No abstract

All the results obtained using molecular markers indicate clearly that both taxa share the same genetic pool, and they are probably the same taxa. Considering that M. rivas-martinezii is classified as at risk of extinction, there should be a change of focus of the current management actions for the conservation of this putatively endangered Canarian endemic.

The main objective of this study was to analyze if Acacia farnesiana, an introduced shrub from North and Central American tropics is spreading from areas in which it was introduced, and also to determine which animals operate as vectors for the shrub dispersion in the study area. The study site was located in southern Gran Canaria, one of the islands of the Canary Island archipelago. We selected six ravines in an area where approximately 40 plants of A. farnesiana were planted around 40 years ago. We analyzed the size structure of the population of A. farnesiana (density and biovolume) in the ravines, as well as its spatial distribution, in order to assess the degree of aggressiveness of this shrub in terms of spreading and expansion. Our results suggest that this shrub is spreading to new areas very quickly due to dispersion of seed by rabbits and an enhanced germination by the action of Mimoseste mimosae, a bruchid that decreases the germination period of the seed once it has separated from the fruit. Based on the results obtained in this study, we strongly suggest that managers of this area consider a management program to control further spread.

No abstract

Oceanic islands are dynamic settings that often promote within-island patterns of strong population differentiation. Species with high colonisation abilities, however, are less likely to be affected by genetic barriers, but island size may impact on species genetic structure regardless of dispersal ability. The aim of the present study was to identify the patterns and factors responsible for the structure of genetic diversity at the island scale in Phoenix canariensis, a palm species with high dispersal potential. To this end, we conducted extensive population sampling on the three Canary Islands where the species is more abundant and assessed patterns of genetic variation at eight microsatellite loci, considering different within-island scales. Our analyses revealed significant genetic structure on each of the three islands analysed, but the patterns and level of structure differed greatly among islands. Thus, genetic differentiation fitted an isolation-by-distance pattern on islands with high population densities (La Gomera and Gran Canaria), but such a pattern was not found on Tenerife due to strong isolation between colonised areas. In addition, we found a positive correlation between population geographic isolation and fine-scale genetic structure. This study highlights that island size is not necessarily a factor causing strong population differentiation on large islands, whereas high colonisation ability does not always promote genetic connectivity among neighbouring populations. The spatial distribution of populations (i.e. landscape occupancy) can thus be a more important driver of plant genetic structure than other island, or species' life-history attributes.