Speaker
Description
Symbionts are widespread across ecosystems and play fundamental roles in host biology. Over evolutionary time, some symbionts shift from one host species to another, where they must survive, transmit, and adapt to a novel host environment. However, we still have a limited understanding of how symbionts establish in new hosts, how rapidly they adapt, and how their effects on host fitness change during this process.
Here, we used Spiroplasma, a maternally transmitted bacterial symbiont found in approximately 10% of insect species, as a model to study symbiont evolution during host shifts. Using an experimental evolution approach, we transinfected Spiroplasma into novel Drosophila hosts and maintained replicated host–symbiont lines for 35 host generations under constant temperature and humidity. To assess changes in symbiont adaptation, we compared host fitness-related traits at the beginning and end of the experiment, including fecundity, longevity, and protection against parasitoid wasps.
To link phenotypic changes with genomic evolution, we performed in-house whole-genome sequencing using both Nanopore and Illumina platforms and analysed genetic variation between the ancestral symbiont population and symbionts coevolved in novel hosts. As Spiroplasma is imperfectly transmitted from mother to offspring, we also quantified symbiont density and vertical transmission rate across host generations. Together, these data allow us to track how a symbiont transfers into a novel host, establishes within host populations, and potentially adapts over experimentally observable timescales.
This study asks whether symbiont evolution, often considered over deep evolutionary time, can be directly observed within a human lifetime.
| Status Group | Doctoral Researcher |
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