Aim: Understanding how grain size affects our ability to characterize species responses to ongoing climate change is of crucial importance in the context of an increasing awareness for the substantial difference that exists between coarse spatial resolution macroclimatic data sets and the microclimate actually experienced by organisms. Climate change impacts on biodiversity are expected to peak in mountain areas, wherein the differences between macro and microclimates are precisely the largest. Based on a newly generated fine‐scale environmental data for the Canary Islands, we assessed whether data at 100 m resolution is able to provide more accurate predictions than available data at 1 km resolution. We also analysed how future climate suitability predictions of island endemic bryophytes differ depending on the grain size of grids.Location: Canary Islands.Time period: Present (1979–2013) and late‐century (2071–2100).Taxa: Bryophytes.Methods: We compared the accuracy and spatial predictions using ensemble of small models for 14 Macaronesian endemic bryophyte species. We used two climate data sets: CHELSA v1.2 (~1 km) and CanaryClim v1.0 (100 m), a downscaled version of the latter utilizing data from local weather stations. CanaryClim also encompasses future climate data from five individual model intercomparison projects for three warming shared socio‐economic pathways.Results: Species distribution models generated from CHELSA and CanaryClim exhibited a similar accuracy, but CanaryClim predicted buffered warming trends in mid‐elevation ridges. CanaryClim consistently returned higher proportions of newly suitable pixels (8%–28%) than CHELSA models (0%–3%). Consequently, the proportion of species predicted to occupy pixels of uncertain suitability was higher with CHELSA (3–8 species) than with CanaryClim (0–2 species).Main conclusions: The resolution of climate data impacted the predictions rather than the performance of species distribution models. Our results highlight the crucial role that fine‐resolution climate data sets can play in predicting the potential distribution of both microrefugia and new suitable range under warming climate.

Since its coinage ca. 1850 AD by Philip Barker Webb, the biogeographical region of Macaronesia, consisting of the North Atlantic volcanic archipelagos of the Azores, Madeira with the tiny Selvagens, the Canaries and Cabo Verde, and for some authors different continental coastal strips, has been under dispute. Herein, after a brief introduction on the terminology and purpose of regionalism, we recover the origins of the Macaronesia name, concept and geographical adscription, as well as its biogeographical implications and how different authors have positioned themselves, using distinct terrestrial or marine floristic and/or faunistic taxa distributions and relationships for accepting or rejecting the existence of this biogeographical region. Four main issues related to Macaronesia are thoroughly discussed: (i) its independence from the Mediterranean phytogeographical region; (ii) discrepancies according to different taxa analysed; (iii) its geographical limits and the role of the continental enclave(s), and, (iv) the validity of the phytogeographical region level. We conclude that Macaronesia has its own identity and a sound phytogeographical foundation, and that this is mainly based on three different floristic components that are shared by the Macaronesian core (Madeira and the Canaries) and the outermost archipelagos (Azores and Cabo Verde). These floristic components are: (i) the Palaeotropical‐Tethyan Geoflora, formerly much more widely distributed in Europe and North Africa and currently restricted to the three northern archipelagos (the Azores, Madeira and the Canaries); (ii) the African Rand Flora, still extant in the coastal margins of Africa and Arabia, and present in the southern archipelagos (Madeira, the Canaries and Cabo Verde), and (iii) the Macaronesian neoendemic floristic component, represented in all the archipelagos, a result of allopatric diversification promoted by isolation of Mediterranean ancestors that manage to colonize Central Macaronesia and, from there, the outer archipelagos. Finally, a differentiating floristic component recently colonized the different archipelagos from the nearest continental coast, providing them with different biogeographic flavours.

Myrica rivas-martinezii is a critically endangered endemic of the laurel forest of the Canary Islands and co-occurs very close to M. faya. Some authors suggest that M. rivas-martinezii and M. faya are two morphs of the same species, so molecular markers were used to estimate the levels and structuring of genetic variation within and among natural populations in order to evaluate genetic relationships between these two congeners. Six polymorphic microsatellite (simple sequence repeat, SSR) markers were used to determine the genetic diversity and the genetic relationship between both Myrica species. Most of the natural populations analysed were in Hardy–Weinberg equilibrium for both taxa. Analysis of molecular variance (AMOVA) for both species revealed that most of the genetic variability detected was contained within populations (92·48 and 85·91 % for M. faya and M. rivas-martinezii, respectively), which it is consistent with outcrossing and dioecious plants. Estimates of interpopulation genetic variation, calculated from F_ST and G′_ST, were quite low in the two taxa, and these values did not increase substantially when M. rivas-martinezii and M. faya populations were compared. The UPGMA dendrogram based on Nei's genetic distance clustered the populations by their island origin, independently of taxon. In fact, the mixture of individuals of both taxa did not appreciably disrupt the intrapopulational genetic cohesion, and only 3·76 % variation existed between species. 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.