Paleobiogeography of Abies spp. and Cedrus atlantica in the Western Mediterranean (Iberian Peninsula and Morocco).

The Mediterranean species included in the genus Abies, and Cedrus atlantica show very limited distribution ranges at present. In this work, we outline the origin and migratory routes followed by Abies pinsapo, A. marocana, A. tazaotana and Cedrus atlantica, from the beginning of the Tertiary to the present, as well as the likely causes which have led their populations to their current state of isolation and danger of extinction. Abies and Cedrus would have reached the Western Mediterranean along with other elements of the arctotertiary flora between the Middle Eocene (45 Ma) and the Oligocene (30 Ma). They subsequently underwent speciation processes until relatively recent times, among which the opening of the Strait of Gibraltar (5.33 Ma) would have played an essential role. Mediterranean firs and cedars would have stayed in Southeastern Iberian and North African mountainous refugia during Quaternary glaciations-deglaciations. Despite a noticeable expansion and altitudinal migration in the Mid-Holocene thermal optimum, these species have experienced a further remarkable decline, as a result of the increasing aridity and pressure of human activities. The development of the most appropriate conservation strategies requires the best information on the response of these species to diverse disturbances, thus the knowledge on their temporal evolution becomes essential. The fossil record, both macrorests and pollen, contributes, along with diverse genetic studies, to assessing their resilience and vulnerability.