Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (5): 1166-1174.DOI: 10.3773/j.issn.1005-264x.2008.05.021

• Original article • Previous Articles     Next Articles

PATCHY CONTRAST OF HABITAT AFFECTS INTRACLONAL DIVISION OF LABOR OF POTENTILLA ANSERINA

LI Yuan-Heng1,2, WANG Zheng-Wen2,*(), MA Hui-Ling1   

  1. 1 Pratacultural College, Gansu Agricultural University, Lanzhou 730070, China, and
    2 State Key Laboratory of Vegetation and Environmental Changes, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2008-01-25 Accepted:2008-04-25 Published:2008-09-30
  • Contact: WANG Zheng-Wen

Abstract: Aims

When interconnected ramets of clonal plants grow under reciprocal patches in terms of the availabilities of different resources, they likely specialize morphologically and functionally to exploit locally abundant resource(s) more efficiently. This phenomenon is known as division of labor. Patchy contrast is a critical component that partially determines the occurrence and magnitude of division of labor. We investigate the effect of patchy contrast on intraclonal division of labor and test the hypothesis that the magnitude of division of labor is positively correlated with patchy contrast. We also examine the association between adaptive plasticity and division of labor.

Methods

We subjected connected ramet pairs of Potentilla anserina to reciprocal patchy environments with four levels of patchy contrasts, which were formed by providing ambient daylight but altering soil nutrient level for one ramet within each pair and providing a high soil nutrient level but changing light regime for the other. We measured shoot height, leaf area and shoot and root biomass. To quantify the magnitude of division of labor, we proposed an index based on root/shoot ratio (R/S) of ramets, namely, the ratio of difference between ramets in R/S to the sum of them.

Important findings

Shoot height and leaf area of P. anserina were highly plastic in response to local light availability, and such plasticity ultimately resulted in better ability to acquire scarce light resource, instead of abundant resource as predicted according to the rule of division of labor. This contradiction was probably due to the fact that the locally adaptive plasticity of shoot height and leaf area in response to local light environment took precedence over ramet specialization and division of labor, which was realized primarily by regulating biomass partitioning. The magnitude of division of labor peaked at the intermediate level of patch contrast and decreased both at the higher and lower levels. This pattern was likely an ultimate consequence of cost-benefit tradeoffs of ramet specialization. In conclusion, only when the benefits outweigh the costs at a certain patchy contrast, does division of labor occur, and there likely is an optimum patchy contrast that maximizes the division of labor. But under higher patchy contrast than the optimum one, division of labor may decrease as consequence of increased risks.

Key words: division of labor, habitat heterogeneity, patchy contrast, Potentilla anserina, root/shoot ratio (R/S)