Found inside the healthy leaf tissue of every plant species yet examined, foliar fungal endophytes have been shown to play a critical role in mediating how hosts interact with their abiotic environment and with other organisms. Though invisible to the naked eye, endophytic fungi form ubiquitous and hyperdiverse communities spanning hundreds of millions of years of evolutionary history. It is suspected that these cryptic symbionts comprise a large portion of the estimated 98% of fungal species diversity that remains undocumented.
Combining culture-based methods, next-generation environmental sequencing and stored banks of genomic DNA from critically endangered (and extinct) species, we plan to survey foliar fungal endophyte communities from every habitat on each major island in the Hawaiian archipelago, including at least a single representative of most of the 165 native eudicot genera. Plants from two of Hawaii’s most species-rich adaptive radiations will be sampled near-completion to enable insight into evolutionary aspects of host-symbiont dynamics.
Ultimately we hope to develop phylogenetic hypotheses for Hawaiian endophytic fungi and their plant hosts in order to study the evolution of specificity among endemic symbionts.
Despite the longstanding dogma that “everything is everywhere, but the environment selects” in microbial biogeography, very few studies have actually tested this directly. Our work examines the roles that reproductive strategy, dispersal limitation and environmental selection (such as temperature or moisture tolerance) play in shaping population structure, species ranges and community composition. We’ve worked at scales ranging from centimeters to continents, including the oceans between them.
While researchers have focused considerable attention on fungal symbioses in terrestrial systems, marine fungal symbioses have remained largely unexamined. Corals have long been portrayed as a model mutualistic symbiosis consisting in a colonial invertebrate and a photosynthetic dinoflagellate. Our recent research has shown that microbial diversity within corals contains a surprisingly high diversity fungi that are distinct from those located in the adjacent water column. We are interested in how these fungal communities are structured and whether they mediate the interaction between the coral and warming oceans.
Achatinella mustelina is one of several tree snail species in an genus endemic to Oahu that make up a spectacular adaptive radiation. Multiple labs and agencies are working to conserve this species via predator exclosures, captive breeding programs and population modeling. We are using high-throughput sequencing technology to assess the fungal diet of this species, and how this varies across sites and among host plants.