Geographic mosaics of plant–soil microbe interactions in a global plant invasion

KRIKOR ANDONIAN; JOSÉ L. HIERRO; LIANA KHETSURIANI; PABLO BECERRA; GRIGOR JANOIAN; DIEGO VILLARREAL; LOHENGRIN CAVIERES; LAUREL FOX; RAGAN M. CALLAWAY

JOURNAL OF BIOGEOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2012 p. 600 - 608

0305-0270

Aim Our aim in this study was to document the global biogeographic variationin the effects of soil microbes on the growth of Centaurea solstitialis (yellowstarthistle; Asteraceae), a species that has been introduced throughout the world,but has become highly invasive only in some introduced regions.Location To assess biogeographic variation in plant–soil microbe interactions,we collected seeds and soils from native Eurasian C. solstitialis populations andintroduced populations in California, Argentina and Chile.Methods To test whether escape from soil-borne natural enemies maycontribute to the success of C. solstitialis, we compared the performance ofplants using seeds and soils collected from each of the biogeographic regions ingreenhouse inoculation/sterilization experiments.Results We found that soil microbes had pervasive negative effects on plantsfrom all regions, but these negative effects were significantly weaker in soils fromnon-native ranges in Chile and California than in those from the non-nativerange in Argentina and the native range in Eurasia.Main conclusions The differences in negative effects of microbes in this studydid not conform to the enemy-release hypothesis (ERH) because of the strongnegative effect in Argentina, where C. solstitialis is invasive, compared with Chile,where it is not. These results illustrate that factors influencing invasion may varyamong regions, creating biogeographic mosaics of interaction strengths.