	Receptor binding	x
	N296	N382	Second neighboring to clathrin binding site	-
ARR0.2 sea urchins	K82	P89	Neighboring to PxxP motif	-
SAG.1 ghost shark	K2	K2	-	na
	V106	P134	Neighboring to receptor binding residue	na
	N114	R171	Phosphate sensor	na
	T128	G185	Neighboring to PxxP motif	na
	N160	G217	-	na
	H205	E262	Receptor binding	na
	Q248	N305	Second neighboring to polar core	na
	V277	T334	Second neighboring to high affinity IP6 binding site	na
	S27	G27	Second neighboring to receptor binding residue	na
SAGb teleost	V14	V35	Second neighboring to polar core	x
	R126	W194	Receptor binding	-
SAGb Acanthopterygii	P72	P93	Neighboring to PxxP motif	na
	A112	A180	Neighboring to PxxP motif	na
	D142	S210	-	na
ARR3b Euteleosteomorpha	Y42	M55	Neighboring to mu2 adaptin binding site	x
	C150	F254	Neighboring to receptor binding residue	x

The branch-site model of the PAML package was used to identify sites under positive selection in the specified foreground branch. The position in column two refers to the position within the group alignment, while the homologous position in cow serves as a reference. The position in ARR0 is given in respect to ARRB1 in cow. The function assignment is based on literature review. See Additional file 6 for further details. Positions that were also identified as specificity determining position (SDP), are marked by a cross. SDP were not determined for all subgroups as indicated by “na”