The Native Hawaiian Insect Microbiome Initiative: A Critical Perspective for Hawaiian Insect Evolution.

Gordon Bennett,Jennifer Michalski,Karl Magnacca,Jessika Santamaria,Alexander Ching,Mitchel Logan,Kirsten Poff,Joanne Yew,Curtis Ewing,Priscilla Seabourn,Heather Stever,Jesse Eiben,Sayaka Aoki,Jesse Adams,Jonathan Reil

doi:10.3390/insects8040130

Abstract

Insects associate with a diversity of microbes that can shape host ecology and diversity by providing essential biological and adaptive services. For most insect groups, the evolutionary implications of host–microbe interactions remain poorly understood. Geographically discrete areas with high biodiversity offer powerful, simplified model systems to better understand insect–microbe interactions. Hawaii boasts a diverse endemic insect fauna (~6000 species) characterized by spectacular adaptive radiations. Despite this, little is known about the role of bacteria in shaping this diversity. To address this knowledge gap, we inaugurate the Native Hawaiian Insect Microbiome Initiative (NHIMI). The NHIMI is an effort intended to develop a framework for informing evolutionary and biological studies in Hawaii. To initiate this effort, we have sequenced the bacterial microbiomes of thirteen species representing iconic, endemic Hawaiian insect groups. Our results show that native Hawaiian insects associate with a diversity of bacteria that exhibit a wide phylogenetic breadth. Several groups show predictable associations with obligate microbes that permit diet specialization. Others exhibit unique ecological transitions that are correlated with shifts in their microbiomes (e.g., transition to carrion feeding from plant-feeding in Nysius wekiuicola). Finally, some groups, such as the Hawaiian Drosophila, have relatively diverse microbiomes with a conserved core of bacterial taxa across multiple species and islands.

Highlights

All complex multicellular life evolved either in alliance with, or in defense from, microbes, which have dominated Earth for billions of years [1]
Insect species were selected to explicitly investigate (a) the microbial diversity associated with iconic Hawaiian host insects, and (b) the microbiome communities of hosts that have experienced novel niche transitions
Our results reveal that Hawaiian insects harbor a wide diversity of bacterial lineages, comprising over 10 bacterial phyla

Summary

Introduction

All complex multicellular life evolved either in alliance with, or in defense from, microbes, which have dominated Earth for billions of years [1]. In order to fully understand organismal function, diversity, and evolution, microbial interactions should be an essential consideration. A large body of literature has revealed that bacterial symbionts shape insect ecology and evolution by providing a range of environmental services, or by manipulating host reproduction [2,3]. It is well understood that microbial symbionts played fundamental roles in the diversification of some of the largest insect orders (e.g., the plant-sap feeding Hemiptera), their roles in shaping species-level diversity in most insect groups remain relatively unknown [4,5,6,7]. Efforts to comprehensively address questions regarding the role of microbes in insect ecology and evolution are hindered by the geographically widespread nature of insect populations and closely related species Recent advances in molecular sequencing technologies provide the ability to tackle these questions at unprecedented scales [8,9,10].

Methods

Results

Conclusion