Abstract
The eukaryotic microbiome of “lower” termites is highly stable and host-specific. This is due to the mutually obligate nature of the symbiosis and the direct inheritance of protists by proctodeal trophallaxis. However, vertical transmission is occasionally imperfect, resulting in daughter colonies that lack one or more of the expected protist species. This phenomenon could conceivably lead to regional differences in protist community composition within a host species. Here, we have characterized the protist symbiont community of Heterotermes tenuis (Hagen) (Blattodea: Rhinotermitidae) from samples spanning South and Central America. Using light microscopy, single cell isolation, and amplicon sequencing, we report eight species-level protist phylotypes belonging to four genera in the phylum Parabasalia. The diversity and distribution of each phylotype’s 18S rRNA amplicon sequence variants (ASVs) mostly did not correlate with geographical or host genetic distances according to Mantel tests, consistent with the lack of correlation we observed between host genetic and geographical distances. However, the ASV distances of Holomastigotoides Ht3 were significantly correlated with geography while those of Holomastigotoides Ht1 were significantly correlated with host phylogeny. These results suggest mechanisms by which termite-associated protist species may diversify independently of each other and of their hosts, shedding light on the coevolutionary dynamics of this important symbiosis.
Highlights
The degree of intraspecific variation in the insect gut microbiota varies greatly among lineages
We identified four genera of protists, all belonging to the phylum Parabasalia: Pseudotrichonympha, Cthulhu, Cononympha, and Holomastigotoides (Figure 1)
Each of these genera had been previously reported to inhabit the gut of H. tenuis, though Cononympha was previously known as Microspironympha or Spirotrichonympha (Mackinnon, 1926, 1927; de Mello, 1954; Saldarriaga et al, 2011; James et al, 2013)
Summary
The degree of intraspecific variation in the insect gut microbiota varies greatly among lineages. Many insects, including butterflies and walking sticks, have such highly variable gut microbial communities that it has been argued they have no specific microbiome (Shelomi et al, 2013; Hammer et al, 2019; Ravenscraft et al, 2019). This high variability likely stems from molting, Heterotermes tenuis Symbionts which disrupts the gut microbiota, and from the lack of a mechanism for vertical transmission of microbes. Termites exhibit relatively stable and largely co-diversifying gut microbial communities (Bourguignon et al, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
