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The influence of intensive sheep grazing on genotypic differentiation in Danthonia linkii, D. richardsonii and D. racemosa on the New England Tablelands
Author(s) -
SCOTT A. W.,
WHALLEY R. D. B.
Publication year - 1984
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1984.tb01379.x
Subject(s) - tiller (botany) , biology , grazing , pasture , population , agronomy , genotype , botany , selection (genetic algorithm) , ecology , zoology , demography , sociology , biochemistry , artificial intelligence , gene , computer science
Genotypic differentiation studies involving three native pasture grasses Danthonia linkii Kunth, D. richardsonii Cashmore and D. racemosa R.Br. were made, using populations both collected from the field and grown from selfed seed, to investigate the influence of the intensive grazing and high soil fertility associated with sheep camps on a number of morphological and developmental characters. Each species was represented by at least a pair of populations one of which was sampled from a sheep campsite, the other(s) from an adjacent site as close as possible to the camp but outside its influence. The sheep camp populations were generally more prostrate with shorter tillers, greater tiller numbers, later flowering time, and in one population group, a larger number of seeds set. These differences were more apparent in the parent populations collected from the field but grown under uniform conditions than in the F 1 populations produced from selfed seed. These population differences were interpreted as representing genotypic differentiation produced by intensive selection pressures introduced since the development of the sheep camps. They were certainly more intensive in populations drawn from sheep camps which had been in existence for a longer time. The selection pressures which produced the new populations also appeared to maintain a broad base of genetic variability rather than result in populations more uniform than the original.