Mutualisms

Mutualisms

Hassan Salem

Numerous adaptations in animals are a direct consequence of symbiotic partnerships with microorganisms. We are interested in the molecular currencies driving the cooperation of species, and the genomic and metabolic consequences of coevolution between a host and its symbiont.

Our emphasis is on the dynamic relationships that have evolved within leaf-feeding animals, focusing mainly on insects. We use leaf beetles (Coleoptera: Chrysomelidae) as a study system given the streamlined mutualisms they form with specialized symbionts possessing drastically reduced genomes and correspondingly limited metabolisms. These symbioses span a spectrum of interactions, ranging from nutritional associations where the symbiont facilitates the digestion of complex plant polymers, to protective partnerships that upgrade the defensive biochemistry of the insect host.

The widespread, and often convergent, evolution of mutualisms in leaf beetles provides a highly tractable model to characterize the molecular and biochemical currencies contributing to the origin of leaf-feeding across the Metazoa, with applications that extend to ruminants and other folivorous animal groups. Our work is integrative in nature, combining genomics and fieldwork with chemical ecology and developmental biology to understand the origin of these associations and how they facilitate adaptation in beetles. 

Press releases & research news

Symbioses and gene transfer in leaf beetles
Researchers from the Max Planck Institute for Chemical Ecology in Jena, the Max Planck Institute of Biology in Tübingen, Germany, and a consortium of international scientists explored the evolutionary success of leaf beetles, the most diverse herbivores on Earth. They showed that symbioses with bacteria have evolved repeatedly and independently in different beetle lineages, and contribute significantly to the efficient digestion of plant food. These symbiotic relationships provide clues as to how genetic material was exchanged between bacteria and beetles. more
Adaptation through symbiosis, sixty-two million years of it
Brightly coloured beetles that feed on a wide range of plants possess robust metabolic capabilities, thanks to bacteria residing in specialised organs in their digestive tract. The bacterium Stammeraprovides essential enzymes enabling Cassidinae beetles to digest plant cell wall components efficiently. Researchers from the Max Planck Institute for Biology in Tübingen discovered the ancient origin of this specialised relationship. They found symbiotic leaf beetles exhibit greater species diversity than their non-symbiotic relatives. more
Plant pathogen moonlighting as an insect mutualist
Symbioses with microbes span a gradient of interaction outcomes across the mutualism-to-parasitism continuum. But how stable are these designations? Are mutualists beneficial under all conditions? And are parasites destined to always harm their hosts? more
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