Directly modelling population dynamics in the South American Arid Diagonal using 14C dates

Large anthropogenic 14C datasets are widely used to generate summed probability distributions (SPDs) as a proxy for past human population levels. However, SPDs are a poor proxy when datasets are small, bearing little relationship to true population dynamics. Instead, more robust inferences can be achieved by directly modelling the population and assessing the model likelihood given the data. We introduce the R package ADMUR which uses a continuous piecewise linear (CPL) model of population change, calculates the model likelihood given a 14C dataset, estimates credible intervals using Markov chain Monte Carlo, applies a goodness-of-fit test, and uses the Schwarz Criterion to compare CPL models. We demonstrate the efficacy of this method using toy data, showing that spurious dynamics are avoided when sample sizes are small, and true population dynamics are recovered as sample sizes increase. Finally, we use an improved 14C dataset for the South American Arid Diagonal to compare CPL modelling to current simulation methods, and identify three Holocene phases when population trajectory estimates changed from rapid initial growth of 4.15% per generation to a decline of 0.05% per generation between 10 821 and 7055 yr BP, then gently grew at 0.58% per generation until 2500 yr BP. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’

Use of urease inhibitors to reduce ammonia volatilization in Amazonian soils.

Made available in DSpace on 2020-01-21T18:22:22Z (GMT). No. of bitstreams: 1 Barberenaetal.2019.pdf: 846211 bytes, checksum: 62a20ad6265f0815c390e4387cc19f9c (MD5) Previous issue date: 2019bitstream/item/209268/1/Barberena-et-al.-2019.pd

Volatilização de amônia de ureias com ou sem inibidores de urease, submetidas a diferentes lâminas de irrigação.

O objetivo neste trabalho foi avaliar a volatilização de amônia de ureias com ou sem inibidores de urease, submetidas a diferentes lâminas de irrigação

Getting Ready for the Next Step: The Eradication of Feral Cats on Large and Highest Priority Mexican Islands

Mexican islands’ biodiversity is very rich and diverse; several reptile, bird, and mammal endemic species live on them. However, ecological and evolutionary processes have been negatively affected by invasive species. To date, more than 20 island endemics, including mammals, birds and reptiles, have gone extinct on Mexican islands. As a very opportunistic predator that adapts easily to different environments, the feral cat is one of the most lethal invasive species. Restoration of island ecosystems can be achieved effectively by the eradication of this noxious species. In Mexico, 18 islands (<400 km2) have been cleared of feral cats using traditional techniques, i.e. trapping and hunting. These techniques are still being implemented on smaller islands or on islands where populations are small. Nevertheless, on big islands with complex terrain and topography, varied habitats and climates, and with non-target species, there are challenges to overcome. This includes Socorro (130 km2), Cerralvo (135 km2), and Guadalupe (240 km2) Islands. To achieve successful cat eradications on these islands, dispersion of toxic baits will be necessary. Currently, bait trials are being developed by Grupo de Ecología y Conservación de Islas, A.C., and supported by Australian and New Zealand institutions, as part of island-specific eradication plans. To date, these studies comprise feral cat and native species ecology for Cerralvo and Socorro Islands. All data gathered is valuable for eradication planning

Compostos orgânicos como alternativa para redução da perda de nitrogênio por volatilização.

A ureia é o fertilizante nitrogenado mais utilizado no Brasil e no mundo. Entretanto, a eficiência da ureia é reduzida devido às perdas de nitrogênio causadas pela volatilização de amônia (NH3) resultante da ação da urease, uma enzima extracelular produzida por microrganismos presentes no solo. Atualmente existem algumas alternativas para minimizar as perdas de nitrogênio da ureia e melhorar sua absorção pelas culturas. Dentre estas, destacam-se os inibidores de urease, sendo o mais conhecido o tiofosfato de N-(n-butil)triamida (NBPT). Outras substâncias têm sido investigadas com relação ao potencial de inibição da enzima urease, porém, poucas têm obtido resultados promissores. Neste contexto, o estudo objetivou avaliar o efeito de compostos orgânicos na redução da volatilização de amônia, em condições edafoclimáticas da Amazônia Sul Ocidental.

Ammonia loss from protected urea in soil under different irrigation depths.

This study presents an evaluation of the viability of using protected urea under different irrigation depths to reduce nitrogen losses caused by the volatilization of ammonia (NH3) under the conditions of the Southwestern Amazon. The study was carried out at the Experimental Station of Embrapa Rondônia, in the municipality of Porto Velho, Rondônia State, Brazil. The experiment was conducted in a Red-Yellow Latosol and arranged in a 5 x 6 factorial design consisting of a combination of five treatments (N sources) with six irrigation depths. The sources of N were as follows: 1) urea (45.5% N); 2) urea (44.3% N) + 0.15% copper and 0.4% boron; 3) urea (45% N) + NBPT; 4) urea (43% N) + sulfur (1%); and 5) control (without N). The irrigation depths were 0, 5, 10, 15, 20, and 25 mm. The results showed that, regardless of the use of urease inhibitors, an irrigation depth of 10 mm is suitable for incorporating urea into the soil and stabilizing N losses from NH3 volatilization. NBPT is the most efficient inhibitor under nonirrigated conditions. All N sources promote increases in the concentrations of nitric and ammonia nitrogen in the soil. In the first 15 days after fertilizer application, the highest concentrations of ammonium were in the 0 - 10 cm and 10 - 20 cm soil layers, and NBPT showed the highest ammonium content compared to that of the other sources in the 0 - 10 cm layer. The nitric nitrogen content in the soil was slightly influenced by the irrigation depth in the first 15 days after fertilizer application. However, the ammonia nitrogen content decreased exponentially with the increase in irrigation depth due to the movement of ammonia in the soil

The higher-level phylogeny of Archosauria (Tetrapoda:Diapsida)

Crown group Archosauria, which includes birds, dinosaurs, crocodylomorphs, and several extinct Mesozoic groups, is a primary division of the vertebrate tree of life. However, the higher-level phylogenetic relationships within Archosauria are poorly resolved and controversial, despite years of study. The phylogeny of crocodile-line archosaurs (Crurotarsi) is particularly contentious, and has been plagued by problematic taxon and character sampling. Recent discoveries and renewed focus on archosaur anatomy enable the compilation of a new dataset, which assimilates and standardizes character data pertinent to higher-level archosaur phylogeny, and is scored across the largest group of taxa yet analysed. This dataset includes 47 new characters (25% of total) and eight taxa that have yet to be included in an analysis, and total taxonomic sampling is more than twice that of any previous study. This analysis produces a well-resolved phylogeny, which recovers mostly traditional relationships within Avemetatarsalia, places Phytosauria as a basal crurotarsan clade, finds a close relationship between Aetosauria and Crocodylomorpha, and recovers a monophyletic Rauisuchia comprised of two major subclades. Support values are low, suggesting rampant homoplasy and missing data within Archosauria, but the phylogeny is highly congruent with stratigraphy. Comparison with alternative analyses identifies numerous scoring differences, but indicates that character sampling is the main source of incongruence. The phylogeny implies major missing lineages in the Early Triassic and may support a Carnian-Norian extinction event.Marshall Scholarship for study in the United KingdomJurassic FoundationUniversity of BristolPaleontological Societ