Search

Premise of research. Biogeography has improved understanding of evolution and diversification of organisms on both continental and island systems. One complicated island group in terms of geological history and biogeographic pattern is the Caribbean island system. A comparison across taxonomic groups does not result in overarching patterns for this group of islands. Columnea has the greatest number of species endemic to the Caribbean for any genus in Gesneriaceae that is not mostly endemic to the Caribbean with 16 species. Thirteen of these species are found on Jamaica, the remaining three each endemic to Cuba, Hispaniola, and Puerto Rico. In addition, populations of Columnea sanguinea and Columnea scandens are known from both mainland and multiple Caribbean islands. We investigate the pattern of evolution in Caribbean species of Columnea and attempt to explain the large number of species found on the island of Jamaica relative to the other islands. We explicitly test whether Caribbean species of Columnea are monophyletic and whether the 13 species endemic to Jamaica are a monophyletic group. This genus can help understand biogeographic patterns and modes of speciation in the Caribbean. Methodology. We sampled all Caribbean species of Columnea using DNA sequence data and phylogenetic methods to understand the pattern of diversity to determine whether multiple or single introductions could explain the diversity on the Caribbean islands. Pivotal results. The Caribbean species do not form a monophyletic group. The Jamaican species are monophyletic, and the endemic Cuban species, Columnea tincta , is sister to 12 of the Jamaican species, with Columnea pubescens sister to C. tincta + remaining Jamaican species. Most Jamaican species share similar corolla morphologies to section Columnea. Although never recovered as part of section Columnea , approximately unbiased tests cannot reject a sister group relationship of the Jamaican/Cuban endemic clade to section Columnea but can reject inclusion in section Columnea. Conclusions. The high diversity of Columnea in the Caribbean is due to the disproportionate number of species on Jamaica, but there is no obvious explanation for the radiation on this island, despite considering island size, topography, pollinators, and dispersers. The large number of species could be attributed to over-splitting on Jamaica, but even if a narrower concept were followed, and four of the species were combined as varieties of Columnea hirsuta as earlier taxonomy had predicted, the number of morphologically distinctive species would still be nine and much greater than that of the other islands. Our data also indicate that C. hirsuta sensu lato is not monophyletic. [ABSTRACT FROM AUTHOR]

[Display omitted] • The eco-evolutionary history of insular Caribbean Sticta was explored. • Species assemblages date back to the early Miocene and show strong biogeographic links to South America. • Colonization of the islands did not increase diversification rates. • Environmental variation most strongly explains taxonomic and phylogenetic turnover between island-level communities. Phylogenetic approaches to macroevolution have provided unique insight into evolutionary relationships, ancestral ranges, and diversification patterns for many taxa. Similar frameworks have also been developed to assess how environmental and/or spatial variables shape species diversity and distribution patterns at different spatial/temporal scales, but studies implementing these are still scarce for many groups, including lichens. Here, we combine phylogeny-based ancestral range reconstruction and diversification analysis with community phylogenetics to reconstruct evolutionary origins and assess patterns of taxonomic and phylogenetic relatedness between island communities of the lichenized fungal genus Sticta in the Caribbean. Sampling was carried out in the Greater Antilles (Cuba, Jamaica, Dominican Republic, and Puerto Rico) and Lesser Antilles (Dominica, Guadeloupe, and Martinique). Data for six molecular loci were obtained for 64 candidate Caribbean species and used to perform both macroevolutionary phylogenetics, which also included worldwide taxa, and phylobetadiversity analyses, which emphasized island-level communities. Our work uncovered high levels of island endemism (∼59%) in Caribbean Sticta. We estimate initial colonization of the region occurred about 19 Mya from a South American ancestor. Reverse migration events by Caribbean lineages to South America were also inferred. We found no evidence for increased diversification rates associated with range expansion into the Caribbean. Taxonomic and phylogenetic turnover between island-level communities was most strongly correlated with environmental variation rather than with geographic distance. We observed less dissimilarity among communities from the Dominican Republic and Jamaica than between these islands and the Lesser Antilles/Puerto Rico. High levels of hidden diversity and endemism in Caribbean Sticta reaffirm that islands are crucial for the maintenance of global biodiversity of lichenized fungi. Altogether, our findings suggest that strong evolutionary links exist between Caribbean and South American biotas but at regional scales, species assemblages exhibit complex taxonomic and phylogenetic relationships that are determined by local environments and shared evolutionary histories. [ABSTRACT FROM AUTHOR]

Myrteae (c. 2500 species; 51 genera) is the largest tribe of Myrtaceae and an ecologically important groups of angiosperms in the Neotropics. Systematic relationships in Myrteae are complex, hindering conservation initiatives and jeopardizing evolutionary modelling. A well-supported and robust phylogenetic hypothesis was here targeted towards a comprehensive understanding of the relationships within the tribe. The resultant topology was used as a base for key evolutionary analyses such as age estimation, historical biogeography and diversification rate patterns. One nuclear ( ITS ) and seven chloroplast ( psbA-trnH , matK , ndhF , trnl - trnF , trnQ - rps16 , rpl16 and rpl32 - trnL ) DNA regions for 115 taxa representing 46 out of the 51 genera in the tribe were accessed and analysed using maximum likelihood and Bayesian inference tools for phylogenetic reconstruction. Dates of diversification events were estimated and contrasted using two distinct fossil sets (macro and pollen) in BEAST. The subsequent dated phylogenies were compared and analysed for biogeographical patterns using BioGeoBEARS and diversification rates using BAMM. Myrteae phylogeny presents strong statistical support for three major clades within the tribe: Australasian group, Myrtus group and Main Neotropical Lineage. Dating results from calibration using macrofossil are an average of 20 million years older and show an early Paleocene origin of Myrteae, against a mid-Eocene one from the pollen fossil calibration. Biogeographic analysis shows the origin of Myrteae in Zealandia in both calibration approaches, followed by a widespread distribution throughout the still-linked Gondwana continents and diversification of Neotropical endemic lineages by later vicariance. Best configuration shift indicates three points of acceleration in diversification rates, all of them occurring in the Main Neotropical Lineage. Based on the reconstructed topology, several new taxonomic placements were recovered, including: the relative position of Myrtus communis , the placement of the Blepharocalyx group, the absence of generic endemism in the Caribbean, and the paraphyletism of the former Pimenta group. Distinct calibration approaches affect biogeography interpretation, increasing the number of necessary long distance dispersal events in the topology with older nodes. It is hypothesised that biological intrinsic factors such as modifications of embryo type and polyploidy might have played a role in accelerating shifts of diversification rates in Neotropical lineages. Future perspectives include formal subtribal classification, standardization of fossil calibration approaches and better links between diversification shifts and trait evolution. [ABSTRACT FROM AUTHOR]