title: Biodiversity and multifunctionality in a microbial community: a novel theoretical approach to quantify functional redundancy.
abstract: Ecosystems have a limited buffering capacity of multiple ecosystem functions against biodiversity loss (i.e. low multifunctional redundancy). We developed a novel theoretical approach to evaluate multifunctional redundancy in a microbial community using the microbial genome database (MBGD) for comparative analysis. In order to fully implement functional information, we defined orthologue richness in a community, each of which is a functionally conservative evolutionary unit in genomes, as an index of community multifunctionality (MF). We constructed a graph of expected orthologue richness in a community (MF) as a function of species richness (SR), fit the power function to SR (i.e. MF = cSR(a)), and interpreted the higher exponent a as the lower multifunctional redundancy. Through a microcosm experiment, we confirmed that MF defined by orthologue richness could predict the actual multiple functions. We simulated random and non-random community assemblages using full genomic data of 478 prokaryotic species in the MBGD, and determined that the exponent in microbial communities ranged from 0.55 to 0.75. This exponent range provided a quantitative estimate that a 6.6-8.9% loss limit in SR occurred in a microbial community for an MF reduction no greater than 5%, suggesting a non-negligible initial loss effect of microbial diversity on MF.
authors.affiliation: Institute of Oceanography, National Taiwan University, , Number 1, Section 4 Roosevelt Road, Taipei 10617, Taiwan, Republic of China, Center for Marine Environmental Studies (CMES), Ehime University, , 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan, Laboratory of Environmental Biological Science, Faculty of Science and Technology, Kinki University, , 3-4-1 Kowakae Higashiosaka, Osaka 577-8502, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miki
authors.forename: Taichi
authors.initials: T
authors.lastname: Yokokawa
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Matsui
mesh_terms: D044822:Biodiversity; D003198:Computer Simulation; D064307:Microbiota / Q000235:genetics* / Q000502:physiology; D008954:Models, Biological; D013045:Species Specificity
keywords: accumulation curve; ecosystem function; microbial diversity; multifunctional redundancy; orthologue richness; species loss