Tropical America Research Articles

Niche-dependent forest and savanna fragmentation in Tropical South America during the Last Glacial Maximum

The refugia hypothesis, often used to explain Amazonia’s high biodiversity, initially received ample support but has garnered increasing criticism over time. Palynological, phylogenetic, and vegetation model reconstruction studies have been invoked to support the opposing arguments of extensive fragmentation versus a stable Amazonian Forest during Pleistocene glacial maxima. Here, we test the past existence of forest fragments and savanna connectivity by bias-correcting vegetation distributions from a Dynamic Vegetation Model (DVM) driven by paleoclimate simulations for South America during the Last Glacial Maximum (LGM). We find evidence for fragmented forests akin to refugia with extensive tropical humid forests to the west and forest islands in central/southern Amazonia. Drier ecosystems of Northern Llanos, Caatinga and Cerrado may have merged into continuous savanna/grasslands that dominated the continent. However, our reconstructions suggest taller, dense woodland/tropical savanna vegetation and areas of similar bioclimate connected disparate forest fragments across Amazonia. This ecotonal biome may have acted as a corridor for generalist forest and savanna species, creating connectivity that allows for range expansion during glacial periods. Simultaneously, it could have served as a barrier for specialists, inducing diversification through the formation of ‘semi-refugia’.

Pacific Interannual and Multidecadal Variability Recorded in δ18O of South American Summer Monsoon Precipitation

AbstractThe South American summer monsoon (SASM) generates important hydroclimatic impacts in (sub‐)tropical South America and isotopic tracers recorded in paleoclimatic archives allow for assessing its long‐term response to Pacific variability prior to modern observations. Stable oxygen isotopes in precipitation integrate hydroclimatic changes during the SASM mature phase from December to February (DJF) in response to the Interdecadal Pacific Oscillation (IPO) and El Niño—Southern Oscillation (ENSO), respectively. Here, results from the isotope‐enabled Community Atmosphere Model v.5 are compared with highly resolved and precisely dated isotopic records from speleothems, tree rings, lake and ice cores during the industrial era (1880–2000 CE) and validated against observations from the International Atomic Energy Agency (IAEA) network. Pacific sea surface temperatures (SSTs) are coupled to the isotopic composition of SASM precipitation through perturbations in the Walker circulation associated with low‐ (IPO) and high‐frequency (ENSO) variability, impacting convective activity over tropical South America and the tropical Atlantic. Changes in convection over this monsoon entrance region ultimately control the downstream oxygen isotopic composition of precipitation recorded in paleoclimate archives. Overall, model results, paleoclimate records and IAEA data agree on the isotopic response to Pacific SST forcing. These results highlight the potential for long isotopic paleoclimate records to reconstruct Pacific climate variability on both high‐ and low‐frequency timescales. Furthermore, the isolation of the IPO signal in a diverse set of isotopic archives invites the reinterpretation of other paleoclimate proxies for identifying this historically overlooked forcing.

Comprehensive Husbandry Protocol for Corydoras Catfish and Many Other Amazonian Species.

A variety of fish species have proven instrumental in the investigation of evolution, behavior, ecology, and physiology, among many other fields. Many model systems (e.g., zebrafish, guppies, and three-spined sticklebacks) have been maintained by institutions and have had protocols written with respect to their husbandry. Here we present the protocols we have developed to maintain and breed a variety of Corydoras catfish species, which are native to the tropical Americas. Corydoras species are excellent systems for investigating behavior, ecology, and other topics, and our husbandry protocols would be suitable for nearly every species in the genus. In addition, these protocols are appropriate for a variety of softwater Amazonian species, and we present options for a variety of housing and husbandry conditions. On the whole, we suggest that, in a scientific laboratory setting, the use of remineralized reverse osmosis water is most appropriate and that in context, a single measure, total dissolved solids, can be used to monitor the water chemistry for water introduced to fish enclosures.

A multiproxy approach for the feeding ecology of Late Miocene ground sloths from the southwestern Amazonia, Upper Solimões Formation, Brazil

A rich assemblage of fossil sloths is recognized in the southwestern Brazilian Amazon, Upper Solimões Formation (Acre Basin), and represents some of the most diverse Folivora fauna from the Late Miocene of tropical South America. Here, we have used a multiproxy approach using carbon (δ13Csc) and oxygen (δ18Osc) isotope compositions of bioapatite structural carbonate, stereomicrowear, ecomorphological indices (relative muzzle width, RMW and occlusal surface area, OSA), and body mass estimates in order to suggest the habitats and diet of the mylodontids (Octodontobradys puruensis, Urumacotherium campbelli, Pseudoprepotherium venezuelanum and Mylodontinae gen. et. sp. nov.) and the nothrotheriid (cf. Mionothropus) ground sloths from localities along the banks at the Purus and Acre rivers in Amazonas and Acre states. The isotopic results (δ13Csc = −13.2 ± 1.2 ‰; δ18Osc = +24.7 ± 0.8 ‰) indicated a consistently C3 plant diet in open-canopy woodland and closed-canopy forest habitats during warm conditions across the Tortonian ages (∼10 and 8.5 Myr). U. campbelli (Urumacotherium sp., bm: 605 kg; Niterói Site) and cf. Mionothropus (bm: 163 kg; Acre 5 Site) possibly had specialized browsing habits (folivorous/frugivorous), due to the few coarse scars in relatively polished tooth surfaces and elongate skull with narrow muzzle, respectively. Both taxa, as also P. venezuelanum (bm: 733 kg; Niterói Site), showed a low OSA values suggesting limited oral food processing offset by higher fermentation capacity and/or lower metabolic requirements. Efficient capacity for oral food processing and a generalized browsing habit with consumption of high intrinsic toughness and abrasiveness items were inferred for O. puruensis (bm: 526 kg; Talismã Site), resembling the pattern observed for the Pleistocene megathere Eremotherium laurillardi from the southwestern Amazon (Acre State). A non-selective browser diet was also supported for the Mylodontinae gen. et. sp. nov. specimen from Cavalcante Site; its similar dentary morphology to the bulk-feeder taxa implies that this individual could occasionally eat C3 herbaceous/grasses.

Global, regional, and national drowning trends from 1990 to 2021: Results from the 2021 Global Burden of Disease Study.

Drowning is a preventable public health concern that burdens emergency care systems globally. This study comprehensively evaluated fatal drowning patterns across population, time, and geography from 1990 to 2021 to inform effective prevention strategies. Using the 2021 Global Burden of Disease Study framework and standardized estimation methods, the study analyzed global and regional drowning burden in terms of mortality, incidence, and disability-adjusted life-years (DALYs), based on population registry data and drowning-related epidemiological covariates. Global drowning incidents decreased by 33.67% from 1990 to 2021. The drowning incidence rate and mortality rate declined from 24.20 and 9.68 per 100,000 in 1990 to 10.85 and 3.48 per 100,000 in 2021, respectively. Years of life lost and DALYs rates due to drowning also decreased significantly, from 715.80 and 718.69 per 100,000 in 1990 to 197.64 and 198.92 per 100,000 in 2021. Regionally, East Asia had the highest drowning mortality (27.15% of global deaths), while the high-income Asia Pacific region experienced the highest incidence rate (21.38 per 100,000). South Asia had the greatest number of drowning deaths (75,639). Tropical Latin America showed the largest incidence decline, while high-income Asia Pacific exhibited increasing trends. Drowning disproportionately affected children under 5 and the elderly in most regions. While global drowning rates have declined, progress varies across regions. To improve prevention, focus should target low-income/middle-income countries and vulnerable populations like children and the elderly. Increased investment in safety education and rescue resources is vital to address their disproportionate risks.

The global incidence and trends of three common flavivirus infections (Dengue, yellow fever, and Zika) from 2011 to 2021.

Flavivirus pose a continued threat to global health, yet their worldwide burden and trends remain poorly quantified. We aimed to evaluate the global, regional, and national incidence of three common flavivirus infections (Dengue, yellow fever, and Zika) from 2011 to 2021. Data on the number and rate of incidence for the three common flavivirus infection in 204 countries and territories were retrieved from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021. The estimated annual percent change (EAPC) was calculated to quantify the temporal trend during 2011-2016, 2016-2019, and 2019-2021, respectively. In 2021, an estimated 59,220,428 individuals were infected globally, comprising 58,964,185 cases of dengue, 86,509 cases of yellow fever, and 169,734 cases of Zika virus infection. The age-standardized incidence rate (ASIR) of the three common flavivirus infections increased by an annual average of 5.08% (95% CI 4.12 to 6.05) globally from 2011 to 2016, whereas decreased by an annual average of -8.37% (95% CI -12.46 to -4.08) per year between 2016 to 2019. The ASIR remained stable during 2019-2021, with an average change of 0.69% (95% CI -0.96 to 2.37) per year globally for the three common flavivirus infections. Regionally, the burden of the three common flavivirus infections was primarily concentrated in those regions with middle income, such as South Asia, Southeast Asia, and Tropical Latin America. Additionally, at the country level, there was an inverted "U" relationship between the SDI level and the ASI. Notably, an increase in the average age of infected cases has been observed worldwide, particularly in higher-income regions. Flavivirus infections are an expanding public health concern worldwide, with considerable regional and demographic variation in the incidence. Policymakers and healthcare providers must stay vigilant regarding the impact of COVID-19 and other environmental factors on the risk of flavivirus infection and be prepared for potential future outbreaks.

A new data-driven map predicts substantial undocumented peatland areas in Amazonia

Abstract Tropical peatlands are among the most carbon-dense terrestrial ecosystems yet recorded. Collectively, they comprise a large but highly uncertain reservoir of the global carbon cycle, with wide-ranging estimates of their global area (441 025–1700 000 km2) and below-ground carbon storage (105–288 Pg C). Substantial gaps remain in our understanding of peatland distribution in some key regions, including most of tropical South America. Here we compile 2413 ground reference points in and around Amazonian peatlands and use them alongside a stack of remote sensing products in a random forest model to generate the first field-data-driven model of peatland distribution across the Amazon basin. Our model predicts a total Amazonian peatland extent of 251 015 km2 (95th percentile confidence interval: 128 671–373 359), greater than that of the Congo basin, but around 30% smaller than a recent model-derived estimate of peatland area across Amazonia. The model performs relatively well against point observations but spatial gaps in the ground reference dataset mean that model uncertainty remains high, particularly in parts of Brazil and Bolivia. For example, we predict significant peatland areas in northern Peru with relatively high confidence, while peatland areas in the Rio Negro basin and adjacent south-western Orinoco basin which have previously been predicted to hold Campinarana or white sand forests, are predicted with greater uncertainty. Similarly, we predict large areas of peatlands in Bolivia, surprisingly given the strong climatic seasonality found over most of the country. Very little field data exists with which to quantitatively assess the accuracy of our map in these regions. Data gaps such as these should be a high priority for new field sampling. This new map can facilitate future research into the vulnerability of peatlands to climate change and anthropogenic impacts, which is likely to vary spatially across the Amazon basin.

Host Preference and Developmental Dynamics of Fall Armyworm <i>Spodoptera frugiperda</i> (J E Smith)

The invasive fall army worm Spodoptera frugiperda (J E Smith) is a major global agricultural pest, originally from tropical and subtropical America, now affecting over 80 plant species across Africa, Asia, and beyond. This study examines its host preferences and developmental dynamics, focusing on four host plants: Zea mays L., Glycine max L., Carica papaya L., and Brassica oleraceae var. acephala L. Using a complete randomized design, mortality and developmental rates of larvae were evaluated. These results revealed that C. papaya and B. oleraceae leaves resulted in maximum larval mortality (80 and 65%, respectively). This can be attributed to the presence of secondary metabolites like tannins, terpenoids, flavonoids, and alkaloids, which exhibit toxic and antifeedant properties. This study highlights the armyworm's ability to adapt to alternative hosts like G. max and B. oleraceae, even surviving on C. papaya leaves, typically used as a botanical pesticide.

Isolation, genome analysis and tissue localization of Ceratobasidium theobromae, a new encounter pathogen of cassava in Southeast Asia

In Southeast Asia (SEA) fastidious fungi of the Ceratobasidium genus are associated with proliferation of sprouts and vascular necrosis in cacao and cassava, crops that were introduced from the tropical Americas to this region. Here, we report the isolation and in vitro culture of a Ceratobasidium sp. isolated from cassava with symptoms of witches’ broom disease (CWBD), a devastating disease of this crop in SEA. The genome characterization using a hybrid assembly strategy identifies the fungus as an isolate of the species C. theobromae, the causal agent of vascular streak dieback of cacao in SEA. Both fungi have a genome size > 31 Mb (G+C content 49%), share > 98% nucleotide identity of the Internal Transcribed Spacer (ITS) and > 94% in genes used for species-level identification. Using RNAscope® we traced the pathogen and confirmed its irregular distribution in the xylem and epidermis along the cassava stem, which explains the obtention of healthy planting material from symptom-free parts of a diseased plant. These results are essential for understanding the epidemiology of CWBD, as a basis for disease management including measures to prevent further spread and minimize the risk of introducing C. theobromae via long-distance movement of cassava materials to Africa and the Americas.

Annual temperature, body size, and sexual size dimorphism in the evolution of Pyrgomorphidae.

In many animal species, larger body size is positively correlated with male mating success and female fecundity. However, in the case of insects, in high seasonality environments, natural selection favors a faster maturation that decreases the risk of pre-reproductive death. However, this advantageous adaptation comes at a tradeoff, resulting in a reduction in body size. Maturation time is influenced by environmental factors, such as temperature, season length, and food availability during the rains. The geographic variation in these parameters provides an opportunity to study their impact on the adaptive evolution of body size in Pyrgomorphidae grasshoppers. These grasshoppers exhibit remarkable variation in body size and wing development and can be found in diverse plant communities across Africa, Asia, Australia, and tropical America. In this study, we utilized a phylogenetic approach to examine the evolution of body size, considering climatic factors, and the influence of sexual selection on size differences between males and females. We found a positive correlation between mean annual temperature and sexual size dimorphism (SSD). Remarkably, species exhibiting a strong bias toward larger females were found to be adapted to regions with higher temperatures. In the Pyrgomorphidae family, an intermediate body size was identified as the ancestral trait. Additionally, winged male and female grasshoppers were observed to be larger than their wingless counterparts. Despite the potential conflicting pressures on body size in males and females, these grasshoppers adhere to Rench's Rule, suggesting that sexual selection on males' body size may explain the evolution of SSD.

Enhanced Carbon Flux Response to Atmospheric Aridity and Water Storage Deficit During the 2015–2016 El Niño Compromised Carbon Balance Recovery in Tropical South America

AbstractDuring the 2015–2016 El Niño, the Amazon basin released almost one gigaton of carbon (GtC) into the atmosphere due to extreme temperatures and drought. The link between the drought impact and recovery of the total carbon pools and its biogeochemical drivers is still unknown. With satellite‐constrained net carbon exchange and its component fluxes including gross primary production and fire emissions, we show that the total carbon loss caused by the 2015–2016 El Niño had not recovered by the end of 2018. Forest ecosystems over the Northeastern (NE) Amazon suffered a cumulative total carbon loss of ∼0.6 GtC through December 2018, driven primarily by a suppression of photosynthesis whereas southeastern savannah carbon loss was driven in part by fire. We attribute the slow recovery to the unexpected large carbon loss caused by the severe atmospheric aridity coupled with a water storage deficit during drought. We show the attenuation of carbon uptake is three times higher than expected from the pre‐drought sensitivity to atmospheric aridity and ground water supply. Our study fills an important knowledge gap in our understanding of the unexpectedly enhanced response of carbon fluxes to atmospheric aridity and water storage deficit and its impact on regional post‐drought recovery as a function of the vegetation types and climate perturbations. Our results suggest that the disproportionate impact of water supply and demand could compromise resiliency of the Amazonian carbon balance to future increases in extreme events.

Trends in the burden of female infertility among adults aged 20–49 years during 1990–2019: an analysis of data from the Global Burden of Disease Study 2019

ObjectivesThe aim of this analysis was to investigate the worldwide distribution and trends in the burden of female infertility (FI).Design and settingAnalysis of cross-sectional data from 1990 to 2019 from...

Distribution Patterns and Environmental Determinants of Invasive Alien Plants on Subtropical Islands (Fujian, China)

Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the composition and origin of invasive alien plants on 77 islands in Fujian. The similarity in the distribution of invasive alien plants between islands was assessed using the UPGMA. Moreover, feature selection, best-subset regression, and variance decomposition were performed using 19 environmental variables characterizing climate, anthropogenic disturbance, and landscape/geography, as well as the species richness and growth forms of invasive alien plants. Through the analysis, the main environmental factors affecting the species richness and growth forms of invasive alien plants on the Fujian islands were identified. The results showed 142 species of invasive alien plants in 38 families and 102 genera on 77 islands in Fujian. Annual herbs constituted the most representative growth form of invasive alien plants and tropical America was the main origin of invasive alien plants. The distribution of invasive alien plants across the 77 islands in Fujian showed a high degree of similarity, suggesting a nested pattern in their distribution. The proportions of building and farmland area (BFA), island area (A), and maximum elevation (ME) were the main driving factors of species richness and growth forms for invasive alien plants. In particular, BFA played a key role in driving plant invasion. The results of this study can help establish an early warning mechanism for invasive alien plants and better implement island ecological management, which are important for the protection of subtropical island ecosystems.

Identification of entomopathogenic nematodes in Hainan Province, China and their efficacy against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a notorious migratory pest native to tropical and subtropical America. It invaded China in 2018 and can reproduce annually in Hainan Province. Entomopathogenic nematodes (EPNs) have gained interest as potential bioagent due to as an alternative to conventional pesticides are EPNs. We isolated 19 EPNs out of 155 soil samples using the Galleria-baiting method. This was the first comprehensive survey of EPNs in Hainan Province. Phylogenetic analyses of the ITS and D2D3 expansion region of the 28S rDNA gene were performed, and 19 strains belonging to Steinernema aciari, Steinernema sp., Heterorhabditis sp., Oscheius sp., Oscheius myriophilus and O. amsactae were identified. It was shown that S. aciari 22,000 caused 100% and 96% mortality to the third and sixth instar larvae of S. frugiperda, respectively. When the pupae of S. frugiperda were exposed to S. aciari 22,000, the pupae died after emergence. Our study suggests S. aciari 22,000 is a promising indigenous biocontrol agent against S. frugiperda in the future. These findings underscore the importance of continued investigation into the potential of indigenous EPNs for sustainable management strategies of S. frugiperda in agricultural areas.

Evaluation of the Antioxidant and Anti-Inflammatory Activities and Acute Toxicity of Caco Seed (Chrysobalanus icaco L.) in Murine Models.

Chysobalanus icaco L. (C. icaco) is a plant that is native to tropical America and Africa. It is also found in the southeast region of Mexico, where it is used as food and to treat certain diseases. This study aimed to carry out a phytochemical analysis of an aqueous extract of C. icaco seed (AECS), including its total phenol content (TPC), total flavonoid content (TFC), and condensed tannins (CT). It also aimed to examine the antioxidant and metal-ion-reducing potential of the AECS in vitro, as well as its toxicity and anti-inflammatory effect in mice. Antioxidant and metal-ion-reducing potential was examined by inhibiting DPPH, ABTS, and FRAP. The acute toxicity test involved a single administration of different doses of the AECS (0.5, 1, and 2 g/kg body weight). Finally, a single administration at doses of 150, 300, and 600 mg/kg of the AECS was used in the carrageenan-induced model of subplantar acute edema. The results showed that the AECS contained 124.14 ± 0.32 mg GAE, 1.65 ± 0.02 mg EQ, and 0.910 ± 0.01 mg of catechin equivalents/g dried extract (mg EC/g de extract) for TPC, TFC and CT, respectively. In the antioxidant potential assays, the values of the median inhibition concentration (IC50) of the AECS were determined with DPPH (0.050 mg/mL), ABTS (0.074 mg/mL), and FRAP (0.49 mg/mL). Acute toxicity testing of the AECS revealed no lethality, with a median lethal dose (LD50) value of >2 g/kg by the intragastric route. Finally, for inhibition of acute edema, the AECS decreased inflammation by 55%, similar to indomethacin (59%, p > 0.05). These results demonstrated that C. icaco seed could be considered a source of bioactive molecules for therapeutic purposes due to its antioxidant potential and anti-inflammatory activity derived from TPC, with no lethal effect from a single intragastric administration in mice.

An integrative taxonomy of Asian Caryodaphnopsis (Lauraceae) based on morphology and phylogenomics

AbstractCaryodaphnopsis is a small genus of the Lauraceae family with disjunct distribution in tropical Asia and tropical America. Taxa from each region form a well­supported monophyletic clade. However, the species circumscription in Asian Caryodaphnopsis remains ambiguous due to few and generally unstable morphological characters used for classification. To address this, we conducted an integrative taxonomy of the Asian clade. We investigated 13 populations, sampled 57 accessions covering the entire taxonomic diversity, geographic range, and morphological variation in Asia, and reconstructed a new phylogeny using single‐nucleotide polymorphisms. We obtained a well‐resolved phylogeny of the Asian Caryodaphnopsis. The first diverged clade consists of three species endemic to lowland forests. The second (largest) clade (eight species in total) mainly occurs in limestone mountain forests and has a double‐layered lower leaf epidermis morphology of type 2 (less complete roomy with closed “roof”) and type 3 (complete roomy with closed “roof”). Based on the diagnostic morphological characters, distinct distributional ranges, and monophyly of each clade, we recognize 12 species in the Asian Caryodaphnopsis, including three new species: C. cangyuanensis sp. nov., C. hekouensis sp. nov., and C. rubrinervis sp. nov. We also reinstate C. latifolia, and re‐circumscribe the widespread C. tonkinensis and other species based on fruit and inflorescence morphology and molecular evidence.

Hydroclimate variability in the Tropical Andes recorded by δ18O isotopes from a new network of Polylepis tarapacana tree-rings

Stable oxygen isotopes records (δ18O) in tree-rings are commonly used to assess the response of trees to environmental variability being a valuable tool for studying past climate at different temporal and spatial scales. This is particularly relevant in semi-arid regions like the southern Tropical Andes, where ongoing environmental changes coincide with a rapidly increasing demand for hydrological resources, presenting a challenge for ecosystem dynamics and water resource management. In this study, we aim to determine the main spatio-temporal variability of a new network of δ18O Polylepis tarapacana chronologies during the last century, and their relationships with hydroclimate and tropical circulation at local to subcontinental scales throughout the Tropical Andes. For this purpose, we develop six δ18O P. tarapacana tree-ring chronologies across a 450 km latitudinal moisture gradient in the southern Tropical Andes adjacent to the Atacama Desert, covering the period 1900–2007. Results show a clear latitudinal gradient in the δ18O values across the network and significant relationships are observed with other δ18O tree-ring chronologies in Tropical South America, demonstrating clear regional climate influences at a subcontinental scale. A principal component analysis of the δ18O tree-ring chronologies demonstrate a strong regional environmental signal contained in the network, exhibiting a main temporal pattern (PC1 δ18O) that explains 63% of the total variance during the period 1900–2007. Comparisons between PC1 δ18O and environmental variables showed significant negative relationships with precipitation and soil moisture, and positive relationships with temperature and vapor pressure deficit (VPD) during summer when the South American monsoon occurs. The main δ18O tree-ring network signal clearly records tropical atmospheric and circulation patterns across South America. The easterly wind flux conditions from the Amazon basin favor lower δ18O values, and the PC1 δ18O exhibit significant positive correlations with VPD across the entire Tropical Andes and the northern portion of the Amazon basin, and as well as outgoing longwave radiation across the southern Tropical Andes and part of the Amazon basin. The close relationships between the regional signals from our δ18O tree-ring network with the previously mentioned parameters, highlight the potential to develop future hydroclimatic-related reconstructions with these δ18O records to assess climate variability and change across the Tropical Andes.

Transcriptome sequencing data provide a solid base to understand the phylogenetic relationships, biogeography and reticulated evolution of the genus Zamia L. (Cycadales: Zamiaceae).

Cycads are a key lineage to understand the early evolution of seed plants and their response to past environmental changes. However, tracing the evolutionary trajectory of cycad species is challenging when the robust relationships at inter- or infrageneric level are not well resolved. Here, using 2901 single-copy nuclear genes, we explored the species relationships and gene flow within the second largest genus of cycads, i.e. Zamia, based on phylotranscriptomic analyses of 90 % extant Zamia species. Based on a well-resolved phylogenetic framework, we performed gene flow analyses, molecular dating and biogeographical reconstruction to examine the spatiotemporal evolution of Zamia. We also performed ancestral state reconstruction of a total of 62 traits of the genus to comprehensively investigate its morphological evolution. Zamia comprises seven major clades corresponding to seven distinct distribution areas in the Americas, with at least three reticulation nodes revealed in this genus. Extant lineages of Zamia initially diversified around 18.4-32.6 (29.14) million years ago in Mega-Mexico, and then expanded eastward into the Caribbean and southward into Central and South America. Ancestral state reconstruction revealed homoplasy in most of the morphological characters. This study revealed congruent phylogenetic relationships from comparative methods/datasets, with some conflicts being the result of incomplete lineage sorting and ancient/recent hybridization events. The strong association between the clades and the biogeographic areas suggested that ancient dispersal events shaped the modern distribution pattern, and regional climatic factors may have resulted in the following in situ diversification. Climate cooling starting during the mid-Miocene is associated with the global expansion of Zamia to tropical South America that has dramatically driven lineage diversification in the New World flora, as well as the extinction of cycad species in the nowadays cooler regions of both hemispheres, as indicated by the fossil records.

Effect of Foliar Feeding of Plant Growth Regulator and Nutrients on Phenological Attributes of Guava (Psidium guajava L.) cv Apple Colour

Guava, (Psidium guajava L.), small tropical tree or shrub of the family Myrtaceae, cultivated for its edible fruits. Guava trees are native to tropical America and are grown in tropical and subtropical areas worldwide. Nutrients and PGR play a crucial role in flowering and fruit production and their deficiency can significantly impact the yield, productivity, and quality of fruits. Therefore, keeping these points in view, the present investigation was carried out on a 10-year-old guava plant in a high-density plantation (3x3) at the Fruit Research Station Imaliya, Department of Horticulture, J.N.K.V.V., Jabalpur (M.P.) during the mrig-bahar season of 2022-23. The study employed a Factorial Randomised Block Design (FRBD) with 20 treatment combinations involving Plant Growth Regulators (PGR) like salicylic acid and various nutrients, replicated three times. Results indicated that the combination of salicylic acid (200 ppm) + borax (0.5%) significantly influenced several phenological parameters. This treatment resulted in the earliest flower bud initiation (18.33 days) after foliar application, the highest average number of flower buds per shoot (7.05), minimum days to 50% flowering (33.67 days), maximum average number of flowers per shoot (6.95), the highest fruit set percentage (92.18%), the highest fruit retention percentage (81.23%), and the lowest fruit drop percentage (18.77%). The application of salicylic acid at 200 ppm in conjunction with borax at 0.5% (S2 M4) followed by salicylic acid at 300 ppm with borax at 0.5% (S3 M4) demonstrated exceptional efficacy in significantly optimizing phenological parameters when compared to the control.

Taxonomic study on selected species of stingless bees (Hymenoptera: Apidae: Meliponini) in Sulawesi Island, Indonesia

Abstract. Trianto M, Arisuryanti T, Purwanto H, Ubaidillah R. 2024. Taxonomic study on selected species of stingless bees (Hymenoptera: Apidae: Meliponini) in Sulawesi Island, Indonesia. Biodiversitas 25: 2290-2306. Stingless bees are strong candidates as alternative crop pollinators. They are found throughout the tropics, with the exception of the Pacific islands. There are three tropical regions in the world, namely the tropical Americas (Neotropic), Sub-Saharan Africa (Afrotropic), and Indoaustralian (Austroasiatic) region. In this research, we explored the morphological and morphometric characteristics of stingless bees in Sulawesi Island, Indonesia. The genera and species identification of stingless bees were based on morphological characters and coloration, such as the structure and color of the antenna, head, thorax, wing, leg and abdomen. Morphological and morphometric identification of 10 species of stingless bees consisting of five genera, namely the genera Heterotrigona, Homotrigona, Lepidotrigona, Tetragonula, and Wallacetrigona. The genus Tetragonula consists of six small species (<4 mm), namely T. biroi, T. clypearis, T. fuscobalteata, T. laeviceps, T. pagdeni, and T. sapiens. The genera Heterotrigona, Homotrigona, Lepidotrigona, and Wallacetrigona are a group of large stingless bees (>4 mm), each consisting of one species, namely H. itama, H. canifrons, L. terminata, and W. incisa. H. itama and H. canifrons are new records on Sulawesi Island. These species are found in Lore Lindu National Park (TNLL). Until 2023, these species were only found in Java, Kalimantan and Sumatra. This research can be used as a guide in the identification and validation of stingless bee species on Sulawesi Island.