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bioRxiv · 10.1101/261958

Two levels of host-specificity in a fig-associated Caenorhabditis

Woodruff, G. C.·Phillips, P. C.
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Abstract

BackgroundBiotic interactions are ubiquitous and require information from ecology, evolutionary biology, and functional genetics in order to be completely understood. However, study systems that are amenable to investigations across such disparate fields are rare. Figs and fig wasps are a classic system for ecology and evolutionary biology with poor functional genetics; C. elegans is a classic system for functional genetics with poor ecology. In order to help bridge these disciplines, here we describe the natural history of a close relative of C. elegans, C. sp. 34, that is associated with the fig Ficus septica and its pollinating Ceratosolen wasps.\n\nResultsTo understand the natural context of fig-associated Caenorhabditis, fresh F. septica figs from four Okinawan islands were sampled, dissected, and observed under microscopy. C. sp. 34 was found in all islands where F. septica figs were found. C. sp. 34 was routinely found in the fig interior and almost never observed on the outside surface. Caenorhabditis was only found in pollinated figs, and C. sp. 34 was more likely to be observed in figs with more foundress pollinating wasps. Actively reproducing C. sp. 34 dominated younger figs, whereas older figs with emerging wasp progeny harbored C. sp. 34 dispersal larvae. Additionally, C. sp. 34 was observed dismounting from plated Ceratosolen pollinating wasps. C. sp. 34 was never found on non-pollinating, parasitic Philotrypesis wasps. Finally, C. sp. 34 was only observed in F. septica figs among five Okinawan Ficus species sampled.\n\nConclusionThese observations suggest a natural history where C. sp. 34 proliferates in young F. septica figs and disperses from old figs on Ceratosolen pollinating fig wasps. The fig and wasp host specificity of this Caenorhabditis is highly divergent from its close relatives and frames hypotheses for future investigations. This natural co-occurrence of the fig/fig wasp and Caenorhabditis study systems sets the stage for an integrated research program that can help to explain the evolution of interspecific interactions.

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Woodruff, G. C., Phillips, P. C.. 2018-02-13. Two levels of host-specificity in a fig-associated Caenorhabditis. https://doi.org/10.1101/261958

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