Biodiversity in Numbers
Fauna and floristic diversity is very rich in the archipelagos of Macaronesia, but is smaller in the archipelagos geographically farther from the continents (Azores case), which is certainly related to distance, geological age and various historical events (eg, volcanism , human intervention) verified in each of the different islands.
In 2010, the total number of terrestrial species and subspecies (= taxa) in the Azores was estimated at 6164, of which 452 are endemic, corresponding to 7.3% of the total diversity. Note that these numbers are lower than those of the Madeira archipelago, estimated at 7571 land taxa, including 1419 endemic (19% of total diversity). However, it is believed that these values are underestimated, given that there are terrestrial and marine species (known and still unknown to science) that could increase this number to about 10,000 species and subspecies.
However, arthropods (Filo Arthropoda, which includes crustaceans, centipedes and millipedes, mites, spiders and insects, among other animals) have the highest diversity (2332 taxa), representing about 42% of the species found in the Azores. Considering all fungi (including lichens) and seedlings (spermatophytes), they represent the second (24%) and third (18%) more diverse groups of organisms in these islands.
In the case of insects, the Azores have less specific wealth (1773 taxa) than Madeira and Selvagens (3297 taxa). In particular, the Odonata are represented by four confirmed species for the Azorean archipelago (two more sporadic) and six species for Madeira and Selvagens, none of which are specifically endemic to these archipelagos. However, Sympetrum nigrifemur is considered an endemism of Macaronesia, being present in Madeira and the Canary Islands. On the other hand, in the Azores lies a “biological jewel”, the damselfly Ischnura hastata, the only species of odonates in the World with parthenogenetic reproduction (exclusively female reproduction, in the absence of males.
The animals and the terrestrial plants are the groups with greater diversity in endemismos. Indeed, in the Azores there are at least 266 arthropods and about 80 endemic vascular plants (Pteridophyta and Spermatophyta).
As for arthropods, most of them are exotic (58%). On the other hand, more than 60% of the vascular flora of the Azores is considered as exotic, while mammals (except the two native bats), amphibians and reptiles were introduced.