Abstracts (first author)


Facultative symbionts as a eukaryotic horizontal gene pool

Author(s): Henry LM


Facultative or ‘secondary’ bacterial symbionts are very common in eukaryotes, particularly insects. While not essential, they often provide beneficial functions that can profoundly affect host biology. It has been hypothesised that secondary symbionts may form a “horizontal gene pool” shuttling adaptive genes amongst lineages in an analogous manner to plasmids and other mobile genetic elements in bacteria. However, the viability of this hypothesis rests upon a key unknown. We do not know if the distributions of symbionts across host populations reflect random acquisitions followed by maternal inheritance, or if the associations have occurred repeatedly in a manner that is consistent with a dynamic horizontal gene pool from which adaptations can be readily gained and lost in response to environmental changes. Here we test the importance of horizontal transfer using the phylogenetic and ecological distributions of secondary symbionts carried by 1104 pea aphids collected from 14 countries and 11 plant-associated populations. This reveals that not only is horizontal transfer common, it is associated with aphid lineages colonizing new ecological niches, such as switching to novel host plants or moving into new climatic regions. Moreover, aphids that share the same ecologies in different regions worldwide have independently acquired related symbiont genotypes, suggesting a central role of the symbionts in their host’s niches. In sum, our data reveals symbiont populations are dynamic with their distributions shaped by horizontal transmission and differential retention amongst aphid lineages, both of which are strongly influenced by ecological factors. We conclude that the secondary symbiont community forms a horizontal gene pool that is central to the adaptation and distribution of their insect hosts


Chairman: Octávio S. Paulo
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XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon


Computational Biology & Population Genomics Group