| Abstract: | In this paper, we elaborate on the method of contribution analysis in relation to body mass dynamics which has been proposed recently (Polishchuk, Vijverberg, 2005. Oecologia. V. 144. P. 268-277). We suggest that contribution analysis as applied to body mass dynamics makes a bridge between production-energetic approach and life history theory. Production is conventionally divided into somatic and reproductive components, and our approach shows how to estimate the role (i.e. contributions) of these components in body mass dynamics. The pattern of contributions is further interpreted in terms of life history. The approach is applied to study body mass dynamics of the cladoceran Daphnia galeata in response to improving trophic conditions. The performance of the method is found to depend on the resolution of food concentrations, that is, on how many food concentrations are examined and how far they are spaced on the food concentration axis. When resolution is fine, a shift in resource allocation priorities is detected - from somatic component attracting more resources under harsh food conditions to reproduction attracting more resources under favorable conditions. However, when resolution is poor this pattern remains hidden. In that case, we observe roughly equal contributions of somatic and reproductive components to body mass dynamics. |
