Continental‐scale diversification patterns in a megadiverse genus: the biogeography of Neotropical Begonia

Abstract

Aim The origin of Neotropical hyperdiversity is one of the most intriguing questions in modern biogeography and is best answered through the investigation of large, pantropically distributed genera, allowing the comparison of closely related clades in different regions. We produced a dated phylogeny and reconstructed ancestral ranges of the megadiverse, Andean‐centred genus Begonia to discern its dispersal history throughout the Neotropics and correlates of range evolution. Neotropical and Palaeotropical diversification rates were estimated. Location Neotropics: Central America, South America, West Indies and Mexico. Methods Plastid DNA sequence data from species representing the full geographical range and majority of sections of Neotropical Begonia were analysed with a secondarily calibrated relaxed molecular clock in order to estimate the age of crown groups and divergence times within Neotropical Begonia. Ancestral areas were reconstructed with a Bayesian approach to dispersal–vicariance analysis, a likelihood framework under a dispersal–extinction–cladogenesis model, and a Bayesian binary method. Diversification rates were estimated under a Bayesian framework. Results Biogeographical reconstruction indicated two independent trans‐Atlantic colonizations of the Neotropics from Africa. Early‐diverging lineages of both clades are reconstructed as having diversified in the mid‐Miocene, with multiple dispersal events between the Brazilian Atlantic rain forest and the Andes, and single radiations within the West Indies and Central America plus Mexico. Main conclusions Begonia displays numerous radiations within regions, punctuated by long‐distance dispersal. Successful colonization and diversification is predicted by the presence of upland habitat. Recognizing the role of chance dispersal events between available habitats is vital for understanding the formation of current biogeographical patterns.

Using dated molecular phylogenies to help reconstruct geological, climatic, and biological history: Examples from Colombia

“…An understanding of the age and patterns of diversification in these species would provide information on the development of the dry forest biome in Colombia and on when the geological/climatic conditions were appropriate for the development of a seasonally dry climate.4.3 | Cloud forestNeotropical cloud forests are restricted to altitudes of approximately 1,000 to 3,000 m. Lineages that are restricted to those altitudes would be expected to have begun to diversify from the crown node (the node in the phylogenetic tree at which point a lineage began to diversify) of the phylogeny at the age at which those altitudes were reached (Figure 1b) Moonlight et al (2015). Pennington and Dick (2010) indicated that populations of Cyathostegia mathewsii (Fabaceae) diversified in different Andean dry forests in Peru and Ecuador from c. 5.4 (+/−1.0) mya, with diversification within individual areas occurring from c. 2.8 (+/−0.6) mya.…”

Worldwide long‐distance dispersal favored by epizoochorous traits in the biogeographic history of Omphalodeae (Boraginaceae)

“…) was most likely from the Madrean region during early Miocene (ca. 17 mya) and via LDD since the closure of the Panama Isthmus was not fully completed until 8 mya (Coates et al, ; Bacon et al, ; Montes et al, ). The existence of island arcs between the two continents at around 15 mya (Krzywinski et al, ) could have facilitated this LDD.…”

Maintenance of species boundaries in a Neotropical radiation of Begonia

“…All three species are close relatives within section Gireoudia , one of three sections that together form a major clade of Central American Begonia (total 117 species, clade age 9.48 Ma [5.82–13.55 Ma, 95% highest posterior density, HPD], Moonlight et al . 2015). This clade is part of the large radiation of Neotropical Begonia (>600 species, clade age 12.46 Ma [7.87–17.24 Ma HPD] Moonlight et al .…”

“…This clade is part of the large radiation of Neotropical Begonia (>600 species, clade age 12.46 Ma [7.87–17.24 Ma HPD] Moonlight et al . 2015). …”