COS 30-5
The invasive provenance hypothesis: positive genotype-environment interactions are a major driver of invasions

Tuesday, August 12, 2014: 9:20 AM
Golden State, Hyatt Regency Hotel
Rafael D. Zenni, Ecology and Evolutionary Biology, The University of Tennessee, Knoxville, TN
Joseph K. Bailey, Ecology and Evolutionary Biology, The University of Tennessee, Knoxville, Knoxville, TN
Daniel Simberloff, Ecology and Evolutionary Biology, The University of Tennessee, Knoxville, TN

Human-mediated introductions can provide valuable insights on how organisms respond to climate change and novel interactions. Researchers are often able to explain invasions after they happen, but predictive abilities remain limited. Two explanations for this limitation are the predominant focus on species-level variation and the heavy reliance on correlative instead of mechanistic models. For this study, we measured the invasive range expansion of loblolly pine genetic provenances across six replicated common gardens planted in 1973 along 6° of latitude in southern Brazil. Examining the generational progress of the invasion front over 40 years allowed us to study changes in allele frequencies from the introduced pool to the leading edge of the invasion front in response to different selective pressures posed by each common garden’s environment. We hypothesized that local adaptation occurring over millennia in the native range of loblolly (southeast USA) would affect the invasive potential of provenances in the introduced range. We predicted that genetic provenances would successfully invade only at locations with abiotic conditions similar to those of the provenances’ native range. To test this prediction, we genotyped 50 plants from each naturalized population and assigned them to their native genetic provenance. 


We found three genetic provenances introduced in the common gardens; plants originating from the coastal plains (coastal provenance), plants originating from the Gulf region (central provenance), and plants from west of the Mississippi (Texas provenance). In the introduced locations, provenances responded differently to the climate of each location, mostly responding to temperature and precipitation differences. Strikingly, the temperature and precipitation ranges where provenances were invasive did not match the values from their native ranges. For example, plants from the Texas provenance were better adapted and most invasive in regions with mean annual temperatures below 16.5° C and annual precipitations above 1,500 mm, whereas the coastal provenance appeared better adapted and most invasive where mean annual temperature is above 19° C and annual precipitation is below 1,300 mm. This is evidence that provenances can occupy climate niches different from those observed in their native ranges and that niches could be inferred more precisely at genotypic levels. Our results constitute a unique empirical demonstration of fine-scale rapid evolution during invasive range expansions that is largely determined by provenance-environment interactions. Moreover, this study can help researchers outline mechanistic approaches to predict the invasive potential of genotypes at specific locations.