Microevolutionary processes on railway tracks in Geranium robertianum populations

A strongly modified habitat can be treated as “research field”, where microevolutionary processes in plants take place and can be traced. One of such areas are railway tracks. Difficult conditions for plant growth prevail there, including: insolation, water shortage and pollutions. This leads to natural selection, which favors microevolutionary processes. Geranium robertianum L. plants were tested, which occur on railway tracks (“track populations”) and in forests (“forest populations”), of north-eastern Poland. Totally, the phenotypic and genotypic diversity was checked in 20 track populations and 18 forest populations. The aim of the research was to check what was the taxonomic rank of a different biotype of G. robertianum, which is growing on the railway tracks in the village of Waliły-Station. The plants from this population in comparison to other studied populations were: smaller, had much smaller (about twice) and darker leaves with an increased level of anthocyanins (higher by a few – over a dozen % from plants from other track populations and about 50% from plants from forest populations). These features were preserved in the next generation (F1). However, molecular studies (AFLP) showed that the population from Waliły was not genetically distinct from other studied populations. The taxonomic rank of G. robertianum plants from the track population of Waliły-Station should be described as “form”. It is possible that this new form of G. robertianum plants could have arisen as a result of the occurrence of epigenetic processes, which could increase the phenotypic variability in G. robertianum and accelerate the adaptation of these plants to adverse conditions. The obtained results are an example of the initial stage of the process of microevolution in plants in anthropogenically transformed areas.