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Aim: Our aim was to investigate the historical biogeography of the three genera of the Leucocroton alliance (i.e. Garciadelia Jestrow & Jiménez Rodr., Lasiocroton Griseb., and Leucocroton Griseb., Euphorbiaceae). Location: The alliance is restricted to the Bahamas, Cuba, Hispaniola and Jamaica. Methods: Members of the Leucocroton alliance, along with representatives from tribe Adelieae (Adelia L. and Philyra Klotzsch.), were included in a molecular phylogenetic analysis based upon nucleotide sequences of the internal transcribed spacer region of the nuclear ribosomal DNA and the non-coding chloroplast regions psbM-trnD and ycf6-pcbM. The program s-DIVA was used to calculate ancestral areas based on the phylogenetic trees and present species distributions. Results: Phylogenetic analyses support the monophyly of the three genera. The ancestral area of the Leucocroton alliance is eastern Cuba and Hispaniola. Ancestral forms of Leucocroton arose on eastern Cuba and underwent two migrations across the island. The ancestor of Lasiocroton also originated on eastern Cuba followed by later dispersal to and speciation events on the other islands. Our study also suggests that ancestral forms of the Leucocroton alliance probably occurred on limestone soils. Main conclusions: Our study concurs with previous hypotheses suggesting that the flora of serpentinite regions of the Caribbean derives from other types of soils. The serpentine endemics of the Leucocroton alliance have a single origin and represent one of the most extraordinary examples of speciation in this unique environment of the New World. The high colonization success achieved by the members of Leucocroton on serpentine soils was not attained by the other genera of the alliance, which occur on limestone areas.

Isoprene emissions are a key component in biosphere–atmosphere interactions, and the most significant global source is the Amazon rainforest. However, intra- and interannual variations in biological and environmental factors that regulate isoprene emission from Amazonia are not well understood and, thereby, are poorly represented in models. Here, with datasets covering several years of measurements at the Amazon Tall Tower Observatory (ATTO) in central Amazonia, Brazil, we (1) quantified canopy profiles of isoprene mixing ratios across seasons of normal and anomalous years and related them to the main drivers of isoprene emission – solar radiation, temperature, and leaf phenology; (2) evaluated the effect of leaf age on the magnitude of the isoprene emission factor (Es) from different tree species and scaled up to canopy with intra- and interannual leaf age distribution derived by a phenocam; and (3) adapted the leaf age algorithm from the Model of Emissions of Gases and Aerosols from Nature (MEGAN) with observed changes in Es across leaf ages. Our results showed that the variability in isoprene mixing ratios was higher between seasons (max during the dry-to-wet transition seasons) than between years, with values from the extreme 2015 El Niño year not significantly higher than in normal years. In addition, model runs considering in situ observations of canopy Es and the modification on the leaf age algorithm with leaf-level observations of Es presented considerable improvements in the simulated isoprene flux. This shows that MEGAN estimates of isoprene emission can be improved when biological processes are mechanistically incorporated into the model.

The Bahamian archipelago consists of approximately 2,400 islands occurring in the Atlantic Ocean off the coasts of Florida, Cuba, and Hispaniola. In 1982 Donovan Correll and Helen Correll published the most current synopsis of the floristic diversity of this island chain. Their publication cited a total of 1,371 vascular plant species of which 114 seed plants were listed as endemic to the archipelago (∼8 % of the native flora). In the last 30 years, additional herbarium collections and taxonomic studies have shown that a number of species previously indicated to be endemic to these islands also occur in other regions or have been taxonomically merged into other species. The current number of species considered endemic to the Bahamian archipelago is 89 (∼6 % of the total flora). There are 50 endemic species that have a known distribution on one (31 species) or two island groupings (19 species). Biogeographical analyses of endemic plant distributions shows three distinct clusters of species: southern, central, and the northern islands, with a fourth cluster that includes islands with a small area and one medium size island that seems that has been underexplored (i.e., Little Inagua). We anticipate that understanding the conservation status of endemic species and their distributions will help to develop legislation to preserve this Bahamian natural heritage.

Myrtaceae are a large family of trees and shrubs, including ca. 2500 species within the predominantly Neotropical and taxonomically problematic tribe Myrteae. Nearly 500 species of Myrteae are endemic to the Caribbean Islands Biodiversity Hotspot, but few have been represented in phylogenetic systematic studies to date. The major goals of this survey are to identify the main lineages of Myrteae present in the Greater Antilles and potential clades for further investigation. Specific objectives are to evaluate the monophyly and placement of the following: (1) the three genera of Myrtaceae considered endemic to the Caribbean Islands (Calyptrogenia, Hottea, Mitranthes); (2) Calycolpus and Pseudanamomis sensu Bisse; and (3) Greater Antillean species of Plinia. To accomplish these aims, species of Myrtaceae representing all genera native to the Greater Antilles were sampled from across the region for placement within previously established phylogenetic frameworks for Myrteae and the large genus Eugenia. In total, 160 terminal taxa of Myrtaceae (89 Caribbean Islands endemics) were analyzed for this study. Phylogenetic inference was conducted by maximum parsimony and Bayesian methods on alignments of DNA sequence data from one nuclear (ITS) and three chloroplast (psbA-trnH, ndhF-rpl32, trnL-trnF) regions. Results of both types of analysis were congruent with each other and with the major clades recovered in previous studies, but some conflict was observed between nuclear and chloroplast regions involving congeneric species. Calycorectes (= Hottea) ekmanii from eastern Cuba was found to be closely related to Calycolpus within subtribe Myrtinae. Subtribes Myrciinae, Pliniinae, Pimentinae (Pimenta and Psidium groups) and Eugeniinae contained other Greater Antillean species. Sampled species of Plinia from Cuba emerged within Myrciaria, and Mitranthes was found to be non-monophyletic. All sampled species of Eugenia endemic to the Caribbean fell within E. sect. Excelsae (including Calycolpus sensu Bisse), E. sect. Racemosae and E. sect. Umbellatae except for E. cycloidea, which was associated with the Old World species of E. sect. Jossinia. Within Eugenia sect. Umbellatae, Caribbean species formed two major clades, designated C1 and C2, containing species of Calyptrogenia and Hottea from southern Hispaniola, a polyphyletic Pseudanamomis sensu Bisse and the Lathberry Clade, a novel group of Eugenia species centered in Puerto Rico and the Virgin Islands. Calyptrogenia and Hottea species from southern Hispaniola are transferred to Eugenia along with Pseudanamomis nipensis, while Mitranthes species are transferred to Myrcia. Two additional combinations are made within Eugenia and Pimenta in accordance with the results, and lectotypes are designated as appropriate.

This is an introductory paper for a Special Issue of Botanical Review devoted to plant biodiversity in the Bahamian archipelago. The papers published in this issue represent some of the contributions presented at a symposium that took place in Nassau in October 30 and 31, 2012 to celebrate the 30 year anniversary of the publication of the \"Flora of the Bahama Archipelago\" by Donovan and Helen Correll. The papers provide insights pertinent to plant conservation challenges, current floristic studies, plant endemicity patterns, plant exploration history, molecular systematic perspectives, and the importance of botanic garden collections for research, horticulture, and education.

Coccothrinax argentata (Arecaceae) occurs in southern Florida, both on the mainland and in the islands of the Florida Keys. However, the palms from the mainland and Keys display morphological differences that led taxonomists to recognize them as distinct species in the past. They are now treated as a single, polymorphic species, but the question remains: Are the morphological differences best explained by genetics or environment? In 1999, seedlings grown from seeds collected from different populations were planted in a common garden in a randomized plot design. In 2007, the first research was published comparing genetics based on ISSRs to morphological measurements. The research from 2007 showed evidence for a genetic explanation, but with poor resolution. Here, we present new genetic data using microsatellite regions (SSRs), in combination with morphological data from more mature palms. The results support the recognition of two taxa, which we propose at the rank of subspecies.

Coccothrinax argentata (Arecaceae) occurs in southern Florida, both on the mainland and in the islands of the Florida Keys. However, the palms from the mainland and Keys display morphological differences that led taxonomists to recognize them as distinct species in the past. They are now treated as a single, polymorphic species, but the question remains: Are the morphological differences best explained by genetics or environment? In 1999, seedlings grown from seeds collected from different populations were planted in a common garden in a randomized plot design. In 2007, the first research was published comparing genetics based on ISSRs to morphological measurements. The research from 2007 showed evidence for a genetic explanation, but with poor resolution. Here, we present new genetic data using microsatellite regions (SSRs), in combination with morphological data from more mature palms. The results support the recognition of two taxa, which we propose at the rank of subspecies.

Gonolobus taylorianus is reported naturalized from Miami-Dade County, Florida. A key and photographs are provided to distinguish the three species of Gonolobus known from the continental United States.