Evolução e endemismo em um grupo de insetos aquáticos morfologicamente crípticas (Ephemeroptera, Baetidae) nas ilhas do nordeste da Macaronésia

Oceanic islands are natural laboratories of evolution and their colonization histories provide insights into how dispersal and speciation shape present-day biodiversity. Species in some taxonomic groups are thought to be cryptic. When islands contain cryptic taxa, a clear understanding of taxonomic affinities between islands and the mainland, which may have acted as a source of colonists in the past, is a necessary first step in phylogenetic reconstruction.

This project is reconstructing the phylogenetic relationships of small minnow mayflies (Ephemeroptera, Baetidae) from three Macaronesian island groups (Azores, Madeira, Canaries), as well as from Corsica, mainland Europe, and North Africa.  Eight species were previously recorded from Macaronesia, six of them belonging to the Baetis (Rhodobaetis) or Cloeon dipterum s.l. species groups. Both groups are thought to contain undescribed and morphologically cryptic species. DNA-barcode fragment of the mitochondrial cox1 gene and the general mixed Yule-coalescent (gmyc) model have been used to delineate putative species.

The model has delineated twelve putative species in Macaronesia. Phylogenetic reconstruction using Bayesian inference has shown that Madeira shared one species with the European mainland (Baetis atlanticus) and all others were endemic to single islands.

A second species on Madeira (Baetis enigmaticus) is closely related to a species group from the Canary Islands (B. pseudorhodani s.l.). Lineages (B. canariensis s.l. and B. pseudorhodani s.l.) appear to have diversified in parallel throughout the Canary Islands. The closest relative of B. canariensis s.l. on Gran Canaria was found in Tunisia, indicating a complex colonization history and close links with North Africa.

The extremely restricted distribution of some endemic species (currently known from only one or two locations at most) means they may well be the most endangered freshwater insects in Europe.