As oceans undergo major changes due to human activities, understanding how animals and plants adapt to a changing environment is now more than ever one of the biggest questions in marine biology. To predict future responses, we can explore the past and use geological events, which provide valuable insights into adaptive mechanisms because these events were major drivers of evolution. The formation of the Isthmus of Panamá, for example, separated a previous, ancient ocean and all of its marine life into the Pacific Ocean and the Caribbean Sea. These two oceans have developed into very different habitats. Closely related populations that were separated by the Isthmus either went extinct or had to adapt to diverging environmental conditions. Therefore, the Isthmus system offers an ideal opportunity to explore drivers and processes of speciation, diversification, and adaptation through a convergent evolution framework. Microorganisms, e.g., archaea, bacteria, viruses, or fungi, play a major role in host responses to environmental change because they can have significant effects on host health and fitness.

I am studying the convergent evolution of a group of closely related hosts and their associated bacteria on both sides of the Isthmus of Panamá. I am comparing lucinid clam populations (Lucinidae) and their endosymbiotic bacterial chemosymbionts (Candidatus Thiodiazotropha) at the genomic and transcriptomic level across the Isthmus. In doing so, I will learn how a dramatic allopatric speciation event affected host-microbe associations from genotype to phenotype, and it might help me predict how such animal microbial symbioses will adapt in the future.

For this project, I am collaborating with several researchers at the Smithsonian Tropical Research Institute including Matthieu Leray, William Wcislo, Owen McMillan, Alexandra Hiller, and David Kline. I am also collaborating for with Dumas Galvez at the University of Panamá and Yolanda Camacho at the University of Costa Rica.

Here are a few impressions I made during my first trip to Panamá, accompanied by my family!

You can also check out our project blog and the summary of our first workshop in 2018 and impressions of our second workshop in 2019. Both workshops were organized by Matthieu Leray and myself and sponsored by the Gordon & Betty Moore Foundation. Jarrod Scott, the third founding postdoc in our group is building an incredibly beautiful website for us at the moment: https://istmobiome.rbind.io/

One of our first publications – The gut microbiome stability of a butterflyfish is disrupted on severely degraded Caribbean reef habitats – is described on this website. The corresponding manuscript is submitted and currently under review.

In 2019, we published a Perspective paper on the importance of host-associated microbiomes on ecosystem functioning and stability. Host-associated microbiomes drive structure and function of marine ecosystems. Short abstract: The significance of symbioses between eukaryotic hosts and microbes extends from the organismal to the ecosystem level and underpins the health of Earth’s most threatened marine ecosystems. Despite rapid growth in research on host-associated microbes, from individual microbial symbionts to host-associated consortia of significantly relevant taxa, little is known about their interactions with the vast majority of marine host species. We outline research priorities to strengthen our current knowledge of host–microbiome interactions and how they shape marine ecosystems. We argue that such advances in research will help predict responses of species, communities, and ecosystems to stressors driven by human activity and inform future management strategies.