Population genetic variability of Poa annua cpDNA, an invasive plant in Antarctica

Antarctica is one of the most isolated regions on Earth. Significant distance from other continents and extreme environmental conditions create very strong geographical and survival barriers to biological invasions. Despite these barriers, many alien plant propagules are transported there every year and one invasive species, Poa annua established a stable population there. Previous research suggests that the source population of invasion originates from Powsin in Poland. We examined genetic variability of selected non-coding cpDNA fragments in eight populations from different parts of the world, including Powsin, Antarctica and common ports used for Antarctic transport, to track the source of this invasion and species genetic variability. For 127 individuals we detected 53 cpDNA haplotypes. Analysis of these fragments indicated low degree of population differentiation. We detected one haplotype prevailing in all populations and numerous private haplotypes in each population, including the Antarctic one. The lack of specific grouping of the Antarctic population with other populations, disabled the indication of one specific source population. Additionally, we did not observe a lower intrapopulation variability of the Antarctic population in comparison to populations from the species primary range. Our results suggest multiple introductions playing significant role in invasion process in Antarctica, protecting the population against a decline in variability as a result of the founder effect or bottleneck and also supporting the known phenomena of Genetic Paradox of Invasions. Because of that and high species phenotypic plasticity, protection of Antarctica and its unique environment should focus on preventing transfer of any foreign propagules.