Adaptation on the ground and beneath: does the local population maximize its lambda(1)?

作者：Logofet Dmitrii O^*; Ulanova Nina G; Belova Iya N

来源：Ecological Complexity, 2014, 20: 176-184.

DOI：10.1016/j.ecocom.2014.10.001

• Perennial grass
• Age-stage structure
• Life cycle graph
• Polyvariant ontogeny
• Projection matrix
• Reproductive submatrix
• Dominant eigenvalue
• Direct calibration

Local populations of plant species, such as perennial grasses, are considered to adapt to their environments by means of polyvariant ontogeny, i.e., diverse pathways that an individual plant may follow through a variety of states in its life cycle expressed as the ontogenetic stages and chronological ages (in years). The corresponding projection matrix (L) in a matrix population model turns out to have a more complex pattern than the classical Leslie or Lefkovitch ones. The dominant eigenvalue (Xi) of L, in spite of the asymptotic role it plays in model dynamics, does measure the adaptation that the local population possessed in the place where, and at the time when, the population data were collected to calibrate the matrix L. The value of X, thus serves as the basis for site- and time-specific comparative studies, where the problem reduces to reliable matrix calibration on the specific data. The kind of data we deal with in a case study of vegetatively propagating woodreed (Calamagrostis epigeios) is called 'identified individuals with unknown parents' (Logofet, 2008, 2013c): we determined reliably the age-stage-specific status of each individual plant from the morphology of its above-ground part, but the parent-progeny rhizome links remained reliably hidden in the ground. Therefore, this kind of data enabled direct calculation of the transition part T in matrix L=T+F, but leaved the fertility part F uncertain, yet subject to certain linear constraints. The uncertainty gets eliminated if the maximal possible Xi is hypothesized. Given the data and constraints, the calibration then reduces to a nonlinear constraint maximization problem, which has a unique solution. In order to test the maximization hypothesis, we have now designed a field experiment where a few sample plots with C epigeios are dug out to disentangle the parent-progeny relations, hence to calculate the state-specific fertility rates (matrix F) in the direct way. We report on the outcome of the first-year experiment, which has confirmed the maximization hypothesis and revealed unexpected complexity in the popular methodology of Xi as a measuring tool of comparative demography.

• 出版日期2014-12