Resource availability and disturbance frequency shape evolution of plant life forms in Neotropical habitats.

Organisms use diverse strategies to thrive in varying habitats. While life history theory partly explains these relationships, the combined impact of resource availability and disturbance frequency on life form strategy evolution has received limited attention. We use Chamaecrista species, a legume plant lineage with a high diversity of plant life forms in the Neotropics, and employ ecological niche modeling and comparative phylogenetic methods to examine the correlated evolution of plant life forms and environmental niches. Chamaephytes and phanerophytes have optima in environments characterized by moderate water and nutrient availability coupled with infrequent fire disturbances. By contrast, annual plants thrive in environments with scarce water and nutrients, alongside frequent fire disturbances. Similarly, geophyte species also show increased resistance to frequent fire disturbances, although they thrive in resource-rich environments. Our findings shed light on the evolution of plant strategies along environmental gradients, highlighting that annuals and geophytes respond differently to high incidences of fire disturbances, with one enduring it as seeds in a resource-limited habitat and the other relying on reserves and root resprouting systems in resource-abundant habitats. Furthermore, it deepens our understanding of how organisms evolve associated with their habitats, emphasizing a constraint posed by low-resource and high-disturbance environments.

Investigating historical drivers of latitudinal gradients in polyploid plant biogeography: A multiclade perspective.

PREMISE: The proportion of polyploid plants in a community increases with latitude, and different hypotheses have been proposed about which factors drive this pattern. Here, we aimed to understand the historical causes of the latitudinal polyploidy gradient using a combination of ancestral state reconstruction methods. Specifically, we assessed whether (1) polyploidization enables movement to higher latitudes (i.e., polyploidization precedes occurrences in higher latitudes) or (2) higher latitudes facilitate polyploidization (i.e., occurrence in higher latitudes precedes polyploidization). METHODS: We reconstructed the ploidy states and ancestral niches of 1032 angiosperm species at four paleoclimatic time slices ranging from 3.3 million years ago to the present, comprising taxa from four well-represented clades: Onagraceae, Primulaceae, Solanum (Solanaceae), and Pooideae (Poaceae). We used ancestral niche reconstruction models alongside a customized discrete character evolution model to allow reconstruction of states at specific time slices. Patterns of latitudinal movement were reconstructed and compared in relation to inferred ploidy shifts. RESULTS: No single hypothesis applied equally well across all analyzed clades. While significant differences in median latitudinal occurrence were detected in the largest clade, Poaceae, no significant differences were detected in latitudinal movement in any clade. CONCLUSIONS: Our preliminary study is the first to attempt to connect ploidy changes to continuous latitudinal movement, but we cannot favor one hypothesis over another. Given that patterns seem to be clade-specific, more clades must be analyzed in future studies for generalities to be drawn.

Towards a species-level phylogeny for Neotropical Myrtaceae: Notes on topology and resources for future studies.

PREMISE: Increasingly complete phylogenies underpin studies in systematics, ecology, and evolution. Myrteae (Myrtaceae), with ~2700 species, is a key component of the exceptionally diverse Neotropical flora, but given its complicated taxonomy, automated assembling of molecular supermatrices from public databases often lead to unreliable topologies due to poor species identification. METHODS: Here, we build a taxonomically verified molecular supermatrix of Neotropical Myrteae by assembling 3909 published and 1004 unpublished sequences from two nuclear and seven plastid molecular markers. We infer a time-calibrated phylogenetic tree that covers 712 species of Myrteae (~28% of the total diversity in the clade) and evaluate geographic and taxonomic gaps in sampling. RESULTS: The tree inferred from the fully concatenated matrix mostly reflects the topology of the plastid data set and there is a moderate to strong incongruence between trees inferred from nuclear and plastid partitions. Large, species-rich genera are still the poorest sampled within the group. Eastern South America is the best-represented area in proportion to its species diversity, while Western Amazon, Mesoamerica, and the Caribbean are the least represented. CONCLUSIONS: We provide a time-calibrated tree that can be more reliably used to address finer-scale eco-evolutionary questions that involve this group in the Neotropics. Gaps to be filled by future studies include improving representation of taxa and areas that remain poorly sampled, investigating causes of conflict between nuclear and plastid partitions, and the role of hybridization and incomplete lineage sorting in relationships that are poorly supported.

Climbing mechanisms and the diversification of neotropical climbing plants across time and space.

Climbers germinate on the ground but need external support to sustain their stems, which are maintained attached to supports through modified organs, that is, climbing mechanisms. Specialized climbing mechanisms have been linked to higher diversification rates. Also, different mechanisms may have different support diameter restrictions, which might influence climbers' spatial distribution. We test these assumptions by linking climbing mechanisms to the spatiotemporal diversification of neotropical climbers. A dataset of climbing mechanisms is presented for 9071 species. WCVP was used to standardize species names, map geographical distributions, and estimate diversification rates of lineages with different mechanisms. Twiners appear concentrated in the Dry Diagonal of South America and climbers with adhesive roots in the Chocó region and Central America. However, climbing mechanisms do not significantly influence the distribution of neotropical climbers. Also, we found no strong support for correlations between specialized climbing mechanisms and higher diversification rates. Climbing mechanisms do not strongly impact the spatiotemporal diversification of neotropical climbers on a macroevolutionary scale. We argue that the climbing habit is a synnovation, meaning the spatiotemporal diversification it promotes is due to the sum effect of all the habit's traits rather than isolated traits, such as climbing mechanisms.

The evolutionary responses of life-history strategies to climatic variability in flowering plants.

The evolution of annual or perennial strategies in flowering plants likely depends on a broad array of temperature and precipitation variables. Previous documented climate life-history correlations in explicit phylogenetic frameworks have been limited to certain clades and geographic regions. To gain insights which generalize to multiple lineages we employ a multi-clade approach analyzing 32 groups of angiosperms across eight climatic variables. We utilize a recently developed method that accounts for the joint evolution of continuous and discrete traits to evaluate two hypotheses: annuals tend to evolve in highly seasonal regions prone to extreme heat and drought; and annuals tend to have faster rates of climatic niche evolution than perennials. We find that temperature, particularly highest temperature of the warmest month, is the most consistent climatic factor influencing the evolution of annual strategy in flowering plants. Unexpectedly, we do not find significant differences in rates of climatic niche evolution between perennial and annual lineages. We propose that annuals are consistently favored in areas prone to extreme heat due to their ability to escape heat stress as seeds, but they tend to be outcompeted by perennials in regions where extreme heat is uncommon or nonexistent.

A trait-based approach to determining principles of plant biogeography.

Lineage-specific traits determine how plants interact with their surrounding environment. Unrelated species may evolve similar phenotypic characteristics to tolerate, persist in, and invade environments with certain characteristics, resulting in some traits becoming relatively more common in certain types of habitats. Analyses of these general patterns of geographical trait distribution have led to the proposal of general principles to explain how plants diversify in space over time. Trait-environment correlation analyses quantify to what extent unrelated lineages have similar evolutionary responses to a given type of habitat. In this synthesis, I give a short historical overview on trait-environment correlation analyses, from some key observations from classic naturalists to modern approaches using trait evolution models, large phylogenies, and massive data sets of traits and distributions. I discuss some limitations of modern approaches, including the need for more realistic models, the lack of data from tropical areas, and the necessary focus on trait scoring that goes beyond macromorphology. Overcoming these limitations will allow the field to explore new questions related to trait lability and niche evolution and to better identify generalities and exceptions in how plants diversify in space over time.

Analysis of Clostridioides difficile Infection in Children with Diarrhea in Two Hospitals in Southern Brazil.

Clostridioides difficile infection (CDI) has been increasingly observed in children, but there is a lack of epidemiological and molecular data on CDI in Latin America. This prospective cohort study aimed to investigate the role of CDI in children with diarrhea. It included 105 children with antimicrobial-associated diarrhea (AAD) and analyzed the molecular characteristics of strains isolated from two hospitals in southern Brazil between 2017 and 2020. Fecal samples from the participants were tested for glutamate dehydrogenase (GDH) and A/B toxins using a rapid enzyme immunoassay. GDH-positive samples underwent automated real-time polymerase chain reaction and toxigenic culture. Toxigenic C. difficile isolates were selected for whole genome sequencing. Out of the 105 patients, 14 (13.3%) met the criteria for CDI. Children with a history of previous CDI and the presence of mucus in their stool were more likely to have CDI. Metronidazole was the most used treatment (71.4%), and three patients (23.1%) experienced CDI recurrence (rCDI). Although the number of sequenced isolates was limited, a wide diversity of sequence types (ST) was observed. In addition to toxin genes (tcdA, tcdB, cdtA, and cdtB), the isolates also exhibited virulence factors involved in adhesion (cwp66, groEL, slpA, fbpA/fbp68) and immune evasion (rmlA, rmlB, rmlC, gnd, rfbA-1), along with multiple resistance factors (gyrA mutation, norA, ermB, dfrF, and vanG). These findings highlight the prevalence and recurrence of CDI among hospitalized children. Longitudinal studies are needed to better understand the characteristics of CDI-associated diarrhea and its impact on the healthcare system in this population.

Retiring "Cradles" and "Museums" of Biodiversity.

In 1974, G. Ledyard Stebbins provided a metaphor illustrating how spatial gradients of biodiversity observed today are by-products of the way environment-population interactions drive species diversification through time. We revisit the narrative behind Stebbins's "cradles" and "museums" of biodiversity to debate two points. First, the usual high-speciation versus low-extinction and tropical versus temperate dichotomies are oversimplifications of the original metaphor and may obscure how gradients of diversity are formed. Second, the way in which we use modern gradients of biodiversity to interpret the potential historical processes that generated them are often still biased by the reasons that motivated Stebbins to propose his original metaphor. Specifically, the field has not yet abandoned the idea that species-rich areas and "basal lineages" indicate centers of origin, nor has it fully appreciated the role of traits as regulators of environment-population dynamics. We acknowledge that the terms "cradles" and "museums" are popular in the literature and that terminologies can evolve with the requirements of the field. However, we also argue that the concepts of cradles and museums have outlived their utility in studies of biogeography and macroevolution and should be replaced by discussions of actual processes at play.

Diversity, phylogeny and evolution of the rapidly evolving genus Psidium L. (Myrtaceae, Myrteae).

BACKGROUND AND AIMS: Psidium is the fourthth largest genus of Myrtaceae in the Neotropics. Psidium guajava is widely cultivated in the tropics for its edible fruit. It is commercially under threat due to the disease guava decline. Psidium cattleyanum is one of the 100 most invasive organisms in the world. Knowledge of the phylogenetic relationships within Psidium is poor. We aim to provide a review of the biology, morphology and ecology of Psidium, a phylogenetic tree, an infrageneric classification and a list of species. METHODS: Morphological and geographic data were obtained by studying Psidium in herbaria and in the field between 1988 and 2020. Forty-six herbaria were visited personally. A database of approx. 6000 specimens was constructed, and the literature was reviewed. Thirty species (about a third of the species in the genus) were sampled for molecular phylogenetic inference. Two chloroplast (psbA-trnH and ndhF) and two nuclear (external transcribed spacer and internal transcribed spacer) regions were targeted. Phylogenetic trees were constructed using maximum likelihood (ML; RaxML) and Bayesian inference (BI; MrBayes). KEY RESULTS: Psidium is a monophyletic genus with four major clades recognized as sections. Section Psidium (ten species), to which P. guajava belongs, is sister to the rest of the genus; it is widespread across the Neotropics. Section Obversifolia (six species; restricted to the Brazilian Atlantic Forest), which includes P. cattleyanum, is sister to the innermost clade composed of sister sections Apertiflora (31 species; widespread but most diverse in the Brazilian Atlantic Forest) + Mitranthes (26 species; widespread in dry forests and probably diverse in the Caribbean). Characters associated with diversification within Psidium are discussed. CONCLUSIONS: Research on pre-foliation, colleters, leaf anatomy, leaf physiology, staminal development, placentation and germination associated with the anatomy of the opercular plug is desirable. Studies are biased towards sections Psidium and Obversifolia, with other sections poorly known.

Moyamoya associated with Turner syndrome in a patient with type 2 spinocerebellar ataxia-Occam's razor or Hickam's dictum: a case report.

BACKGROUND: Turner syndrome (TS) is a rare condition associated with a completely or partially missing X chromosome that affects 1 in 2500 girls. TS increases the risk of autoimmune diseases, including Graves' disease (GD). Moyamoya disease is a rare cerebral arteriopathy of unknown etiology characterized by progressive bilateral stenosis of the internal carotid artery and its branches. Both TS and GD have been associated with Moyamoya. Type 2 spinocerebellar ataxia (SCA2) is an autosomal dominant cerebellar ataxia caused by a CAG repeat expansion in ATXN2. We present the first case of Moyamoya syndrome in a patient with a previous diagnosis of TS and GD who tested positive for SCA2 and had imaging findings compatible with an overlap of SCA2 and Moyamoya. CASE PRESENTATION: A 43-year-old woman presented with mild gait imbalance for 2 years. Her family history was positive for type 2 spinocerebellar ataxia (SCA2). She had been diagnosed with Turner Syndrome (45,X) and Graves disease three years before. Brain MRI revealed bilateral frontal and parietal cystic encephalomalacia in watershed zones, atrophy of pons, middle cerebellar peduncles and cerebellum. MR angiography showed progressive stenosis of both internal carotid arteries with lenticulostriate collaterals, suggestive of Moya-Moya disease. Molecular analysis confirmed the diagnosis of SCA2. CONCLUSIONS: With increased availability of tools for genetic diagnosis, physicians need to be aware of the possibility of a single patient presenting two or more rare diseases. This report underscores the modern dilemmas created by increasingly accurate imaging techniques and available and extensive genetic testing.

Normal pressure hydrocephalus associated with COVID-19 infection: a case report.

BACKGROUND: COVID-19 is a pandemic disease responsible for many deaths worldwide. Many neurological manifestations have been described. We report a case of normal pressure hydrocephalus (NPH) 2 months after acute COVID19 infection, in a patient without other risk factors. CASE PRESENTATION: A 45-year-old male patient presented an 8-month history of progressive gait disorder and cognitive impairment after being hospitalized for SARS-CoV-2 infection. Magnetic resonance imaging (MRI) was compatible with NPH. A spinal tap test was positive and there was progressive improvement after shunting, with complete resolution of symptoms. CONCLUSION: Other infections such as syphilis, cryptococcosis and Lyme disease have been associated with NPH. Possible mechanisms for NPH after COVID include disruption of choroid plexus cells by direct viral invasion or as a result of neuroinflammation and cytokine release and hypercoagulability leading to venous congestion and abnormalities of CSF flow. Given the significance of NPH as a cause of reversible dementia, it is important to consider the possibility of a causal association with COVID19 and understand the mechanisms behind this association.

Covid-19 post-infectious acute transverse myelitis responsive to corticosteroid therapy: report of two clinical cases.

SARS-COV-2 infection has affected millions of individuals with a wide range of clinical manifestations, including central and peripheral nervous systems through several mechanisms. A rare but potentially severe manifestation of this virus is transverse myelitis. Herein, we report on two patients who developed paraparesis, sensory deficit, and autonomic changes on the tenth day after infection by COVID-19. A 27-year-old man, previously healthy, had symptoms of COVID-19 confirmed by oropharyngeal and nasopharyngeal swab tests. On the tenth day of symptoms, the patient started to experience acute paraparesis, urinary retention, constipation, and hypoesthesia up to the T4 level. The second patient is a 50-year-old man, previously healthy, who had symptoms of the flu-like syndrome. The diagnosis of COVID-19 infection was confirmed by oropharyngeal and nasopharyngeal swab tests. On the tenth day of symptoms, the patient started to experience paraparesis, urinary incontinence, and hypoesthesia up to the T6 level. The neuroimaging and cerebrospinal fluid (CSF) analysis of both patients confirmed acute transverse myelitis after COVID-19 infection. High-dose corticosteroid therapy was started, and both patients showed rapid recovery from their deficits. Although rare, post-infectious transverse myelitis may be related to SARS-COV-2 infection and should be quickly recognized. Although controlled studies are needed, treatment with corticosteroid therapy in high doses was effective in these patients.

Evolutionary lability in floral ontogeny affects pollination biology in Trimezieae.

PREMISE: There is little direct evidence linking floral development and pollination biology in plants. We characterize both aspects in plain and ornamented flowers of Trimezieae (Iridaceae) to investigate how changes in floral ontogeny may affect their interactions with pollinators through time. METHODS: We examined floral ontogeny in 11 species and documented pollination biology in five species displaying a wide range of floral morphologies. We coded and reconstructed ancestral states of flower types over the tribal phylogeny to estimate the frequency of transition between different floral types. RESULTS: All Trimezieae flowers are similar in early floral development, but ornamented flowers have additional ontogenetic steps compared with plain flowers, indicating heterochrony. Ornamented flowers have a hinge pollination mechanism (newly described here) and attract more pollinator guilds, while plain flowers offer less variety of resources for a shorter time. Although the ornamented condition is plesiomorphic in this clade, shifts to plain flowers have occurred frequently and abruptly during the past 5 million years, with some subsequent reversals. CONCLUSIONS: Heterochrony has resulted in labile morphological changes during flower evolution in Trimezieae. Counterintuitively, species with plain flowers, which are endemic to the campo rupestre, are derived within the tribe and show a higher specialization than the ornamented species, with the former being visited by pollen-collecting bees only.

A nuclear phylogenomic study of the angiosperm order Myrtales, exploring the potential and limitations of the universal Angiosperms353 probe set.

PREMISE: To further advance the understanding of the species-rich, economically and ecologically important angiosperm order Myrtales in the rosid clade, comprising nine families, approximately 400 genera and almost 14,000 species occurring on all continents (except Antarctica), we tested the Angiosperms353 probe kit. METHODS: We combined high-throughput sequencing and target enrichment with the Angiosperms353 probe kit to evaluate a sample of 485 species across 305 genera (76% of all genera in the order). RESULTS: Results provide the most comprehensive phylogenetic hypothesis for the order to date. Relationships at all ranks, such as the relationship of the early-diverging families, often reflect previous studies, but gene conflict is evident, and relationships previously found to be uncertain often remain so. Technical considerations for processing HTS data are also discussed. CONCLUSIONS: High-throughput sequencing and the Angiosperms353 probe kit are powerful tools for phylogenomic analysis, but better understanding of the genetic data available is required to identify genes and gene trees that account for likely incomplete lineage sorting and/or hybridization events.

Fast diversification through a mosaic of evolutionary histories characterizes the endemic flora of ancient Neotropical mountains.

Mountains are among the most biodiverse areas on the globe. In young mountain ranges, exceptional plant species richness is often associated with recent and rapid radiations linked to the mountain uplift itself. In ancient mountains, however, orogeny vastly precedes the evolution of vascular plants, so species richness has been explained by species accumulation during long periods of low extinction rates. Here we evaluate these assumptions by analysing plant diversification dynamics in the campo rupestre, an ecosystem associated with pre-Cambrian mountaintops and highlands of eastern South America, areas where plant species richness and endemism are among the highest in the world. Analyses of 15 angiosperm clades show that radiations of endemics exhibit fastest rates of diversification during the last 5 Myr, a climatically unstable period. However, results from ancestral range estimations using different models disagree on the age of the earliest in situ speciation events and point to a complex floristic assembly. There is a general trend for higher diversification rates associated with these areas, but endemism may also increase or reduce extinction rates, depending on the group. Montane habitats, regardless of their geological age, may lead to boosts in speciation rates by accelerating population isolation in archipelago-like systems, circumstances that can also result in higher extinction rates and fast species turnover, misleading the age estimates of endemic lineages.

Is dispersal mode a driver of diversification and geographical distribution in the tropical plant family Melastomataceae?

Species of plants with different life history strategies may differ in their seed dispersal mechanisms, impacting their distribution and diversification patterns. Shorter or longer distance dispersal is favored by different dispersal modes, facilitating (or constraining) population isolation, which can, in turn, impact speciation and species range sizes. While these associations are intuitive, few studies have explicitly tested these hypotheses for large clades of angiosperms. The plant family Melastomataceae is found on disparate habitats with different dispersal modes, representing a good model to address these questions. In this study, we reconstruct the phylogeny of Melastomataceae and gather data on their dispersal mode and range size to test the impact of dispersal mode on diversification and range size evolution. We found that abiotic dispersal is ancestral in the family, while biotic dispersal evolved multiple times. Species richness distribution is very similar across dispersal modes, although abiotically dispersed species tend to be relatively more diverse in seasonal environments. Range sizes across dispersal modes are not significantly different, although biotically dispersed species have slightly wider distributions. Model comparisons indicate that factors other than dispersal mode might have driven diversification heterogeneity. We did not find evidence for the role of dispersal mode driving diversification rates or range size in the Melastomataceae, suggesting a complex macroevolutionary scenario for this diverse angiosperm family. The bulk of changes to biotic dispersal coinciding with an increase in passerine diversification suggests a possible "past" key innovation in Melastomataceae. Future studies should investigate the role of other diversification drivers in the family and the relatively higher diversity of abiotically dispersed species in open habitats.

Biogeography and early diversification of Tapinotaspidini oil-bees support presence of Paleocene savannas in South America.

Worldwide distributed tropical savannas were established only in the Miocene, with climatic cooling and rise of C4 grasses. However, there is evidence for an earlier presence of savanna-like vegetation in southern parts of South America. Here we investigated the biogeographic history of a clade of solitary bees which have endemic groups in areas covered by savannas and other types of open vegetation as well as forested areas. We hypothesized that these bees originated in savanna-like biomes and that shifts to forested areas and floral host shifts increased species diversification along their evolutionary history. We reconstructed a comprehensive phylogeny for Tapinotaspidini bees based majorly on original DNA sequences. We then used macroevolutionary tools to estimate ancestral range area and reconstructed ancestral habitat (open versus forested) and host plant association to analyze the effects of shifts in vegetation type and flower hosts on their diversification. Tapinotaspidini bees originated in the Paleocene and in a savanna-type, Cerrado-like, which is reinforced by reconstruction of open vegetation as the most probable ancestral area, thus bringing additional evidence to a much earlier origin of this vegetation type in South America. Shifts to forested areas occurred at least three times in a period of 30 Ma and were responsible for slight increases in diversification rates. Malpighiaceae is the ancestral floral host; host broadening occurred only in the Miocene and at least in three occasions. Host shifts, i.e. from Malpighiaceae to other oil families, occurred in the Eocene and Miocene. Both host broadening and host shifts did not significantly alter diversification rates, however exploitation of other oil sources were important in occupying new habitats. The link between biomes and host plant shifts and changes in diversification rate brings us additional insights into the evolution of bees and associated flora in South America.

Floral uniformity through evolutionary time in a species-rich tree lineage.

Changes in floral morphology are expected across evolutionary time and are often promoted as important drivers in angiosperm diversification. Such a statement, however, is in contrast to empirical observations of species-rich lineages that show apparent conservative floral morphologies even under strong selective pressure to change from their environments. Here, we provide quantitative evidence for prolific speciation despite uniform floral morphology in a tropical species-rich tree lineage. We analyse floral disparity in the environmental and phylogenetic context of Myrcia (Myrtaceae), one of the most diverse and abundant tree genera in Neotropical biomes. Variation in floral morphology among Myrcia clades is exceptionally low, even among distantly related species. Discrete floral specialisations do occur, but these are few, present low phylogenetic signal, have no strong correlation with abiotic factors, and do not affect overall macroevolutionary dynamics in the lineage. Results show that floral form and function may be conserved over large evolutionary time scales even in environments full of opportunities for ecological interactions and niche specialisation. Species accumulation in diverse lineages with uniform flowers apparently does not result from shifts in pollination strategies, but from speciation mechanisms that involve other, nonfloral plant traits.

Advanced understanding of phylogenetic relationships, morphological evolution and biogeographic history of the mega-diverse plant genus Myrcia and its relatives (Myrtaceae: Myrteae).

Myrcia is the largest exclusively Neotropical genus of the plant family Myrtaceae with c. 770 species. Although several studies have elucidated the relationships within particular sections of the genus, to date no phylogeny has been produced that includes a broad taxonomic and geographic representation. Here we present a phylogenetic hypothesis of Myrcia and close relatives comprising 253 species and based on two nuclear and seven plastid markers. We combine previously available sequence data with 234 new sequences of the genus Myrcia for this study. We use this phylogeny to investigate the evolution of selected morphological traits and to infer the biogeographic history of the genus. Our results yield a highly supported phylogenetic tree where the Myrceugenia group is sister to the Myrcia and Plinia groups. Five Myrcia species previously considered unplaced emerge in a newly circumscribed clade. The monophyly of two Myrcia sections previously considered uncertain, Aulomyrcia and Gomidesia, are confirmed with strong support. Flowers with free calyx lobes, 2-locular ovaries, and anthers with symmetrical thecae are ancestral features of Myrcia. The Myrcia sect. Gomidesia is highly supported and recovered as monophyletic, with asymmetric anthers that retain their curvature after dehiscence as a morphological synapomorphy. The Atlantic Forest is the most likely ancestral area of the genus and most of its internal clades, from where multiple lineages colonized different regions of South and Central America, in particular the Brazilian Cerrado through multiple unidirectional range expansions. The southern Atlantic Forest is the ancestral area for Myrcia sect. Gomidesia, with lineages reaching the northern Atlantic Forest, Cerrado, Yungas, and other savanna vegetation of South America. Our results provide a solid backbone for further evolutionary and taxonomic work and clarify several previously uncertain relationships in this mega-diverse plant group, and shed light on its geographical range evolution.

Calyx (con)fusion in a hyper-diverse genus: Parallel evolution of unusual flower patterns in Eugenia (Myrtaceae).

Eugenia has a pantropical distribution and comprises ca. 1000 species found mostly in the Neotropics. Recent DNA based phylogenies show that unusual flower morphology of 'eugenioid' collections, e.g. fused calices that open by tearing, consistently emerged within Eugenia. These results emphasize a demand to revaluate flower morphology in a phylogenetic context within the genus. A reassessment of calyx fusion in Eugenia and traditionally related genera is here focused on clarification of the systematic relevance of this apparently recurrent characteristic. Twenty-four Eugenia species with some level of calyx fusion in the bud were newly used (one nuclear and four plastid markers) in conjunction with a representative sample of previously sequenced species to recover a time-calibrated Eugenia phylogeny of 86 accessions. Development of the fused calyx was analysed using scanning electron microscopy, differing patterns were re-coded and subsequently phylogenetic character reconstruction was performed. Eugenia was recovered as monophyletic including the traditionally segregated genera Calycorectes and Catinga. Ancestral character reconstruction uncovered free calyx lobes as the ancestral condition. Five development patterns leading to calyx fusion are reported in Eugenia including species with apparently six petals, which contrast with the standard tetramerous flowers. This condition is interpreted as the petaloid pattern, where two external fused calyx lobes cover the bud while two internal calyx lobes are free and petaloid. The fused calyx condition is homoplastic and evolved independently, several times in Eugenia, as did the different development patterns. Data presented here show that systematic incongruence resulting from multiple, independent origins of the fused calyx in Eugenia is further aggravated by an inability to distinguish parallelism and convergence within the recovered patterns.