Affiliations:
1Department of Biological Sciences and Biotechnology,
Chungbuk National University, Cheongju 28644, Republic of Korea
2School of Biological Sciences, Seoul National
University, Seoul 00826, Republic of Korea
3Department of Biological Sciences, Korea Advanced
Institute of Science and Technology, Daejeon 34141, Republic of Korea
4Forest Biodiversity Research Division, National
Arboretum, Pocheon 11186, Republic of Korea
*These authors contributed equally
Corresponding Author: Youngsung Joo (School of Biological Sciences,
Seoul National University, Seoul 00826, Republic of Korea, tel:
082-2-880-4423, email:
yousjoo@snu.ac.kr)
Abstract
- Many plants compensate for the damage caused by herbivorous insects
through tolerance responses. Besides directly causing plant tissue
loss and seed production reduction, herbivory causes phenological
changes in the host plant. However, little is known about the fitness
costs of phenological changes caused by tolerance responses to
herbivorous attacks.
- The girdling beetle Phytoecia rufiventris caused a short-term
decrease in the number of flowers of the host plant Erigeron
annuus . However, accelerated growth restored the number of flowers,
but after a 2-week delay. With an objective to examine whether the
tolerance response with such a delay fully compensates the fitness, we
experimentally reproduced a 2-week delay in germination under
greenhouse and field settings. Under both conditions, intraspecific
competition resulted in serious defects in the growth and reproduction
of E. annuus plants which of germination was delayed. However,
delayed germination resulted in better growth when competition and
herbivory were eliminated from the field.
- Thus, we showed that the tolerance response to restore reproductive
production does not fully compensate for the fitness loss caused by
insect attack; rather, the delay in seed production in attacked plants
leads to delayed germination and subsequent inferiority in
intraspecific competition.
- Synthesis. Our results imply that compensation for floral production
after an herbivore attack does not fully restore offspring fitness in
the presence of intraspecific competition and herbivory. Assessing the
ecological consequences of defense traits in an appropriate layer of
interaction is critical to interpreting adaptive values.
Keywords: Darwinian fitness, plant-herbivore interaction, tolerance
response, phenological shift, competition, Erigeron annuus ,