1. Supplemental data 1. Correspondence between Ensembl genes and proteins accession numbers

2. Supplemental Data 2. Chicken FFAR2 expression in embryonic tissue, liver and adipose tissue using RNA-Seq data. Ensembl gene IDEnsembl transcript IDEmbryosLiverAdipose tissue ENSGALG00000009351ENSGALT0000001522871812 ENSGALG00000011647ENSGALT000000190361829 ENSGALG00000012141ENSGALT000000198331316 ENSGALG00000022027ENSGALT0000003557713434 ENSGALG00000022066ENSGALT0000003560763729 ENSGALG00000022260ENSGALT000000358243053 ENSGALG00000022360ENSGALT0000003594138806 ENSGALG00000022422ENSGALT0000003600111530 ENSGALG00000022513ENSGALT0000003608917412 ENSGALG00000022560ENSGALT000000284480213 ENSGALG00000022595ENSGALT00000036173862163 Total reads 1475166132 Values are the read sum of either liver and adipose of eight 15 weeks old birds or twenty 4.5-day embryos. Filtering criterion of 10 reads was used to identify expressed genes (in pink).

3. Supplemental Data 3. Percentage of identity between nucleic acids between chicken FFAR-2 paralogs After multiple sequences alignment using CLUSTAL O(1.2.1), the Percent Identity Matrix was created by Clustal2.1. A high degree of sequence identity (>80% in green and >90% in pink) is observed between the FFAR2 paralogs (annotated as “Novel Ensembl prediction” in the Ensembl database (Genome assembly WASHUC2 (Ensembl release 70)). Red boxes correspond to the highest scores (> 98.5%).

4. Supplemental Data 4. Free fatty acid receptors accession number in human, mouse, chicken and pig species HumanMouseChickenPig Gene name Gene description Ensembl Gene ID Ensembl Transcript ID Ensembl Gene ID Ensembl Transcript ID Ensembl Gene ID Ensembl Transcript ID Ensembl Gene ID Ensembl Transcript ID FFAR2 (GPR43) free fatty acid receptor 2 ENSG00000126262 ENST00000599180 ENSMUSG00000051314 ENSMUST00000053156 26 genes (See Supplemental data 1) ENSSSCG00000002881ENSSSCT00000003183 ENST00000246549ENSMUST00000168528 ENSMUST00000186339 ENSMUST00000186534 ENSMUST00000186059 ENSMUST00000163504 FFAR3 (GPR41) free fatty acid receptor 3 ENSG00000185897 ENST00000327809ENSMUSG00000019429ENSMUST00000094583 ENSSSCG00000002891ENSSSCT00000003195 ENST00000594310 ENSMUST00000185748 FFAR1 (GPR40) free fatty acid receptor 1 ENSG00000126266ENST00000246553ENSMUSG00000044453ENSMUST00000052700 ENSSSCG00000002892ENSSSCT00000003196 FFAR4 (GPR120, O3FAR1) free fatty acid receptor 4 ENSG00000186188ENST00000371481ENSMUSG00000054200ENSMUST00000067098ENSGALG00000026733ENSGALT00000045426ENSSSCG00000010478ENSSSCT00000011466 ENSG00000186188ENST00000371483

5. Supplemental Data 5. Percentage of identity between nucleic acids FFAR sequences of human (A), mouse (B) and pig species (C). A B Gene nameEnsembl gene IDTranscript ID 1234567891011 1 FFAR2ENSG00000126262 ENST00000599180100.0 2 ENST00000246549100.0 3 FFAR3ENSG00000185897 ENST0000032780953.053.6100.0 4 ENST0000059431055.056.496.8100.0 5 GPR42ENSG00000126251 ENST0000045497152.953.599.396.2100.0 6 ENST0000059721455.056.496.299.496.8100.0 7 FFAR1ENSG00000126266 ENST0000024655343.743.644.247.544.147.3100.0 8 FFAR4ENSG00000186188 ENST0000037148133.533.333.635.133.735.235.4100.0 9 ENST0000037148333.933.733.534.933.634.935.6100.0 10 GPR84ENSG00000139572 ENST0000026701534.1233.83635.83635.835.435.936.1100 11 ENST0000055180934 35 36 96100 Gene nameEnsembl gene IDTranscript ID 1234567891011 1 FFAR2ENSMUSG00000051314 ENSMUST00000186534100.0 2 ENSMUST0000018605989.5100.0 3 ENSMUST0000016350490.0100.0 4 ENSMUST0000005315676.684.995.7100.0 5 ENSMUST0000016852884.188.094.890.6100.0 6 ENSMUST0000018633993.692.594.290.896.6100.0 7 FFAR3ENSMUSG00000019429 ENSMUST0000009458354.054.350.550.353.854.0100.0 8 ENSMUST0000018574848.951.953.052.352.052.696.5100.0 9 FFAR1ENSMUSG00000044453ENSMUST0000005270045.145.842.5 41.443.643.242.7100.0 10 FFAR4ENSMUSG00000054200ENSMUST0000006709842.040.738.438.837.840.9 40.535.5100.0 11 GPR84ENSMUSG00000063234ENSMUST0000007982441.642.337.536.638.540.737.037.339.436.6100.0 Gene nameEnsembl gene IDTranscript ID 1 2 345 1 FFAR2ENSSSCG00000002881ENSSSCT00000003183100.0 2 ENSSSCG00000024282ENSSSCT0000003035278.2100.0 3 FFAR3ENSSSCG00000002891ENSSSCT0000000319556.157.7100.0 4 FFAR1ENSSSCG00000002892ENSSSCT0000000319647.845.949.5100.0 5 FFAR4ENSSSCG00000010478ENSSSCT0000001146644.943.045.241.2100.0 C The percentage of identity was determined using Clustal Omega version 2.1. High degree of sequences identity (>80%) is colored in pink. Red boxes correspond to the highest scores (> 98.5%). Other FFAR2 paralogs ((human F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR4,GPR68,and P2RY8) and (mouse F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR65 and GPR84) and (pig F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR4 and GPR68)) shared <50% identity with FFAR2 sequences.

6. Supplemental Data 6. Percentage of identity of amino acids FFAR sequences of human (A), mouse (B) and pig species (C). Gene nameEnsembl gene IDTranscript ID 1234567891011 1 FFAR2ENSG00000126262 ENST00000599180100 2 ENST00000246549100 3 FFAR3ENSG00000185897 ENST0000032780941 100 4 ENST0000059431041 100 5 GPR42ENSG00000126251 ENST0000045497141 98 100 6 ENST0000059721441 98 100 7 FFAR1ENSG00000126266ENST0000024655328 31 100 8 FFAR4ENSG00000186188 ENST0000037148117 19 15100 9 ENST0000037148317 19 15100 10 GPR84ENSG00000139572 ENST0000026701519 21 182019100 11 ENST0000055180919 21 182019100 A Gene nameEnsembl gene IDTranscript ID 1234567891011 1 FFAR2ENSMUSG00000051314 ENSMUST00000186534100.0 2 ENSMUST00000186059100.0 3 ENSMUST00000163504100.0 4 ENSMUST00000053156100.0 5 ENSMUST00000168528100.0 6 ENSMUST00000186339100.0 7 FFAR3ENSMUSG00000019429 ENSMUST0000009458343.1 44.646.447.343.1100.0 8 ENSMUST0000018574843.1 44.646.447.343.1100.0 9 FFAR1ENSMUSG00000044453ENSMUST0000005270029.3 30.132.433.129.330.2 100.0 10 FFAR4ENSMUSG00000054200ENSMUST0000006709822.8 21.524.825.022.823.0 16.3100.0 11 GPR84ENSMUSG00000063234ENSMUST0000007982422.6 24.226.127.122.621.9 18.622.1100.0 B Gene nameEnsembl gene IDTranscript ID 1 2 345 1 FFAR2ENSSSCG00000002881ENSSSCT00000003183100.0 2 ENSSSCG00000024282ENSSSCT0000003035273.7100.0 3 FFAR3ENSSSCG00000002891ENSSSCT0000000319541.044.7100.0 4 FFAR1ENSSSCG00000002892ENSSSCT0000000319630.328.331.7100.0 5 FFAR4ENSSSCG00000010478ENSSSCT0000001146619.217.219.115.5100.0 C The percentage of identity was determined using Clustal Omega version 2.1. The percentages of amino acid identity >67% is colored in pink. Red boxes correspond to the highest scores (100%). Other FFAR2 paralogs ((human F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR4,GPR68,and P2RY8) and (mouse F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR65 and GPR84) and (pig F2R,F2RL1,F2RL2,F2RL3,GPR132,GPR4 and GPR68)) shared <50% identity with FFAR2 sequences.

7. Supplemental Data 7. Multiple amino-acid sequence alignment of the 26 FFAR2 paralogs

10. Supplemental Data 8. FFAR2 fragment amplified with universal primers. 100pb 50pb 63pb

11. Supplemental Data 9. Gene conversion results The colors correspond to the results of the three different p-values calculated by Geneconv. Yellow: one significant p-value out to three, orange: two significant p-values, and red: the three p-values are significant. The coordinates of the fragments are indicated for each event and correspond to the codon multiple sequences alignment coordinates.

12. Supplemental Data 10. Alignment of the sequences of the human proteinase-activated receptor 1 (PAR1; pdb 3vw7; Zhang et al. 2012) and of chicken FFAR2 (ENSGALP00000034780). Secondary structures, as observed in the experimental 3D structure of PAR1, are reported above the alignment. Amino acid critical for the FFAR2 function, as depicted in Supplemental Data 4 and in Figure 3, are reported in grey, whereas amino acids under positive selection are reported in pink and orange, respectively. The position of T4 lysozyme (T4L), inserted within intracellular loop 3 to allow crystallization, is boxed in yellow.