Level and distribution of genetic diversity in the European species Nardus stricta L. (Poaceae) inferred from chloroplast DNA and nuclear amplified fragment length polymorphism markers

摘要

The present level and distribution of genetic variation is defined by theinterplay between gene flow, drift, inbreeding, mutations and selection and reflectsboth contemporary and historical processes (e.g. Pleistocene glaciations). Especially,the breeding strategy of a species is a dominant factor influencing the pattern ofgenetic diversity. In this study, using AFLP molecular markers and cpDNAsequences, I investigate neutral genetic variation of nuclear and chloroplastgenomes of European populations of the grass Nardus stricta.The results of the present study indicate a lack of genetic variation inEuropean N. stricta populations; there were no cpDNA variation detected and onlythe Austrian population had different AFLP pattern from other populationsanalyzed. In earlier studies, it has been suggested that N. stricta reproduces viaagamospermy, and the observed lack of genetic variation strengthens thishypothesis about asexual reproduction in N. stricta. Also, given the lack of variationin both nuclear and chloroplast DNA it is likely that the present Europeanpopulations of N. stricta come from one refugium only, but it is impossible to saywhich based on our data. However, nucleotide variability is not the only source ofvariation that results in phenotypic variation. Epigenetic variation might enable thewide geographical distribution of N. stricta and explain the observed lack ofnucleotide variation. This might be interesting to investigate further.Even though AFLP is a high resolution technique, the resolving power of thetechniques used should be carefully investigated. I strongly emphasize that theseresults are preliminary as they are only based on screening of a few populations.More populations need to be screened and possibly also more primer/restrictionenzymes combinations before any conclusions can be drawn.