Dwarf morphology of the annual plant Persicaria longiseta as a local adaptation to a grazed habitat, Nara Park, Japan

• Published in: Plant species biology 2008-12, Vol.23 (3), p.174-182
• Main Author: SUZUKI, RYO O
• Format: Article
• Language: English
• Subjects: deer grazing; dwarf phenotype; ecotype differentiation; local adaptation; phenotypic plasticity
• ISSN: 0913-557X; 1442-1984
• DOI: 10.1111/j.1442-1984.2008.00221.x

I conducted a common garden experiment using three populations of an annual species, Persicaria longiseta, with different grazing histories to compare plant morphology and its plasticity in response to grazing among populations. Seeds collected from the populations were assigned to clipping and nutrient treatments. Regardless of the treatment conditions, after 5 months individuals of the Nara Park population (long history of deer grazing) exhibited shorter shoots, smaller leaves and lower plant mass and developed a larger number of shoots and inflorescences compared with the Miwa and Heijo populations (no grazing history). Across nutrient conditions, the three populations exhibited few differences in plasticity in response to clipping. I also conducted a field experiment in which cultivated individuals from the three populations were transplanted to the Nara Park site. Results of the transplant experiment revealed that the dwarf morphology reduced grazing damage in such a way that small-formed individuals of the Nara population exhibited significantly higher survival and a lower grazing rate than large-formed individuals from the Miwa and Heijo populations. In conclusion, the dwarf morphology of P. longiseta in the Nara population is likely to have evolved as a genetically stable form as a result of selection pressure from deer grazing. Although phenotypic plasticity contributed in part to the development of the dwarf forms, I observed no evidence of evolution of plasticity specific to Nara Park.