Fig 1.
Colonization of a Cecropia sp. domatium.
(a) Parenchyma (white tissue) of the inner domatium wall. The part from where it has been scraped off is marked with a circle; (b) An Azteca xanthochroa queen with a parenchyma pile inoculated with chaetothyrialean fungi (foundress patch). Eggs and larvae are deposited next to the fungal patch (circle); (c) Detail of an Azteca constructor foundress patch with hyphae and (d) conidiophores (arrowheads). Scale bars: (a) 2cm, (b) 2mm.
Fig 2.
Molecular phylogenetic analysis of fungal genotypes associated with patches from Azteca foundress queens.
A maximum likelihood analysis of the ITS matrix was performed with MEGA7 [36], showing the best tree (-lnL = 1906.92) based on the Kimura 2-parameter (K2) model [37], applying a discrete Gamma distribution (+G; 5 categories, parameter = 0.4209) and a proportion of evolutionarily invariable sites (+I; 41.37% sites). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Bold branches indicate ML bootstrap support above 50%.
Table 1.
Comparison of genotype and OTU (operational taxonomic unit) occurrence in foundress queen patches (FP n = 52) and patches of established colonies (EP n = 54).
The number represents how often the genotype was found in the respective ant species (in %) relative to all samples of the respective ant species. In nine patches, more than one genotype was detected (n = 9 for queen and established patches). In eleven domatia, more than one founding queen occurred (up to 10). Genotype frequency is shown for each Azteca species separately. In some cases, the percentage exceeds 100% due to patches with more than one fungal OTU.
Fig 3.
Frequency of patches with one or multiple fungal OTUs in foundress queen patches compared to established colonies.
In domatia with a single queen patches with only one OTU is common, whereas in multiqueen domatia with several queens of the same species as well as of different species multi-OTU patches are equal to those with only one OTU.
Table 2.
Number of OTUs in patches of individual established colonies compared with patches of foundress queens.
For foundress queen samples, it is indicated whether we found (i) a single queen (1 Q), (ii) more than one of the same Azteca species (>1 Q same sp.) or (ii) more queens of different Azteca species (>1 Q diff spp.) in one domatium.
Fig 4.
Infrabuccal pocket content of founding queens.
Founding queens (a) carry in their infrabuccal pockets (b) hyphae, (c) a number of unclassified particles, and (d) nematode dauerlarvae. Infrabuccal pocket content was stained with calcofluor white and investigated with an excitation of 365 nm (b, c) and brightfield (d). Scale bars: (b, c) 10μm, (d) 20μm.
Fig 5.
15N incubation of foundress patch.
δ15N values of founding queens, larvae and pupae after incubating the patches of the respective founding queen for 7 days with a 15N labelled amino acid mix. 15N accumulation could be shown for pupae and larvae, but only larvae were significantly enriched. The δ15N values of foundress queens from labelled patches did not differ from natural abundance. Hyphae were thus not eaten by the queens themselves but fed to the larvae.
Table 3.
Mean δ15N and C/N ratio of foundress queen patches from domatia with 15N amino acid mix labelled patches and unlabelled ones.
SE gives the standard error of means, n the sample number size.