Data from: Specialist insect herbivore and light availability do not interact in the evolution of an invasive plant

Release from specialist insect herbivores may allow invasive plants to
evolve traits associated with decreased resistance and increased
competitive ability. Given that there may be genetic trade-off between
resistance and tolerance, invasive plants could also become more tolerant
to herbivores. Although it is widely acknowledged that light availability
affects tolerance to herbivores, little information is available for
whether the effect of light availability on tolerance differ between the
introduced and native populations. We conducted a common garden experiment
in the introduced range of Alternanthera philoxeroides using ten invasive
US and ten native Argentinean populations at two levels of light
availability and in the presence or absence of a specialist stem-boring
insect Agasicles hygrophila. Plant biomass (total and storage root
biomass), two allocation traits (root/shoot ratio and branch intensity,
branches biomass/main stem biomass) and two functional traits (specific
stem length and specific leaf area), which are potentially associated with
herbivore resistance and light capture, were measured. Overall, we found
that A. philoxeroides from introduced ranges had comparable biomass and
tolerance to specialist herbivores, lower branch intensity, lower specific
stem length and specific leaf area. Moreover, introduced populations
displayed higher shade tolerance of storage root biomass and lower plastic
response to shading in specific stem length. Finally, light availability
had no significant effect on evolution of tolerance to specialist
herbivores of A. philoxeroides. Our results suggest that post-introduction
evolution might have occurred in A. philoxeroides. While light
availability did not influence the evolution of tolerance to specialist
herbivores, increased shade tolerance and release from specialist insects
might have contributed to the successful invasion of A. philoxeroides.