Table 1. References for processes or functions which are supported by rare microbes.

Process or function	References
Biochemical processes
Sulfate reduction	Pester et al., 2010
	Loy and Pester, 2010
	Steger et al., 2011
Methane consumption	Bodelier et al., 2013
Carbon cycling
Substrate use	Franklin et al., 2001
	Matos et al., 2005
	Hernandez-Raquet et al., 2013
	Mallon et al., 2015
Straw decomposition	Griffiths et al., 2001
	Baumann et al., 2013
Nitrogen cycling
Nitrification	Griffiths et al., 2004
Nitrogen uptake	Musat et al., 2008
Denitrification	Philippot et al., 2013
Fixation	Hua et al., 2015
Pollutant degradation
2,4,6-trichlorophenol	Sanchez et al., 2004
	Dell'Anno et al., 2012
Petroleum hydrocarbons	Giebler et al., 2013
Phenanthrene mineralization	Hernandez-Raquet et al., 2013
Triclosan, microcystin-LR	Delgado-Baquerizo et al., 2016
Community assembly	Yan et al., 2015
Resistance to invasion	Garland et al., 1999
	Matos et al., 2005
	Van Elsas et al., 2012
	Vivant et al., 2013
	Mallon et al., 2015
Resilience	Griffiths et al., 2004
	Tardy et al., 2014
Microbiome
Human health
Lung infection	Van der Gast et al., 2011
Periodontal disease	Hajishengalllis et al., 2011
Gut microbiota	Stecher et al., 2013
Plant health
Plant biomass, herbivores	Hol et al., 2010
Plant biomass	Hol et al., 2015a
Plant pathogens	Hol et al., 2015b

Background information for Figure 2.