Ecological Specialization of Two Photobiont- Specific Maritime Cyanolichen Species of the Genus Lichina

22 páginas, 4 tablas, 4 figurasAll fungi in the class Lichinomycetes are lichen-forming and exclusively associate with cyanobacteria. Two closely related maritime species of the genus Lichina (L. confinis and L. pygmaea) show similar distribution ranges in the Northeast Atlantic, commonly co-occurring at the same rocky shores but occupying different littoral zones. By means of 16S rRNA and phycocyanin operon markers we studied a) the phylogenetic relationships of cyanobionts associated with these species, b) the match of divergence times between both symbionts, and c) whether Lichina species differ in photobiont association and in how geography and ecology affect selectivity. The cyanobionts studied are closely related to both marine and freshwater strains of the genus Rivularia.We found evidence of a high specificity to particular cyanobiont lineages in both species: Lichina pygmaea and L. confinis incorporate specific lineages of Rivularia that do not overlap at the haplotype nor the OTU levels. Dating divergences of the fungal and cyanobacterial partners revealed an asynchronous origin of both lineages. Within each fungal species, selectivity varied across the studied area, influenced by environmental conditions (both atmospheric and marine), although patterns were highly correlated between both lichen taxa. Ecological speciation due to the differential association of photobionts to each littoral zone is suspected to have occurred in marine Lichina.Both ROA (BES-2013-066105) and SPO (CTM2012-38222-C02-02) were supported in the form of salary by grants from the Spanish Ministry of Economy and Competitiveness.Peer reviewe

Evolutionary success of prokaryotes

How can the evolutionary success of prokaryotes be explained ? How did they manage to survive conditions that have fluctuated, with drastic events over 3.5 billion years ? Which significant metabolisms and mechanisms have appeared over the course of evolution that have permitted them to survive the most inhospitable conditions from the physicochemical point of view ? In a 'Red Queen Race', prokaryotes have always run sufficiently fast to adapt to constraints imposed by the environment and the other living species with which they have established interactions. If the criterion retained to define the level of evolution of an organism is its capacity to survive and to yield the largest number of offsprings, prokaryotes must be considered highly evolved organisms