The aphid microbiome: ecological and evolutionary dynamics of multispecies interactions

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All organisms face a multitude of environmental threats and have to adapt to overcome these challenges. Many insects get help from an unexpected source -bacterial symbionts that live inside their bodies. These endosymbionts can have major effects on their host's biology, from allowing the host insect to feed on unbalanced diets, to protecting it from extreme temperatures and preventing death after attack by natural enemies. Under suitable conditions, a newly acquired symbiont can rapidly spread through an insect population and alter the insects' interactions with other species and the environment. This can potentially have wide-reaching consequences, particularly if the host insect is an agricultural pest or a vector of disease.Very often a host carries more than one symbiont species and in these coinfections, the presence of one symbiont can alter the ecological effects of another. Coinfections can also be costly to the host as several species of symbionts are likely to consume more resources than one.There is some evidence that coinfections are less stable than infections with single symbionts, but very little is known about the long-term effects of coinfections.In this project, we will use the pea aphid, Acyrthosiphon pisum, where seven species of symbionts are known. The phenotypic effects of several of these symbionts are well characterized, which allows us to make specific predictions about the dynamics and composition of coinfections.The student will conduct experimental evolution experiments to investigate how different environmental conditions will affect the outcome of competition between symbionts, which has the potential to not only affect the host but also to affect interacting species. For example if a symbiont that is providing resistance to a natural enemy is lost due to within host competition the natural enemy will benefit. The experimental evolution experiments will be followed by genomic analyses to identify candidate genes and pathways that are involved in bacterial interactions in coinfections and in providing ecological benefits to thehost.The student will therefore have the opportunity to study the mechanisms of the maintenance of a symbiosis and of its ecological consequences and will be trained in a wide range of entomological, genomic and bioinformatics techniques.Keywords for FindaPhD site Ecology & Conservation