Journal
PLANT ECOLOGY
Volume 147, Issue 2, Pages 227-235Publisher
SPRINGER
DOI: 10.1023/A:1009856732262
Keywords
Argentine; ecotypic differentiation; genetic variation; grasses; isozymes; phenotypic plasticity
Categories
Ask authors/readers for more resources
Native populations of perennial grasses subjected to heavy grazing are typically shorter and more prostrate than ungrazed or lightly defoliated ones. However, it is often difficult to find out whether the morphological modifications are the result of genetic differentiation or phenotypic plasticity. Piptochaetium napostaense (Speg.) Hack. is a native perennial cool-season palatable grass with a dwarf form abundant in the areas subjected to heavy grazing. In this study, we tried to determine whether the populations with different grazing histories are genetically differentiated. We considered three different grazing conditions: enclosure (prevented from grazing during 20 years), livestock grazing, and burrow (heavily grazed by cattle and a wild rodent herbivore, the vizcacha). Isozyme analyses were carried out in order to assess the genetic variability of the populations under study. We further studied the progeny of plants with different grazing histories to determine whether the morphological differences are transmitted to the next generation. Seedlings obtained from seeds belonging to enclosure and burrow were grown in the greenhouse and their vegetative and reproductive response under different water and nutrient availability levels were recorded. From the isozymes analyses we found low levels of genetic variation in the populations studied, with an average of 20.5% polymorphic loci, 1.2 alleles per locus and 0.015 mean expected heterozygosity. From the total genetic diversity, only 1.4% was due to differences among population. In addition, either enclosure or burrow populations had the same growth and reproductive response over treatments differing in water and nutrient levels. The morphological differentiation among plants with different grazing histories appears to be the outcome of a phenotypically plastic response of adapted genotypes.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available