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Fig. 4 | BMC Evolutionary Biology

Fig. 4

From: Immune genes and divergent antimicrobial peptides in flies of the subgenus Drosophila

Fig. 4

The subgenus Drosophila encodes a highly divergent diptericin. a Maximum likelihood tree generated using a codon alignment of the well-conserved diptericin G domain from assembled diptericins of diverse brachyceran flies. Support values represent consensus from 100 bootstraps. Four distinct diptericin clades emerge, including three in the genus Drosophila: DptA (subgenus Sophophora), DptB (genus Drosophila), and a diptericin restricted to the subgenus Drosophila that we term DptC. b Synteny of diptericins in the genomes of sequenced drosophilids. DptA and DptC both occur upstream of DptB. We include D. neotestacea despite lacking a sequenced genome to indicate the lack of DptB recovered from the transcriptome. Diptericin B in D. guttifera is pseudogenized, and the intergenic region between DptC and DptB is listed as “>3000 bp” due to its current assembly. In S. lebanonensis, the DptA/DptC syntenic orthologue is present, but does not bear great similarity to any diptericin clade. c Summary phylogeny of Branch-site REL (BSR) analyses using only drosophilid diptericin G domains. Likelihood-ratio tests for branches with dN/dS > 1 consistently identified the branch leading to DptC as having evolved under diversifying (positive) selection (p < .05). Additional file 4: Figure S2 provides an example BSR analysis. d Amino acid alignment of the diptericin G domain from Drosophila diptericins. Numerous fixed differences are unique to each clade, particularly in the Gly22-Asp45 region. Greater conservation is observed in the Asn46-on region. The polymorphism at residue 71 described by Unckless et al. [21, 29] is indicated by a , and displays conserved differences amongst diptericin lineages in sequenced genomes

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