par Nabet, Arié 
Promoteur Vereecken, Nicolas
Co-Promoteur Marshall, Leon
Publication Non publié, 2023-08-26
Promoteur Vereecken, Nicolas
Co-Promoteur Marshall, Leon
Publication Non publié, 2023-08-26
Mémoire
| Résumé : | Bees are essential pollinators of the majority of flowering plants. They are major players in the ecosystem service of pollination, which provides almost a third of the agricultural produce. However, wild bee (WB) communities are in decline in Europe and North America, mainly due to the destruction of their habitats. With 130 recorded species, the Canary Islands (CI) represent an insular hotspot for wild bee diversity because of their unique habitats and high rates of endemism. This thesis aims to explore the unique diversity of native bee fauna in the CI with four objectives. Firstly, the geographical origins of the species found on the different islands are studied in order to understand their historical patterns. We will analyze species checklists by island and categorize species as either endemic or shared with nearby regions. Secondly, I will utilize occurrence data from the Global Biodiversity Information Facility (GBIF) and the collection available at the ULB Agroecology Laboratory to examine the elevation and habitat preferences of the most common bee species in the Canary Islands and compare them across islands. This will provide insights into the niche requirements of native bees. Thirdly, factors from the equilibrium theory of island biogeography (ETIB) are applied to the diversity of endemic wild bee species native to the Canary Islands. Finally, the potential plant-pollinator networks and their characteristics in the natural areas of the Canary Islands are analysed, using a database of flowers visited by bees observed by Herbert Hohmann et al., in 1993.Our findings indicate Morocco as the likely origin for many of the bee species and the Canary Islands have a large pool of species compared with other Macaronesian islands. Insular delimitation is necessary to classify the species into three distinct groups, and the drivers of diversity vary among individual islands, including factors such as floral composition, land cover, and elevation. The theory of island biogeography explains the diversity patterns of wild bees, which differ for native and endemic species, one influenced by the age of the island and the other by its size. Furthermore, ETIB model demonstrates a good fit in explaining patterns of wild bee diversity and exhibits variations between native and endemic species. Quantification of pollination networks show island-specific statistics, highlighting a possible higher connectivity in endemic wild bee communitiesIn conclusion, diversity on oceanic island is driven by intensive speciation and migration process. Pollination network in the CI include super generalist endemic pollinators and oligolectic single island endemic (SIE) species, conservation efforts must consider the foraging habits of WB in their threatened natural habitats. |
