One Species, One Genotype: No Genotypic Variability in the Extremely Narrow Endemic Tetraploid Agrostis Barceloi (Gramineae)

We used allozyme electrophoresis to survey genetic diversity of Agrostis barceloi L.Sáez & Rosselló, an extremely narrow endemic species from the island of Majorca (Balearic Islands, Western Mediterranean Basin). This species is a tetraploid with a single natural population of less than 100 individuals. All analyzed individuals of A. barceloi showed the same genotype. Four out of 18 interpretable loci showed fixed heterozygosity (thus supporting an allopolyploid origin). The genotypic uniformity of this species may be attributed to a founder effect associated with a dispersal event of its ancestor from the continent, a very small current effective population size (N e), and a series of natural or anthropogenic threats affecting the population. We propose several conservation measures such as seed storing and plant production for further reinforcements (which do not need any previous work for selecting individuals because of the genetic uniformity). In addition, we suggest the preservation of the mountain summit where the species is found (Puig Major), which would also positively influence the conservation of other co-occurring ENEs and other rare and threatened species.