Duarte, S., Nobre. T., Borges, P.A.V. & Nunes, L. (2018) Symbiotic flagellate protists as cryptic drivers of adaptation and invasiveness of the subterranean termite Reticulitermes grassei Clément.Ecology and Evolution, Accepted, . DOI: (IF2016 2,440; Q2 Ecology)
Aim: Changes in flagellate protists communities of subterranean termite Reticulitermes grassei across different locations were evaluated following four predictions: i) rural endemic termite populations will exhibit high diversity of symbionts; ii) invasive urban populations, on the contrary, will exhibit lower diversity of symbionts, showing high similarity of symbiont assemblages through environmental filtering; iii) recent historical colonization of isolated regions -as the case of islands- will imply a loss of symbionts diversity; and iv) island isolation will trigger a change in colony breeding structure towards a less aggressive behavior.
Location: Portugal mainland and Faial Island from the Azores.
Methods: Symbiont flagellate protist communities were morphologically identified and species richness and relative abundances, as well as biodiversity indices, were used to compare symbiotic communities in colonies from urban and rural environments and between island invasive and mainland endemic populations. To evaluate prediction on the impact of isolation (iv), aggression tests were performed among termites comprising island invasive and mainland endemic populations.
Results: A core group of flagellates and secondary facultative symbionts was identified. Termites from rural environments showed, in the majority of observed colonies, more diverse and abundant protists communities, probably confirming prediction (i). Corroborating prediction (ii) the two least diverse communities belong to termites captured inside urban areas. The Azorean invasive termite colonies had more diverse protist communities than expected and prediction (iii) was not verified. Termites from mainland populations showed a high level of aggressiveness between neighbouring colonies, in contrast to the invasive colonies from Horta city, which were not aggressive to neighbours accordingly with prediction (iv).
Main conclusions: the symbiotic flagellate community of R. grassei showed the ability to change in a way that might be consistent with adaptation to available conditions, possibly contributing to optimization of the colonization of new habitats and spreading of its distribution area, highlighting R. grassei potential as an invasive species.