Fig. 3.

The origin of denitrification in context of the whole foraminiferal group. (A) Large-scale phylogenetic representation of Peruvian foraminifera in context of different foraminiferal taxa based on 18S sequences available in public databases. Clades Ι and ΙΙΙ of the order Rotaliida are highly supported by bootstrap values. Questionable branching of Nonionella outside clade ΙΙΙ is not characteristic of data in the current study, as exemplified for N. labradorica, which also does not group directly with clade ΙΙΙ. G. pacifica forms a clade with G. auriculata but within clade ΙΙΙ. However, we consider the branching of these two species as uncertain due to the long branches and the low bootstrap support, which we did not observe for the marker protein phylogeny (Fig. 2). Lower (light purple; including N. labradorica) and higher (dark purple) boundaries for the origin of foraminiferal denitrification are highlighted by boxes. (B) Extended phylogenetic representation of foraminifera including planktonic species. Lower (light purple) and higher (dark purple) boundaries for the origin of foraminiferal denitrification are highlighted by boxes. “Planktonic Ι” and “Planktonic ΙΙΙ” designate two to three distinct clusters comprising planktonic foraminifera. Species experimentally shown to denitrify are highlighted in blue. The only exception is Stainforthia fusiformis, where denitrification activity has been shown for an unspecified species of the same genus. Species also considered in Fig. 1 or SI Appendix, Fig. S3 are marked with asterisks. Several species labels contain the contig ID and orientation of 18S sequences in the corresponding transcriptome assemblies. Bootstrap support values (≥70) with 1,000 replicates are shown at the branches. The trees were rooted by the clade of monothalamids containing R. filosa. A detailed phylogeny is presented in SI Appendix, Fig. S4.