Potential distribution of Poa compressa L. adventive species in Siberia

Species migration is a natural process but in recent years the mobility of species has significantly increased and a special group of so-called invasive species is recognized by biologists. In contrast to alien species introduced intentionally or unintentionally outside their natural habitats, invasive species actively invade natural communities and occupy new ecological niches. This leads to significant changes in plant communities. Invasive species also affect the evolutionary process. Because of introgressive hybridization, for example, they can alter the gene pool of native species and even cause a total extinction of close species. It is known that the success of introduction and distribution of species on a new territory is only possible in the terms of similarity of environmental conditions. Therefore, knowing the ecological niche of species, it is possible to predict the areas of its successful introduction. The modern scientific approach to the study of invasive species is revealing its potential ability for distribution and potential range. Bioclimatic modeling, based on the GIS technology, can identify the areas, suitable for its climate conditions for species growth. Poa compressa L. is a widespread species which occurs not only in the northern hemisphere, but even in Australia. In the U.S. and Canada this species is included on the list of invasive and harmful plants. Being a common species in Europe, it has almost not been found in Siberia, but lately it has been encountered here quite often. This species has been found in Tomsk and Kemerovo Oblasts, occurring mainly in disturbed habitats along the roadsides, on embankments and mine dumps. This species seems to hybridize successfully with local relative species P. palustris L. and P. nemoralis L. and might be a potentially harmful species in Siberia, altering the genotype of native ones. In order to reveal the potential possibility of P. compressa for distribution in Siberia, we obtained its ecological niche, based on 19 bioclimatic characteristics (19 variables with a spatial resolution of 2.5 arc-min), using the program DIVA GIS 5.2. The analysis of histograms, which show the frequencies of climate variables Bio1Bio19, appropriated to P. compressa range, has revealed the variability of these characteristics within that area. This analysis showed that only the characteristics, describing the temperature parameters were the closest to the normal distribution. Conversely, the graphs which concern precipitations, quite often were not simply asymmetrical, but their left part looked as if it had been cut in their “driest” part. Obviously, in the areas with arid conditions P. compressa distribution seems to be limited by some other, more potent factor. We also constructed predictive distribution maps, using the BIOCLIM and DOMAIN methods. These maps identified the areas where the probability of occurring of P. compressa was the highest. In Siberia such areas have proved to occupy vast areas, especially on the maps created using the algorithm DOMAIN, which is considered to be more accurate than BIOCLIM. The obtained data of the potential range of P. compressa suggest both a wider distribution of this species and a relatively high potential of its settlement in Siberia. Its inclination to hybridization with related species P. palustris and P. nemoralis can relate in significant changes in the gene pool of these three species. Probably, Siberian botanists should be more attentive to this species and to control its spread. Acknowledgments: This work was carried out with the support of Grant RFBR 13-04-017-15А. The authors thank the curators of the herbariums BYU, LE, TK, US, UTC, Nevada for the opportunity to work with collections; Thomas Albright, professor of the University of Nevada (Reno, USA) for consultations on geostatistical modeling and valuable advice. The article contains 3 figures, 34 ref.

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