The commonness of rarity: Global and future distribution of rarity across land plants

A key feature of life's diversity is that some species are common but many more are rare. Nonetheless, at global scales, we do not know what fraction of biodiversity consists of rare species. Here, we present the largest compilation of global plant diversity to quantify the fraction of Earth's plant biodiversity that are rare. A large fraction, ~36.5% of Earth's ~435,000 plant species, are exceedingly rare. Sampling biases and prominent models, such as neutral theory and the k-niche model, cannot account for the observed prevalence of rarity. Our results indicate that (i) climatically more stable regions have harbored rare species and hence a large fraction of Earth's plant species via reduced extinction risk but that (ii) climate change and human land use are now disproportionately impacting rare species. Estimates of global species abundance distributions have important implications for risk assessments and conservation planning in this era of rapid global change.

Species Distribution Modelling: Contrasting presence-only models with plot abundance data

Species distribution models (SDMs) are widely used in ecology and conservation. Presence-only SDMs such as MaxEnt frequently use natural history collections (NHCs) as occurrence data, given their huge numbers and accessibility. NHCs are often spatially biased which may generate inaccuracies in SDMs. Here, we test how the distribution of NHCs and MaxEnt predictions relates to a spatial abundance model, based on a large plot dataset for Amazonian tree species, using inverse distance weighting (IDW). We also propose a new pipeline to deal with inconsistencies in NHCs and to limit the area of occupancy of the species. We found a significant but weak positive relationship between the distribution of NHCs and IDW for 66% of the species. The relationship between SDMs and IDW was also significant but weakly positive for 95% of the species, and sensitivity for both analyses was high. Furthermore, the pipeline removed half of the NHCs records. Presence-only SDM applications should consider this limitation, especially for large biodiversity assessments projects, when they are automatically generated without subsequent checking. Our pipeline provides a conservative estimate of a species’ area of occupancy, within an area slightly larger than its extent of occurrence, compatible to e.g. IUCN red list assessments.

The discovery of the Amazonian tree flora with an updated checklist of all known tree taxa

Amazonia is the most biodiverse rainforest on Earth, and the debate over how many tree species grow there remains contentious. Here we provide a checklist of all tree species collected to date, and describe spatial and temporal trends in data accumulation. We report 530,025 unique collections of trees in Amazonia, dating between 1707 and 2015, for a total of 11,676 species in 1225 genera and 140 families. These figures support recent estimates of 16,000 total Amazonian tree species based on ecological plot data from the Amazonian Tree Diversity Network. Botanical collection in Amazonia is characterized by three major peaks, centred around 1840, 1920, and 1980, which are associated with flora projects and the establishment of inventory plots. Most collections were made in the 20th century. The number of collections has increased exponentially, but shows a slowdown in the last two decades. We find that a species' range size is a better predictor of the number of times it has been collected than the species' estimated basin-wide population size. Finding, describing, and documenting the distribution of the remaining species will require coordinated efforts at under-collected sites.

Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict that most of the world's >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century.

Hyperdominance in the Amazonian tree flora

The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.

Patient discomfort in bitewing examination with film and four digital receptors

The aim was to compare patient discomfort during bitewing examination using five intra-oral receptors: a conventional film, a storage phosphor plate with a new soft cover, an already manufactured and sold sensor with a wire and two square and two rounded corners, a new version of a previously developed sensor with a wire and four square corners, and a newly developed sensor with a wire and four rounded corners. 60 patients participated in the study. The five receptors [a Kodak paper pack film (Eastman Kodak Company, Rochester, NY), a DIGORA® Optime phosphor plate (Soredex, Tuusula, Finland), and SuniRay (Suni Medical Imaging, Inc., San Jose, CA), DIGORA Toto (Soredex) and Snapshot (Instrumentarium Dental, Tuusula, Finland) complementary metal-oxide-semiconductors] with differences in ergonomic shape were placed in the mouth for a bitewing examination for approximately 10 s. The patients rated their discomfort on a 100 mm visual analogue scale after having had each receptor positioned. There was no significant difference in patient discomfort score between the conventional film and the Snapshot sensor (p > 0.05). Both conventional film and Snapshot were significantly less uncomfortable than the other receptors (p < 0.05). No significant difference was seen between the storage phosphor plate and the SuniRay sensor (p > 0.05). The storage phosphor plate was significantly less uncomfortable than the DIGORA Toto sensor (p < 0.05). There was no significant difference in the perception of discomfort between the conventional film and an ergonomically shaped wired sensor with rounded corners.

Control for recurrences of urinary bladder tumours by transabdominal ultrasonic scanning

By transabdominal ultrasonic scanning of the filled bladder it is possible to examine the surface of the bladder urothelium in the outpatient clinic. In a "blind" study of 129 patients controlled for recurrences of urinary bladder tumours the results of dynamic transabdominal ultrasonography were compared with the results of cystoscopy. The ultrasound could identify the recurrences of 5 mm or above in size significantly. Below 5 mm in dimension, when positioned in the dome of the bladder or at severe trabeculation the ultrasonic scanning lead to a misdiagnosis. No invasive recurrences were overlooked by ultrasonography. We will advocate that transabdominal ultrasonic scanning replace routine cystoscopy in low-risk patients with superficial bladder tumours of the Ta category and a low grade after the primary transurethral treatment and no or few recurrences of the same Ta category at the first control cystoscopy. On the other hand we will recommend to continue cystoscopy of patients with frequently recurring urinary bladder tumours, the high grade Ta tumours, carcinoma in situ because of the risk of invasive growth, and patients with primary invasive tumours including those with the superficial invasion (category T1).