ABSTRACT
Species conservation assessments using the criteria outlined by the International Union for the Conservation of Nature Red List can be compromised by limited data availability. Species-rich tropical plant taxa with numerous microendemics are particularly problematic. This study focusses on the Begonia flora of the Indonesian island of Sulawesi, comprised of 65 herbaceous species mainly found in rainforest habitats. Sixty-two species are Sulawesi endemics, including 20 species restricted to limestone karst landscapes. Forty-eight species are represented by fewer than 10 herbarium collections. Here, we outline and discuss an approach that, despite these data limitations, allows meaningful conservation assessments by integrating analyses of occurrences, data primarily based on remote sensing approaches, including forest landscape integrity, forest cover loss, and land cover, and extent of suitable habitat estimation. The results indicate that most Sulawesi Begonia species are narrow endemics whose rainforest habitats have substantially deteriorated in the last two decades: 27 species are assessed as Critically Endangered, 24 as Endangered, six as Vulnerable, five as Least Concern, and three species are Data Deficient. Conservation action, including extension of the protected area network in Sulawesi with emphasis on areas of old-growth forest and limestone karst landscapes, and strengthening of ex-situ living collections, is recommended.
Subject(s)
Begoniaceae , Conservation of Natural Resources , Endangered Species , Conservation of Natural Resources/methods , Indonesia , Begoniaceae/physiology , Ecosystem , Rainforest , Biodiversity , Tropical ClimateABSTRACT
Clarifying the evolutionary processes underlying species diversification and adaptation is a key focus of evolutionary biology. Begonia (Begoniaceae) is one of the most species-rich angiosperm genera with c. 2000 species, most of which are shade-adapted. Here, we present chromosome-scale genome assemblies for four species of Begonia (B. loranthoides, B. masoniana, B. darthvaderiana and B. peltatifolia), and whole genome shotgun data for an additional 74 Begonia representatives to investigate lineage evolution and shade adaptation of the genus. The four genome assemblies range in size from 331.75 Mb (B. peltatifolia) to 799.83 Mb (B. masoniana), and harbor 22 059-23 444 protein-coding genes. Synteny analysis revealed a lineage-specific whole-genome duplication (WGD) that occurred just before the diversification of Begonia. Functional enrichment of gene families retained after WGD highlights the significance of modified carbohydrate metabolism and photosynthesis possibly linked to shade adaptation in the genus, which is further supported by expansions of gene families involved in light perception and harvesting. Phylogenomic reconstructions and genomics studies indicate that genomic introgression has also played a role in the evolution of Begonia. Overall, this study provides valuable genomic resources for Begonia and suggests potential drivers underlying the diversity and adaptive evolution of this mega-diverse clade.
Subject(s)
Begoniaceae , Begoniaceae/genetics , Evolution, Molecular , Genome , Phylogeny , Synteny/geneticsABSTRACT
Prairies in the Pacific Northwest are dominated by perennial bunchgrasses. A Mycena in the citrinomarginata complex was observed to tightly co-occur with bunchgrasses at several prairie study sites. Mapping and spatial statistics showed that it was strongly and significantly associated with Festuca roemeri tussocks. We further found that this fungus is attached to F. roemeri roots (17/17 examined) and both specific primers and next-generation DNA sequencing established that the fungus is in the roots, suggesting that M. citrinomarginata may be endophytic or biotrophic in some contexts, and not simply saprotrophic. These results combined with a literature review indicate that Mycena species are often found as endophytes in grass roots. Given the importance of grasses and grasslands for humans, this ecological association deserves further study.
Subject(s)
Festuca , Agaricales , Grassland , Humans , Northwestern United States , Plant RootsABSTRACT
Malvaceae s.l., the most diverse family within Malvales, includes well-known species of great economic importance like cotton, cacao, and durian. Despite numerous phylogenetic analyses employing multiple markers, relationships between several of its nine subfamilies, particularly within the largest lineage /Malvadendrina, remain unclear. In this study, we attempted to resolve the relationships within the major clades of Malvaceae s.l. using plastid genomes of 48 accessions representing all subfamilies. Maximum likelihood and Bayesian analyses recovered a fully resolved and well-supported topology confirming the split of the family into /Byttneriina (/Grewioideae +/Byttnerioideae) and /Malvadendrina. Within /Malvadendrina, /Helicteroideae occupied the earliest branching position, followed by /Sterculioideae, /Brownlowioideae, /Tiliodeae, and /Dombeyoideae formed a clade sister to /Malvatheca (/Malvoideae +/Bombacoideae), a grouping morphologically supported by the lack of androgynophore. Results from dating analyses suggest that all subfamilies originated during hot or warm phases in the Late Cretaceous to Paleocene. This study presents a well-supported phylogenetic framework for Malvaceae s.l. that will aid downstream revisions and evolutionary studies of this economically important plant family.
Subject(s)
Malvaceae , Phylogeny , Bayes Theorem , Biological EvolutionABSTRACT
The flowering plant family Annonaceae includes important commercially grown tropical crops, but development of promising species is hindered by a lack of genomic resources to build breeding programs. Annonaceae are part of the magnoliids, an ancient lineage of angiosperms for which evolutionary relationships with other major clades remain unclear. To provide resources to breeders and evolutionary researchers, we report a chromosome-level genome assembly of the soursop (Annona muricata). We assembled the genome using 444.32 Gb of DNA sequences (676× sequencing depth) from PacBio and Illumina short-reads, in combination with 10× Genomics and Bionano data (v1). A total of 949 scaffolds were assembled to a final size of 656.77 Mb, with a scaffold N50 of 3.43 Mb (v1), and then further improved to seven pseudo-chromosomes using Hi-C sequencing data (v2; scaffold N50: 93.2 Mb, total size in chromosomes: 639.6 Mb). Heterozygosity was very low (0.06%), while repeat sequences accounted for 54.87% of the genome, and 23,375 protein-coding genes with an average of 4.79 exons per gene were annotated using de novo, RNA-seq and homology-based approaches. Reconstruction of the historical population size showed a slow continuous contraction, probably related to Cenozoic climate changes. The soursop is the first genome assembled in Annonaceae, supporting further studies of floral evolution in magnoliids, providing an essential resource for delineating relationships of ancient angiosperm lineages. Both genome-assisted improvement and conservation efforts will be strengthened by the availability of the soursop genome. As a community resource, this assembly will further strengthen the role of Annonaceae as model species for research on the ecology, evolution and domestication potential of tropical species in pomology and agroforestry.
Subject(s)
Annona , Genome, Plant , Annona/genetics , Chromosomes, Plant , Molecular Sequence Annotation , Plant BreedingABSTRACT
Dispersal syndromes are often defined by reference to fruit traits that are associated with distinct frugivore guilds. Studies rarely examine the relationship between seed traits and frugivores or test the alternative hypothesis that traits are shaped by climatic variables. We assess whether the evolution of seed size and physical defense are correlated with dispersal-related traits and climatic variables in Artabotrys, a fleshy-fruited tropical lineage. Diaspore traits and WorldClim bioclimatic variables were compiled for 43 species. Correlated evolution was evaluated using phylogenetic regression and model-fitting approaches. The best-fitting multioptima Ornstein-Uhlenbeck model suggests that lineages with smooth testa and thin pericarp (SP) have evolved toward smaller seeds with a thinner testa, whereas lineages with rough testa and/or thick pericarp have evolved toward larger seeds with a thicker testa. A smooth testa facilitates spitting and/or swallowing of intact seeds while fruits with thin pericarp may be preferentially consumed by frugivores with less destructive oral processing, enabling lower investment in seed physical defense in SP lineages. Moreover, small seeds are more likely to be swallowed intact with a food bolus. The effect of climate on seed size and physical defense is equivocal and warrants further investigation.
Subject(s)
Annonaceae/anatomy & histology , Biological Evolution , Food Chain , Fruit/anatomy & histology , Seeds/anatomy & histology , Selection, Genetic , Annonaceae/physiologyABSTRACT
BACKGROUND: Factors that predict melanoma recurrence after a negative sentinel lymph node biopsy (SLNB) are not well-defined. We evaluated melanoma recurrence patterns, factors prognostic for recurrence, and the impact of recurrence on outcomes after a negative SLNB. METHODS: The Sentinel Lymph Node Working Group database was evaluated from 1996 to 2016 for negative SLNB melanoma patients. Clinicopathologic characteristics were correlated with recurrence, overall survival (OS), and melanoma-specific survival (MSS). RESULTS: Median follow-up was 32.1 months. Recurrences developed in 558 of 5351 negative SLN patients (10.4%). First-site of recurrence included a local or in-transit recurrence (LITR) in 221 cases (4.1%), nodal recurrence (NR) in 109 cases (2%), and distant recurrence (DR) in 220 cases (4.1%). On multivariable analysis, age, thickness, head/neck or lower extremity primary, and microsatellitosis significantly predicted for an LITR as first-site. Having an LITR as first-site significantly predicted for a subsequent NR and DR, and significantly predicted for worse OS and MSS. Furthermore, thickness and head/neck or lower extremity primary significantly predicted for an NR as first-site, while a prior LITR significantly predicted for a subsequent NR. Factors significantly predictive for a DR included thickness, head/neck or trunk primary, ulceration, and lymphovascular invasion. Patients with any type of locoregional recurrence were at higher risk for a DR. CONCLUSIONS: Recurrences occur in 10.4% of negative SLN patients, with LITR and DR being the most common types. Importantly, having an LITR significantly predicts for a subsequent NR and DR, and is prognostic for worse survival after a negative SLNB.
Subject(s)
Head and Neck Neoplasms/pathology , Lymph Node Excision/mortality , Melanoma/pathology , Neoplasm Recurrence, Local/pathology , Sentinel Lymph Node Biopsy/mortality , Sentinel Lymph Node/pathology , Adolescent , Adult , Aged , Aged, 80 and over , Databases, Factual , Female , Follow-Up Studies , Head and Neck Neoplasms/surgery , Humans , Male , Melanoma/surgery , Middle Aged , Neoplasm Invasiveness , Neoplasm Recurrence, Local/surgery , Predictive Value of Tests , Retrospective Studies , Sentinel Lymph Node/surgery , Survival Rate , Young AdultABSTRACT
BACKGROUND: Robot-assisted thoracoscopic lobectomy has been shown to be a safe approach to pulmonary lobectomy. This study sought to define, mathematically, the learning curve for RATS lobectomy. METHODS: Patients undergoing robot-assisted thoracoscopic lobectomy at a single institution from 2010 through 2016 were considered. Covariates included patient demographics, comorbidities, operating time, length of stay, estimated blood loss, and postoperative complications. A cumulative sum analysis of operating time was performed to define the learning curve. RESULTS: A total of 101 patients were included. Three distinct phases of the learning curve were identified: cases 1-22, cases 23-63, and cases 64-101. There was a statistically significant difference in operating time and estimated blood loss between phases 1 and 2 (P < .05, Pâ¯=â¯.016, respectively) and between phases 1 and 3 (P < .05, Pâ¯=â¯.006, respectively). There was no statistically significant difference in comorbidities, chest tube duration, length of stay, postoperative complications, or conversion rate across the learning curve. CONCLUSION: Based on operating time, the learning curve for robot-assisted thoracoscopic lobectomy is 22 cases, with mastery achieved after 63 cases. No differences in length of stay, chest tube duration, conversion rate, or complication rate were observed in the learning curve. Other factors not measured in this study may play a role in the learning process and warrant further study.
Subject(s)
Learning Curve , Pneumonectomy/methods , Robotic Surgical Procedures , Thoracoscopy/methods , Aged , Blood Loss, Surgical/statistics & numerical data , Female , Humans , Length of Stay/statistics & numerical data , Linear Models , Male , Operative Time , Postoperative ComplicationsABSTRACT
Although hybridisation between closely related species is common and known to be important in plant evolution, hybridisation at the generic level or above is comparatively rare. We address ancient intergeneric hybridisation in the early-divergent angiosperm family Annonaceae by phylogenetic reconstruction, divergence time estimation and coalescent simulation of the genus Dasymaschalon using a multi-locus approach based on molecular data from five chloroplast (matK, psbA-trnH, ndhF, rbcL, and trnL-F) and five nuclear (ITS, ETS, AP3, PhyA, and PhyC) DNA markers. We demonstrate incongruence among different gene trees: Dasymaschalon is retrieved as monophyletic in the nuclear ribosomal tree (based on ITS and ETS), but is non-monophyletic in the chloroplast and Phy-gene trees (with poor resolution in the AP3 tree), with the majority of species assigned to a strongly supported clade but three species (D. filipes, D. longiflorum and D. tibetense) more closely related to the sister genus Friesodielsia. Three contrasting approaches-a coalescent method based on molecular dating, incongruence pattern comparison, and a multi-accession phylogenetic reconstruction-are used to assess the patterns of this gene tree incongruence and test hypotheses of ancient hybridisation and incomplete lineage sorting. Our results support a late Miocene intergeneric hybridisation between members of the Dasymaschalon and Friesodielsia lineages in continental Asia-west Malesia.
Subject(s)
Annonaceae/genetics , Hybridization, Genetic , Phylogeny , Bayes Theorem , Computer Simulation , Models, Genetic , Phytochrome/geneticsABSTRACT
The Dasymaschalon alliance within the early divergent angiosperm family Annonaceae comprises c. 180 species in four genera (Dasymaschalon, Desmos, Friesodielsia, and Monanthotaxis). The alliance offers an excellent opportunity for investigating perianth evolution and functional adaptations because of the presence of different numbers of petal whorls and contrasting floral chamber morphologies. The absence of the inner petal whorl in Dasymaschalon renders it distinctive in the family: previous studies have suggested that its three outermost stamens might be homologous with the inner petals of the sister genus, Friesodielsia, reflecting a homeotic shift of floral organ identify from inner petals to stamens. To investigate this hypothesis and general perianth evolution in the alliance, we (i) compared the floral vascularization of selected Dasymaschalon and Friesodielsia species using paraffin serial sectioning, and (ii) mapped selected perianth characters of inferred functional significance onto a molecular phylogenetic framework of the Dasymaschalon alliance (46 accessions; five cpDNA, and two nrDNA markers). The results indicate that the vasculature of the outermost stamen whorl of Dasymaschalon does not fuse with the perianth cortical vascular system, but instead splits from the basal traces of the free stamen bundles, contradicting previous inferences of homology with the inner corolla whorl of other Annonaceae. The loss of the inner petal whorl in Dasymaschalon is less likely to be due to a homeotic mutation, and instead possibly involved either the loss of genes that are responsible for determining inner petals or else the expression failure of these genes. Optimizations of perianth characters indicate that the absence of the inner petal whorl and the connivence of outer petals during anthesis are synapomorphic for Dasymaschalon. Circadian trapping of pollinators is inferred either to be derived in the stem lineage of the Dasymaschalon-Friesodielsia clade, or else to have evolved in parallel in the Dasymaschalon and Friesodielsia lineages. Subsequent changes in the remaining petals of Dasymaschalon flowers (which do not fully separate during anthesis) are likely to have enabled perpetuation of the circadian trapping mechanism, lessening the adverse impacts of inner petal loss.
ABSTRACT
BACKGROUND: Robotic-assisted thoracoscopic surgery (RobATS) lobectomy is becoming more common for the treatment of lung cancer. As with any relatively new technology, there is the assumption that greater experience leads to greater proficiency. The objective of this study was to analyze outcomes of patients undergoing RobATS lobectomy as hospitals gain experience, and to describe outcomes after conversion to open procedures. STUDY DESIGN: The National Cancer Database (NCDB) was used to analyze robotic lobectomies for lung cancer from 2010 to 2014. Individual hospitals were categorized by the year they began reporting robotic lobectomies to the NCDB. Primary outcomes were perioperative morbidity and mortality and rate of conversion to open lobectomy. RESULTS: There were 7,645 robotic lobectomies identified from 465 hospitals. The overall conversion rate was 9.2% (n = 702). A propensity-matched analysis showed no significant difference between experienced and inexperienced hospitals with respect to 30-day mortality (1.07% vs 2.03%, p = 0.092) or 90-day mortality (2.35% vs 3.63%, p = 0.104). Conversion to open was a predictor of 30-day mortality (odds ratio [OR] 2.54, CI 1.56 to 4.14) and 90-day mortality (OR 2.68, CI 1.83 to 3.91). Patients who underwent conversion had higher 90-day mortality compared with patients not undergoing conversion, in years of experience: 2 (p = 0.043), 3 (p = 0.002), and 4 (p = 0.003). CONCLUSIONS: Mortality after RobATS lobectomy at experienced hospitals is not significantly different than at inexperienced hospitals. Though conversion rates decrease with experience, patients who undergo conversion have higher mortality than those who do not, particularly in hospitals with more experience. This suggests that a deliberate effort to increase experience with and improve patient selection for RobATS lobectomies may ameliorate the conversions and their attendant sequelae.
Subject(s)
Lung Neoplasms/surgery , Pneumonectomy/methods , Robotic Surgical Procedures , Aged , Databases, Factual , Female , Humans , Lung Neoplasms/mortality , Male , Middle Aged , Pneumonectomy/mortality , Propensity Score , Robotic Surgical Procedures/mortality , Thoracic Surgery, Video-Assisted/methods , Treatment Outcome , United StatesABSTRACT
BACKGROUND: Few studies have examined the risk factors for and timing of venous thromboembolism (VTE) in patients undergoing surgical procedures for lung cancer, and there are limited data to formulate guidelines for extended VTE prophylaxis after hospital discharge. This study sought to identify risk factors for postdischarge VTE after lung resection. METHODS: Patients undergoing anatomic resection for lung cancer were identified in the National Surgical Quality Improvement Program database from 2005 to 2015. Patients' demographic and clinical characteristics were evaluated for any association with postdischarge VTE. Predictors of postdischarge VTE were identified using multivariable analysis. RESULTS: VTE occurred in 1.6% (234) of the 14,308 patients identified; 44% (102) VTE events occurred after hospital discharge. Undergoing pneumonectomy was associated with a threefold increased risk for postdischarge VTE compared with lobectomy (2.0% versus 0.6%, p < 0.01), as was open resection compared with minimally invasive resection (0.8% versus 0.6%, p < 0.01). Prolonged operative time (>75th percentile) was also associated with an increased risk for postdischarge VTE compared with shorter operative time. Multivariable analysis identified older age, obesity, pneumonectomy, and prolonged operative time as independent predictors of postdischarge VTE. CONCLUSIONS: Significant proportions of VTE events occur after hospital discharge. Although there are data to suggest that the risk for VTE extends beyond this period, few patients are managed with postdischarge prophylaxis. These data suggest that postdischarge prophylaxis should be considered for those patients at high risk for VTE, particularly for older patients, those who are obese, and after extended or lengthy resections.
Subject(s)
Lung Neoplasms/surgery , Pneumonectomy/adverse effects , Postoperative Complications/etiology , Venous Thromboembolism/etiology , Aged , Aged, 80 and over , Databases, Factual , Female , Humans , Male , Middle Aged , Operative Time , Patient Discharge , Quality Improvement , Retrospective Studies , Risk Factors , Time Factors , United StatesABSTRACT
The pursuit of dedicated research time during surgical residency prolongs training and delays entry into practice. Currently, there is a lack of research quantifying the financial implication of this delay and trainees' understanding of its impact on career earnings. An opportunity cost analysis was performed regarding the impact of delay due to training within general surgery and selected subspecialties. An anonymous survey was distributed to general surgery categorical junior trainees in 2017 at a large academic hospital in the Northeast to determine understanding and beliefs regarding dedicated training on career earnings. For all specialties analyzed, dedicated research time was shown to negatively affect career earnings. The net cost was highest among those intending to pursue cardiothoracic surgery and lowest for those intending to pursue surgical oncology. A total of 26 of 35 (74%) present research residents and clinical residents intending to perform dedicated research time responded to an anonymous survey. On average, survey respondents underestimated the impact of dedicated research time on career earnings by $1.4 million. Dedicated research time during general surgery residency carries a substantial opportunity cost to overall career earnings. General surgery residents lack understanding of both the direction and the magnitude of this opportunity cost.
Subject(s)
Biomedical Research/economics , Career Choice , Education, Medical, Graduate/economics , Specialties, Surgical/economics , Specialties, Surgical/education , Academic Medical Centers , Biomedical Research/education , Cost-Benefit Analysis , Cross-Sectional Studies , Education, Medical, Graduate/methods , Female , General Surgery/economics , General Surgery/education , Humans , Income , Internship and Residency/economics , Male , Quality Control , Time Factors , United StatesABSTRACT
BACKGROUND: Previous literature suggests that patients with non-small cell lung cancer (NSCLC) and unsuspected N2 disease (cN0, pN2) represent a distinct subgroup associated with improved overall survival compared to patients with N2 disease identified prior to resection (cN2, pN2). METHODS: Retrospective analysis of the National Cancer Database of patients from 2004 to 2011 with cN0 and cN2 status found to be pathologic stage III-N2 NSCLC after surgical resection. Comparison of 5-year survival of patients with unsuspected N2 disease versus those with known N2 disease after surgical resection using Kaplan-Meier analysis was made. The independent effect of unsuspected N2 disease on mortality was analyzed using multivariate analysis. RESULTS: A total of 3271 patients with pathologic stage III-N2 NSCLC underwent curative intent surgical resection with or without adjuvant chemotherapy or chemotherapy and radiation. Unsuspected N2 disease was identified in 48% of patients. Patients with unsuspected N2 disease were more likely to have T1 tumors (37 vs. 32%, p < 0.001). Unsuspected N2 disease did not impact 5-year overall survival compared with known N2 when adjuvant therapy was utilized (40 vs. 37%, p = 0.167). Multivariate analysis identified older age, higher comorbidity score, and treatment with surgery alone as independent risk factors for mortality. The presence of unsuspected N2 disease was not significant in this model. CONCLUSIONS: The findings of this study suggest that unsuspected N2 disease is associated with equivalent 5-year survival compared to cN2 disease when adjuvant therapy is employed. These results support the use of adjuvant chemotherapy and radiation therapy when confronted with unsuspected N2 disease after surgical resection for stage IIIA-NSCLC.
Subject(s)
Carcinoma, Non-Small-Cell Lung/mortality , Carcinoma, Non-Small-Cell Lung/pathology , Lung Neoplasms/mortality , Lung Neoplasms/pathology , Aged , Carcinoma, Non-Small-Cell Lung/surgery , Carcinoma, Non-Small-Cell Lung/therapy , Chemotherapy, Adjuvant , Female , Humans , Kaplan-Meier Estimate , Lung Neoplasms/surgery , Lung Neoplasms/therapy , Male , Middle Aged , Neoplasm Staging , Pneumonectomy/methods , Radiotherapy, Adjuvant , Retrospective Studies , Risk Factors , Treatment OutcomeABSTRACT
The Annonaceae, the largest family in the early-divergent order Magnoliales, comprises 107 genera and c. 2,400 species. Previous molecular phylogenetic studies targeting different taxa have generated large quantities of partially overlapping DNA sequence data for many species, although a large-scale phylogeny based on the maximum number of representatives has never been reconstructed. We use a supermatrix of eight chloroplast markers (rbcL, matK, ndhF, psbA-trnH, trnL-F, atpB-rbcL, trnS-G and ycf1) to reconstruct the most comprehensive tree to date, including 705 species (29%) from 105 genera (98%). This provides novel insights into the relationships of five enigmatic genera (Bocagea, Boutiquea, Cardiopetalum, Duckeanthus and Phoenicanthus). Fifteen main clades are retrieved in subfamilies Annonoideae and Malmeoideae collectively, 14 of which correspond with currently recognised tribes. Phoenicanthus cannot be accommodated in any existing tribe, however: it is retrieved as sister to a clade comprising the tribes Dendrokingstonieae, Monocarpieae and Miliuseae, and we therefore validate a new tribe, Phoenicantheae. Our results provide strong support for many previously recognised groups, but also indicate non-monophyly of several genera (Desmopsis, Friesodielsia, Klarobelia, Oxandra, Piptostigma and Stenanona). The relationships of these non-monophyletic genera-and two other genera (Froesiodendron and Melodorum) not yet sampled-are discussed, with recommendations for future research.
Subject(s)
Annonaceae/classification , Annonaceae/genetics , Phylogeny , Bayes Theorem , DNA, Chloroplast , DNA, Plant , Genetic MarkersABSTRACT
BACKGROUND: The Asimina-Disepalum clade (Annonaceae subfam. Annonoideae tribe Annoneae) includes a major Neotropical-Asian biogeographical disjunction. We evaluate whether this disjunction can be explained by the Eocene boreotropics hypothesis, which relies on the existence of extensive boreotropical forests during the Late Palaeocene-Early Eocene thermal maximum (52-50 Ma), followed by disruption of boreotropical vegetation during post-Eocene cooling. Molecular dating using an uncorrelated relaxed molecular clock (UCLD) model with two fossil calibrations, ancestral range estimation, and ecological niche modelling across evolutionary time were performed. Our focus was the geographical origin of Disepalum and general biogeographic patterns within this genus. Comparison of ecological tolerance among extant species and niche reconstructions at ancestral nodes within the clade enabled insights in likely migration routes of lineages, as well as evaluating the role of bioclimatic ecological differentiation in the diversification of Disepalum within Southeast Asia. RESULTS: The inferred vicariance event associated with the Asimina-Disepalum disjunction is estimated to have originated ca. 40 Mya [95% highest posterior density (HPD): 44.3-35.5 Mya]. The Disepalum crown lineage is estimated to have originated ca. 9 Mya (95% HPD: 10.6-7.6), either in western Malesia and continental Southeast Asia, or exclusively in western Malesia. Ecological niche modelling shows that seasonality of temperature and precipitation are major contributors determining the geographical range of species. Ancestral niche modelling furthermore indicates that the ancestor of the Asimina-Disepalum clade likely had bioclimatic preferences close to conditions found in current tropical and subtropical climates across Asia, whereas the ancestors of the Asimina and Disepalum crown groups are projected onto the more subtropical and tropical regions, respectively. CONCLUSIONS: The vicariance event associated with the Neotropical-Asian disjunction within the Asimina-Disepalum clade likely coincided with climatic deterioration at the Eocene-Oligocene boundary. Although detrended component analyses (DCA) indicate that altitude and seasonality of temperature and precipitation have the greatest influence in determining the geographical range of species, isolation due to palaeogeographic and palaeoclimatic events appears to be of greater significance than climate niche differentiation in driving diversification in Disepalum.
Subject(s)
Asimina/classification , Ecosystem , Models, Biological , Phylogeography , Tropical Climate , Asia , Bayes Theorem , Phylogeny , Time FactorsABSTRACT
Several evolutionary lineages in the early divergent angiosperm family Annonaceae possess flowers with a distinctive pollinator trapping mechanism, in which floral phenological events are very precisely timed in relation with pollinator activity patterns. This contrasts with previously described angiosperm pollinator traps, which predominantly function as pitfall traps. We assess the circadian rhythms of pollinators independently of their interactions with flowers, and correlate these data with detailed assessments of floral phenology. We reveal a close temporal alignment between patterns of pollinator activity and the floral phenology driving the trapping mechanism (termed 'circadian trapping' here). Non-trapping species with anthesis of standard duration (c. 48 h) cannot be pollinated effectively by pollinators with a morning-unimodal activity pattern; non-trapping species with abbreviated anthesis (23-27 h) face limitations in utilizing pollinators with a bimodal circadian activity; whereas species that trap pollinators (all with short anthesis) can utilize a broader range of potential pollinators, including those with both unimodal and bimodal circadian rhythms. In addition to broadening the range of potential pollinators based on their activity patterns, circadian trapping endows other selective advantages, including the possibility of an extended staminate phase to promote pollen deposition, and enhanced interfloral movement of pollinators. The relevance of the alignment of floral phenological changes with peaks in pollinator activity is furthermore evaluated for pitfall trap pollination systems.