Out of the Mediterranean Region: Worldwide biogeography of snapdragons and relatives (tribe Antirrhineae, Plantaginaceae)

Abstract

Aim: The tribe Antirrhineae, including snapdragons, toadflaxes and relatives, is widely distributed across the Northern Hemisphere and the Neotropics. It displays an uneven distribution of diversity, with more than 50% of species and subspecies in the Mediterranean Region. Here we conducted the first detailed, worldwide biogeographic analysis of the Antirrhineae and tested two alternative hypotheses (time-forspeciation versus diversification rate differences) to explain the uneven distribution of diversity. Location: Worldwide, with a focus on the Mediterranean Region. Taxon: Tribe Antirrhineae (Plantaginaceae). Methods: A phylogenetic biogeographic approach was taken, accounting for area connections through time. Ancestral ranges, dispersal events, speciation and lineage accumulation within areas were estimated. Diversification rates for taxa present and absent in the Mediterranean Region were compared, accounting for the effect of a floral key innovation (nectar spur). Results: A proto-Mediterranean origin in the Late Eocene was estimated, and the Mediterranean Region stood out as the main centre for speciation and dispersal. Congruent patterns of long-distance dispersal from the Mediterranean Region to North America were recovered for at least two amphiatlantic clades. A significant floristic exchange between the Mediterranean and southwestern Asia was detected. We found no evidence of different diversification rates between lineages inside and outside the Mediterranean Region. Main conclusions: The Mediterranean Region played a key role in the origin of the current distribution of the Antirrhineae. However, the higher species richness found in this region appears to be the result of a time-for-speciation effect rather than that of increased diversification rates. The establishment of current Mediterranean climates in the Northern Hemisphere appears to have contributed to the recent diversification of the group, in combination with colonization of adjacent regions with arid and semi-arid climates.

Evolution in the Model Genus Antirrhinum Based on Phylogenomics of Topotypic Material

“…TreePL is suitable for divergence time estimation when dealing with large amounts of data, such as those yielded by GBS (Zheng and Wiens, 2015). Gorospe et al (2020). We first conducted an analysis under the "prime" option to select the optimal set of parameter values.…”

“…For biogeographic analyses we used the ultrametric tree resulting from TreePL after pruning the outgroup to avoid anomalous inferences of ancestral areas that may have resulted from the difference in sampling depth between outgroup and ingroup lineages. This approach also circumvents the potential effect of extinction between the outgroup and the ingroup expected after millions of years since the Oligocene (Gorospe et al, 2020). We additionally excluded four taxa originally described as different species but with limited phylogenetic and morphological distinctiveness that may have produced biogeographic bias: A. rothmalieri, A. dielsianum, A. caroli-paui, and A. boissieri.…”

Geo-Climatic Changes and Apomixis as Major Drivers of Diversification in the Mediterranean Sea Lavenders (Limonium Mill.)

“…Additionally, the Euro-Mediterranean area received a few Limonium species, mostly from the neighboring Irano-Turanian, North African, and Circumboreal regions, consistent with previous studies on other taxa (e.g., Mansion et al, 2008 , 2009 ; Salvo et al, 2010 ; Manafzadeh et al, 2014 ). The Euro-Mediterranean area also served as a major source of dispersals to other areas (see also tribe Antirrhineae: Gorospe et al, 2020 ), especially North Africa ( Figure 2 ). Accordingly, diversity in this latter region was shaped mostly by dispersals (ca.…”