The evolution and diversification of ancient megathermal angiosperm lineages with Africa-India origins in Asian tropical forests is poorly understood because of the lack of reliable fossils. Our ...palaeobiogeographical analysis of pollen fossils from Africa and India combined with molecular data and fossil amber records suggest a tropical-African origin of Dipterocarpaceae during the mid-Cretaceous and its dispersal to India during the Late Maastrichtian and Paleocene, leading to range expansion of aseasonal dipterocarps on the Indian Plate. The India-Asia collision further facilitated the dispersal of dipterocarps from India to similar climatic zones in Southeast Asia, which supports their out-of-India migration. The dispersal pathway suggested for Dipterocarpaceae may provide a framework for an alternative biogeographic hypothesis for several megathermal angiosperm families that are presently widely distributed in Southeast Asia.
Aim
We used an eco‐phylogenetic approach to investigate the diversity and assembly patterns of tropical dry forests (TDFs) in Central India. We aimed at informing conservation and restoration ...practices in these anthropogenically disturbed forests by identifying potential habitats of conservation significance and elements of regional biodiversity most vulnerable to human impact and climate change.
Location
Tropical dry forests of Madhya Pradesh, Central India.
Methods
We analysed the species richness, stem density, basal area and phylogenetic structure (standardized effect size of MNTD, MPD, PD and community evolutionary distinctiveness cED) of 117 tree species assemblages distributed across a ~230 to ~940 m elevational gradient. We examined how these community measures and taxonomic (Sørensen) and phylogenetic (UniFrac) beta diversity varied with elevation, precipitation, temperature and climatic stress.
Results
Species richness, phylogenetic diversity, stem density and basal area were positively correlated with elevation, with high‐elevation plots exhibiting cooler temperatures, higher precipitation and lower stress. High‐elevation assemblages also trended towards greater phylogenetic dispersion, which diminished at lower elevations and in drier, more stressful plots. Phylogenetic turnover was observed across the elevation gradient, and species evolutionary distinctiveness increased at lower elevations and under harsher abiotic conditions.
Main Conclusions
Harsher abiotic conditions at low elevations may act as a selective filter on plant lineages, leading to phylogenetically clustered low‐diversity assemblages. These assemblages contained more evolutionarily distinct species that may contribute disproportionately to biodiversity. Conversely, milder abiotic conditions at high elevations may serve as refuges for drought‐sensitive species, resulting in more diverse assemblages. Conservation practices that prioritize both high‐ and low‐elevation habitats could promote the persistence of evolutionarily distinct species and areas of high biodiversity within the Central Indian landscape. Establishing connectivity between these habitats may provide a range of climatic conditions for species to retreat to or persist within as climates change.
Background & objectives: India has been reporting the cases of coronavirus disease 2019 (COVID-19) since January 30, 2020. The Indian Council of Medical Research (ICMR) formulated and established ...laboratory surveillance for COVID-19. In this study, an analysis of the surveillance data was done to describe the testing performance and descriptive epidemiology of COVID-19 cases by time, place and person.
Methods: The data were extracted from January 22 to April 30, 2020. The frequencies of testing performance were described over time and by place. We described cases by time (epidemic curve by date of specimen collection; seven-day moving average), place (area map) and person (attack rate by age, sex and contact status), and trends were represented along with public health measures and events.
Results: Between January 22 and April 30, 2020, a total of 1,021,518 individuals were tested for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Testing increased from about 250 individuals per day in the beginning of March to 50,000 specimens per day by the end of April 2020. Overall, 40,184 (3.9%) tests were reported positive. The proportion of positive cases was highest among symptomatic and asymptomatic contacts, 2-3-fold higher than among those with severe acute respiratory infection, or those with an international travel history or healthcare workers. The attack rate (per million) by age was highest among those aged 50-69 yr (63.3) and was lowest among those under 10 yr (6.1). The attack rate was higher among males (41.6) than females (24.3). The secondary attack rate was 6.0 per cent. Overall, 99.0 per cent of 736 districts reported testing and 71.1 per cent reported COVID-19 cases.
Interpretation & conclusions: The coverage and frequency of ICMR's laboratory surveillance for SARS-CoV-2 improved over time. COVID-19 was reported from most parts of India, and the attack rate was more among men and the elderly and common among close contacts. Analysis of the data indicates that for further insight, additional surveillance tools and strategies at the national and sub-national levels are needed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF