Surviving in isolation: genetic variation, bottlenecks and reproductive strategies in the Canarian endemic Limonium macrophyllum (Plumbaginaceae)

Oceanic archipelagos are typically rich in endemic taxa, because they offer ideal conditions for diversification and speciation in isolation. One of the most remarkable evolutionary radiations on the Canary Islands comprises the 16 species included in Limonium subsection Nobiles, all of which are subject to diverse threats, and legally protected. Since many of them are single-island endemics limited to one or a few populations, there exists a risk that a loss of genetic variation might limit their longterm survival. In this study, we used eight newly developed microsatellite markers to characterize the levels of genetic variation and inbreeding in L. macrophyllum, a species endemic to the North-east of Tenerife that belongs to Limonium subsection Nobiles. We detected generally low levels of genetic variation over all populations (HT = 0.363), and substantial differentiation among populations (FST = 0.188;RST = 0.186) coupled with a negligible degree of inbreeding (F = 0.042). Obligate outcrossing may have maintained L. macrophyllum relatively unaffected by inbreeding despite the species’ limited dispersal ability and the genetic bottlenecks likely caused by a prolonged history of grazing. Although several factors still constitute a risk for the conservation of L. macrophyllum, the lack of inbreeding and the recent positive demographic trends observed in the populations of this species are factors that favour its future persistence

The genus Sternbergia

Abstract Morpho-anatomical and karyologial studies were carried out on plants from S Italy of the three Italian species of the genus Sternbergia: S. colchiciflora, S. lutea and S. sicula. The morpho-anatomical features of the leaves are good taxonomic markers, especially concerning their colour, general shape, width and morphology of the median adaxial keel. Karyological analysis revealed the following chromosome complements: Sternbergia colchiciflora, 2n = 20; Sternbergia lutea, 2n = 22; Sternbergia sicula, 2n = 22. Karyotype variability is discussed in the light of previous literature. According to our results S. colchiciflora is confirmed to be the most isolated species, while S. lutea and S. sicula, easily recognizable on morphological grounds, appear instead very close karyologically