MicroPhan · Rol of obligate bacterial symbiosis in the diversification of a globally distributed aphid genus
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2018-06-15 → 2020-06-14
- EU contribution
- €171,349
- Participants
- 2
- Scheme
- MSCA-IF-GF
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Results in brief
Rol of obligate bacterial symbiosis in the diversification of a globally distributed aphid genus
General context Symbioses with microbial partners have facilitated the diversification of many eukaryotes. Many insect groups have made use of the metabolic capabilities of bacteria to colonize nutrient poor environments that would otherwise be unavailable to them These bacterial symbionts are generally sheltered within insect specialized cells and transmitted from mother to offspring. Hence nutritional obligate endosymbionts can be seen as “key adaptations’ which acquisitions have spurred the diversification of insects. Nutritional endosymbioses are prominent among sap feeders (e.g. aphids, cicadas, whiteflies…) and blood feeders (e.g. lice, bedbugs..). However these obligate mutualisms have their downsides. The maternal transfer of endosymbionts causes severe bottlenecks in bacterial populations, propelling the endosymbiont genome into a process of erosion. This can reduce the metabolic capability of bacteria, ultimately increasing their insect host extinction risks. One possible outcome of this situation is the acquisition of a new symbiont . An increasing body of evidence shows that, in many insect species, a new bacterial symbiont co-exists with the primary one, taking on a subset of the functions that the eroded symbiont cannot fulfill anymore. One particularity of these bacterial partnerships is that they are extremely dynamic: the newly arrived symbiont is often replaced during the diversification of the insect hosts. This project attempts to understand the dynamic of these endosymbiotic systems. Why are these new symbiont repeatedly replaced ? Do shifts in symbiotic associations lead to ecological shifts in the insect hosts? What are the potentially negative ramifications of obligate, heritable symbioses ? Can they overcome the initial benefits of the associations? Importance New data from large metagenomics studies are fundamentally altering our understanding of animal biology. Recent syntheses underline that bacterial associations can facilitate the evolution of animals and that these also have profound effect on genome evolution of symbionts and eukaryotic associates. We have no doubt that this project will make significant advances on these fundamental topics. From an applied perspective, understanding the role of endosymbiosis in insect host-plant adaptation and climatic tolerance could be crucial for predicting their resilience to environmental changes and ultimately guide strategies for the control of agricultural pests. The overall objective of the project is to understand the role of endosymbiotic bacteria in the long-term evolution of a globally-distributed insect clade.
Data: CORDIS, © European Union
Project objective
Plant-feeding insects represent a significant part of earth biodiversity but also encompass many plant pests that cause major losses to agricultural crops. One key factor in their evolutionary success probably resides in the mutualistic associations they have established with bacteria that reside in their cells. These endosymbionts metabolize some of the nutrients lacking in their host diet and can be essential for successfully shifting to new ecological niches. However, intracellular lifestyle also often results in severe genomic erosion for endosymbionts that limits their metabolic versatility and in fine affects their host adaptive potential. In this project we aim at deciphering the role of bacterial endosymbiosis in the long-term evolution of plant-feeding insects. The main question we want to address is whether the evolution of obligate bacterial endosymbionts played a significant role in the diversification (speciation and extinction) of their hosts. Using the genome sequences of the main bacterial endosymbionts associated with a globally distributed aphid genus, we will: 1) reconstruct the history of aphid/symbiont associations by conducting phylogenomic analyses; 2) identify the footprint of selection and genetic drift in bacterial genomes by comparing patterns of molecular evolution within and between symbiotic bacterial lineages; 3) illuminate how changes in the endosymbiont community metabolic capabilities have accompanied aphids evolutionary transitions (host plant shifts, climatic tolerance, rates of speciation) using phylogenetic comparative methods. Using the data from an ongoing large sequencing project, this project will combine recent methods in phylogenomics, metabolic network analyses and the study of macroevolutionary processes. With this fellowship, the applicant will lead an exciting and innovative multidisciplinary project, supervised by international experts in microbial evolutionary genomics and insect macroevolution; this project will cre
Original text from CORDIS.
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Data: CORDIS, © European Union