Ecotypic variation in relation to man made habitats in Capsella: Field and trampling area

Abstract

Intraspecific differentiation of the worldwide distributed weed Capsella bursa-pastoris has been studied on a local scale. Differentiation patterns are clearly correlated to man made habitats (arable field as opposed to trampling area). a) The seeds of the arable field population seemed to increase germination when covered with soil in contrast to the trampling area population. b) Arable field - early flowering with low variability; greater plant height and more stem branches; larger seed pots; higher seed output. c) Trampling area - late flowering, well developed rosettes;high phenotypic plasticity in begin of flowering, plant height, branching number and fruit dimensions. d) Nutrient supply increased rosette diameter, plant height, number of stem branches, fruit dimensions and seed number within the arable field population, bur not the trampling area plants; instead, numbers of rosette leaves and branching number. The reaction norm between the populations was different for some fitness parameters: nutrient supply decreased phenotypic variability in rosette diameter within the arable field population whereas in the trampling area population it decreased phenotypic variability in plant height, branching number and fruit dimensions. Both populations differed significantly in all measured parameters. The relation of characters to habitat is discussed.