Eve Lucas

Plant Diversity Hotspots in the Atlantic Coastal Forests of Brazil

Plant-diversity hotspots on a global scale are well established, but smaller local hotspots within these must be identified for effective conservation of plants at the global and local scales. We used the distributions of endemic and endemic-threatened species of Myrtaceae to indicate areas of plant diversity and conservation importance within the Atlantic coastal forests (Mata Atlântica) of Brazil. We applied 3 simple, inexpensive geographic information system (GIS) techniques to a herbarium specimen database: predictive species-distribution modeling (Maxent); complementarity analysis (DIVA-GIS); and mapping of herbarium specimen collection locations. We also considered collecting intensity, which is an inherent limitation of use of natural history records for biodiversity studies. Two separate areas of endemism were evident: the Serra do Mar mountain range from Paraná to Rio de Janeiro and the coastal forests of northern Espírito Santo and southern Bahia. We identified 12 areas of approximately 35 km(2) each as priority areas for conservation. These areas had the highest species richness and were highly threatened by urban and agricultural expansion. Observed species occurrences, species occurrences predicted from the model, and results of our complementarity analysis were congruent in identifying those areas with the most endemic species. These areas were then prioritized for conservation importance by comparing ecological data for each.

Suprageneric phylogenetics of Myrteae, the generically richest tribe in Myrtaceae (Myrtales)

To clarify relationships within the predominantly Neotropical and exclusively fleshy-fruited Myrteae (49 genera and c. 2,500 species), we provide a phylogenetic hypothesis for evolutionary relationships between 31 of these genera by analyzing nuclear ITS and ETS ribosomal DNA, and plastid psbA-trnH and matK DNA sequences from 75 Myrteae species and 13 outgroup taxa using parsimony and Bayesian inference. Four morphological characters are epitomized on the resulting trees, and biogeographical analyses are also performed. Myrteae are monophyletic, comprising seven clades plus two isolated taxa of unclear relationships. Morphological characters exhibit homoplasy, although in combination are useful for clade diagnosis. Biogeographical analyses are inconclusive regarding the ancestral area of the tribe, but South American colonization before northern radiation via the Andes appears likely. The largest genera, Eugenia and Myrcia s.1., have western and south-eastern South American origins, respectively.

Evolution of exceptional species richness among lineages of fleshy-fruited Myrtaceae

BACKGROUND AND AIMS The angiosperm family Myrtaceae comprises 17 tribes with more than half of the estimated 5500 species being referred to the fleshy-fruited and predominantly rainforest associated Syzygieae and Myrteae. Previous studies suggest that fleshy fruits have evolved separately in these lineages, whereas generally shifts in fruit morphology have been variously implicated in diversification rate shifts among angiosperms. A phylogenetic hypothesis and estimate divergence times for Myrtaceae is developed as a basis to explore the evidence for, and drivers of, elevated diversification rates among the fleshy-fruited tribes of Myrtaceae. METHODS Bayesian phylogenetic analyses of plastid and nuclear DNA sequences were used to estimate intertribal relationships and lineage divergence times in Myrtaceae. Focusing on the fleshy-fruited tribes, a variety of statistical approaches were used to assess diversification rates and diversification rate shifts across the family. KEY RESULTS Analyses of the sequence data provide a strongly supported phylogenetic hypothesis for Myrtaceae. Relative to previous studies, substantially younger ages for many of the clades are reported, and it is argued that the use of flexible calibrations to incorporate fossil data provides more realistic divergence estimates than the use of errorless point calibrations. It is found that Syzygieae and Myrteae have experienced elevated diversification rates relative to other lineages of Myrtaceae. Positive shifts in diversification rate have occurred separately in each lineage, associated with a shift from dry to fleshy fruit. CONCLUSIONS Fleshy fruits have evolved independently in Syzygieae and Myrteae, and this is accompanied by exceptional diversification rate shifts in both instances, suggesting that the evolution of fleshy fruits is a key innovation for rainforest Myrtaceae. Noting the scale dependency of this hypothesis, more complex explanations may be required to explain diversification rate shifts occurring within the fleshy-fruited tribes, and the suggested phylogenetic hypothesis provides an appropriate framework for this undertaking.

Phylogenetic patterns in the fleshy-fruited Myrtaceae – preliminary molecular evidence

Abstract.A phylogenetic study of selected fleshy-fruited genera of the Myrtaceae was conducted using sequences from the ITS region of nuclear DNA and the psbA-trnH region of plastid DNA. Studies to date have suggested that the fleshy-fruited state has arisen on several occasions in the Myrtaceae. The previously accepted and predominantly Neotropical tribe Myrteae has traditionally been divided into three groups, the subtribes Myrtinae, Eugeniinae and Myrciinae. This subtribal arrangement is analysed in detail here for the first time. The monophyly of the tribe and subtribes are tested and relationships of the genera within them, in particular those of the Myrciinae and anomalous genera sometimes associated with it, are discussed. Combined analyses of these two DNA regions revealed 40 shortest trees, all of which resolve Myrteae (excluding the Acmena group) as monophyletic. Myrciinae appears to be monophyletic whereas Myrtinae and Eugeniinae appear polyphyletic. The phylogenetic positions and relationships of the anomalous genera Myrceugenia,Luma and Blepharocalyx are unclear, but Myrceugenia is never included within the Myrciinae s.str. A Myrciinae s.str. clade emerges within which Myrcia,Calyptranthes and Marlierea appear polyphyletic. Clades emerge, however, that may reflect some natural groupings within the subtribe.

Phylogenetics, Morphology, and Evolution of the Large Genus Myrcia s.l. (Myrtaceae)

Phylogenetic relationships of Myrcia s.l., the most species-rich tree genus in the Brazilian cerrado and Atlantic forests, are reconstructed by analysis, with parsimony and Bayesian inference, of four plastid regions (psbA-trnH intergenic spacer, trnL intron, trnL-F intergenic spacer, and matK exon) and the external and internal transcribed spacer regions of nuclear ribosomal DNA. The resulting phylogenetic hypothesis is evaluated in conjunction with key morphological characters and abiotic factors suggested to have influenced the group’s current distribution. Some lineages identified by previous classifications are supported; others with morphological and/or ecological correspondence are recognized for the first time. Sequence divergence levels provide good resolution of relationships within but not between the main clades of Myrcia s.l. The previously recognized genera Calyptranthes and Gomidesia are shown to be monophyletic, whereas Marlierea is shown not to be; all are nested within paraphyletic Myrcia. A new subgeneric classification is required. An interpretation of the origins of Myrcia s.l. and potential causes of speciation in the group is made on the basis of recently published data and accepted geological events.

A preliminary phylogenetic analysis of Eugenia (Myrtaceae: Myrteae), with a focus on Neotropical species

Summary. A first phylogenetic hypothesis of Neotropical Eugenia, including associated genera and species from Africa and the Pacific was produced using DNA sequence data from the nuclear (ITS, ETS) and plastid (psbA-trnH) genomes. This analysis aimed to investigate the validity of the currently recognised infrageneric groups within Eugenia as well as suites of supporting morphological characters, to determine relationships between groups and produce a framework for future taxonomic research. A total of 70 samples were analysed and the resulting topology confirms the inclusion of Neotropical genera Calycorectes, Hexachlamys, Phyllocalyx and Stenocalyx in Eugenia to preserve the monophyly of Eugenia. Within Eugenia s.l., nine clades are identified as morphologically diagnosable groups and are assigned to two genera (Eugenia and Myrcianthes). Their morphological synapomorphies are discussed. Some lineages identified by previous classifications are also supported. Preliminary phylogenetic results presented here combined with morphology point towards the need for a new subgeneric classification for Eugenia.

Myrteae phylogeny, calibration, biogeography and diversification patterns: Increased understanding in the most species rich tribe of Myrtaceae.

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.

Algrizea (Myrteae, Myrtaceae): A New Genus from the Highlands of Brazil

Abstract The monotypic genus Algrizea is described from the Chapada Diamantina highlands, in Bahia, Brazil, and a new combination, Algrizea macrochlamys, is proposed. This species was well-known from flowering material but fruits and seeds, essential for accurate generic placement, were unknown until 2000. Treated successively as Myrcia, Myrtus, and more recently as Psidium, it combines characters usually considered primitive in the Myrtaceae with an unusual embryo unlike any hitherto described in the Myrtaceae. Morphological and preliminary molecular data suggest that it is best accommodated in the Myrciinae sensu stricto. Algrizea is distinguished by the combination of 3-flowered dichasia, persistent bracteoles, 5 well-developed calyx lobes, bilocular ovaries with 3–6(-8) ovules per locule, seeds 2–3 with membranous, shiny testa, and an embryo in which the hypocotyl assumes an internal position to the unequal, sheathing cotyledons.

Myrtaceae in the Atlantic forest: their role as a ‘model’ group

Myrtaceae is one of the richest families in the Atlantic Forest, a priority biodiversity hotspot that continues to be highly threatened, subject to rapid urbanisation and high levels of resource exploitation. Authors have suggested that individual lineages can be used as models to study biome evolution and ecology and to provide data for conservation planning in these areas. Here we review how Myrtaceae fit the ‘model’ criteria and examine the family’s distribution throughout the Brazilian Atlantic Forest answering the questions: What is the ecological representation of Myrtaceae in the Atlantic Forest?; What is the current taxonomic situation of Myrtaceae in the biome?; What is the current phylogenetic understanding in the family?; Does the historical timeframe of the lineage coincide with that of the biome?; Can Myrtaceae be used to discuss species diversity hotspots within the Atlantic forests?; What is the role of Myrtaceae in conservation strategy? And finally, Can Myrtaceae be used as a ‘model’ taxon? The concept of the ‘model taxon’ is also discussed. The review concludes that taxonomic and phlyogenetic understanding in Myrtaceae are rapidly increasing, giving hope that taxonomic stability, easy species identification and management are realistic in a way unthinkable only a few decades ago. Myrtaceae function well as a ‘model’ within the Atlantic forest but fit some criteria better than others. Taxa can qualify as ‘models’ representing different times and pressures in the history of a given biome; each tells its own story. For future ‘model’ group studies to have maximum impact and implementation for evolutionary studies and conservation strategy, synthetic studies of multiple ‘model’ groups using multiple approaches are required; only then can a predictive understanding of past and future processes in the biomes concerned, be glimpsed.

Two new species of Myrtaceae (Myrteae) from northern South America

Two new species of Myrtaceae are described and illustrated. Campomanesia cucullata is a tree from Monte Alegre, Pará, in the Brazilian Amazon. It is most similar to C. lineatifolia, from which it differs by being leafless when flowering, and by having densely congested and very small flowers. Myrcianthes monteucalyptoides is a tree from Tarma, Junín, in Central Peru. It is most similar to Myrcianthes myrsinoides, but the new species differs by a combination of medium-sized, somewhat revolute, broadly-acuminate leaves, and by the solitary, pentamerous flowers with delicate pedicels.