Timing and Tempo of Early and Successive Adaptive Radiations in Macaronesia

Abstract

The flora of Macaronesia, which encompasses five Atlantic archipelagos (Azores, Canaries, Madeira, Cape Verde, and Salvage), is exceptionally rich and diverse.Spectacular radiation of numerous endemic plant groups has made the Macaronesian islands an outstanding area for studies of evolution and speciation. Despite intensive investigation in the last 15 years, absolute age and rate of diversification are poorly known for the flora of Macaronesia. Here we report molecular divergence estimates and rates of diversification for five representative, putative rapid radiations of monophyletic endemic plant lineages across the core eudicot clade of flowering plants. Three discrete windows of colonization during the Miocene and early Pliocene are suggested for these lineages, all of which are inferred to have had a single colonization event followed by rapid radiation. Subsequent inter-archipelago dispersal events into Madeira and the Cape Verdes took place very recently during the late Pliocene and Pleistocene after initial diversification on the Canary Islands. The tempo of adaptive radiations differs among the groups, but is relatively rapid compared to continental and other island radiations. Our results demonstrate that opportunity for island colonization and successful radiation may have been constrained to discrete time periods of profound climatic and geological changes in northern African and the Mediterranean.

Adaptive radiation, correlated and contingent evolution, and net species diversification in Bromeliaceae

“…Diversification rates for the fastest diversifying bromeliad clades are comparable to those for the fastest adaptive radiations of plant lineages on islands, including the Hawaiian silversword alliance (0.56 My À1 [Baldwin and Sanderson, 1998]), Macaronesian Sideritis and Echium (0.79 and 0.60 My À1 [Kim et al, 2008]), and Hawaiian Cyanea (maximum of 1.36-2.09 My À1 [Givnish et al, 2009] Seehausen, 2006; see also McCune, 1997]). …”

Morphological and molecular data from Madeira support the persistence of an ancient lineage ofTaxus baccataL. in Macaronesia and call for immediate conservation actions

“…The colonization events of Macaronesian flora probably took place during some temporal frames: the upper Serravallian (14-11.8 Ma), the upper Tortonian (9.6-6.5 Ma) and the late Zanclean (5.2-4 Ma) (Kim et al 2008). Although European yew fossils dated back to the Middle Oligocene (32 Ma) (Mai 1995), major differentiation of T. baccata is supposed to have occurred in the upper Miocene (10-15 Ma) (Hageneder 2007).…”

“…Increasing efforts to draw biogeographical inferences in the Macaronesian archipelagos have been performed in the last 15 years, focusing on endemic plant species' evolution and speciation (Francisco-Ortega et al 1996;Juan et al 2000;Vargas 2007;Kim et al 2008), and providing valuable insights into the patterns of colonization, dispersal and taxonomic relationships among the region's endemics. The emerging pattern from recent phylogenetic studies envisions a scenario where recent and rapid radiations with a predominantly western Mediterranean origin coexist with lineage relicts of subtropical origin, forming part of the Macaronesian laurisilva of Tethyan-Tertiary flora (Bohle et al 1996;Francisco-Ortega et al 1996;Jorgensen and Frydenberg 1999;Helfgott et al 2000;Emerson 2002;Carine et al 2004;Vargas 2007).…”

Does Large Genome Size Limit Speciation in Endemic Island Floras?

“…Thus, to build a phylogeny of Canary endemics we used the program Phylomatic 2 [37] which utilizes current knowledge of phylogenetic relations between angiosperm taxa in combination with published phylogenies [38][39][40][41] and our own tree for available genera (Supplementary Material).…”