Data from: Evolution of tolerance in an invasive weed after reassociation with its specialist herbivore

The interaction between the European wild parsnip Pastinaca sativa and its
coevolved florivore the parsnip webworm Depressaria pastinacella,
established in North America for over 150 years, has resulted in evolution
of local chemical phenotype matching. The recent invasion of New Zealand
by webworms, exposing parsnips there to florivore selection for the first
time, provided an opportunity to assess rates of adaptive response in a
real-time experiment. We planted reciprocal common gardens in the USA and
NZ with seeds from (1) US populations with a long history of webworm
association; (2) NZ populations that had never been infested and (3) NZ
populations infested for 3 years (since 2007) or 6 years (since 2004). We
measured impacts of florivory on realized fitness, reproductive effort and
pollination success and measured phenotypic changes in infested NZ
populations relative to uninfested NZ populations to determine whether
rapid adaptive evolution in response to florivory occurred. Irrespective
of country of origin or location, webworms significantly reduced plant
fitness. Webworms reduced pollination success in small plants but not in
larger plants. Although defence chemistry remained unchanged, plants in
infested populations were larger after 3–6 years of webworm florivory. As
plant size is a strong predictor of realized fitness, evolution of large
size as a component of florivore tolerance may occur more rapidly than
evolution of enhanced chemical defence.