Amend Lab | Univ of Hawaii

Research

I. Diversity and Evolution of Fungal Endophytes in Native Hawaiian Plants

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,  environmental sequencing and stored banks of genomic DNA from critically endangered (and extinct) species, we conduct surveys foliar fungal endophyte communities from every habitat on each major island in the Hawaiian and Vanuatu archipelagos.

Ultimately we hope to develop phylogenetic hypotheses for Pacific endophytic fungi and their plant hosts in order to study the evolution of specificity among endemic symbionts. We are also exploing how endophytes interact with their hosts to impact health and disease resistance.

Hawaiian plantHawaiian plant

II. Biogeography of Small Organisms

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. 

pink flowersplant

 

Habit Connectivity and Microbial Resevoirs

Acquiring the “right” microbiome at the “right” time is essential, since an organism’s accessory microbiome plays nearly as large a role in determining an organism’s health and fitness as does that organism’s genes. However the process governing microbiome formation is more complexed and less understood. Where, then, is the source of these beneficial microbes that are so critical for human and ecosystem services? How does the environment shape microbiomes? How does the environment shape host and ecosystem function via microbiomes? 

To address these questions we have established the first ecosystem microbiome observatory in the Waimea valley on Oahu's North Shore.  In fewer than 8 km, the main rivers of Waimea valley plunge from a high elevation rain forest, over cascading waterfalls, into a protected estuary and out over one of the most pristine coral reefs on Oahu. This short span represents a steep elevation and precipitation gradient, ranging from over 5 m of rainfall at the river’s headwaters to around 1 m at the coast. This offers a wide diversity of terrestrial, riverine and marine habitats in close proximity to each other. Within a series of plots in each of these habitats, we are surveying approximately 70 organisms and substrates to gain a sense microbiol source and sink dynamics at a landscape level.  Additional manipulation experiments assess how the environment and microbiome interact to effect host health and fitness.   
 

Diversity and Distribution of Marine Fungi

Fungi are critical, though largely overlooked, member of marine microbial communities.  Through various lab projects and collaborations we are exploring the diversity and distributions of marine fungi on a global scale, as well as their roles in host health and ecosystem processes like nutrient cycling. Corals, algae, seagrasses and sediments are some of our focal habitats so far.

Data Download

Coral-associated marine fungi form novel lineages and heterogeneous assemblages

Data published in ISME Journal, 2012

Download file

Indoor fungal composition is geographically patterned and more diverse in temperate zones than in the tropics

Data published in PNAS, 2010

Download file