Patterns of genetic divergence in the Rio Grande cooter (Pseudemys gorzugi), a riverine turtle inhabiting an arid and anthropogenically modified system.

The lower Rio Grande and Pecos River of the southwest United States have been heavily modified by human activities, profoundly impacting the integrity of their aquatic wildlife. In this context, we focused our study on the population genomics of the Rio Grande Cooter (Pseudemys gorzugi), a freshwater turtle of increasing conservation concern, residing in these two rivers and their tributaries. The genetic data revealed two distinct populations: one in the Pecos and Black Rivers of New Mexico and another in the Rio Grande and Devils River of Texas, with admixed individuals identified at the confluence of the Rio Grande and Pecos River. In addition to having a smaller geographic range, we found lower observed heterozygosity, reduced nucleotide diversity, and a smaller effective population size (Ne) in New Mexico population. Our results depict a significant isolation-by-distance pattern across their distribution, with migration being notably infrequent at river confluences. These findings are pivotal for future conservation and restoration strategies, emphasizing the need to recognize the unique needs of each population.

An integrodifference model for vegetation patterns in semi-arid environments with seasonality.

Vegetation patterns are a characteristic feature of semi-deserts occurring on all continents except Antarctica. In some semi-arid regions, the climate is characterised by seasonality, which yields a synchronisation of seed dispersal with the dry season or the beginning of the wet season. We reformulate the Klausmeier model, a reaction-advection-diffusion system that describes the plant-water dynamics in semi-arid environments, as an integrodifference model to account for the temporal separation of plant growth processes during the wet season and seed dispersal processes during the dry season. The model further accounts for nonlocal processes involved in the dispersal of seeds. Our analysis focusses on the onset of spatial patterns. The Klausmeier partial differential equations (PDE) model is linked to the integrodifference model in an appropriate limit, which yields a control parameter for the temporal separation of seed dispersal events. We find that the conditions for pattern onset in the integrodifference model are equivalent to those for the continuous PDE model and hence independent of the time between seed dispersal events. We thus conclude that in the context of seed dispersal, a PDE model provides a sufficiently accurate description, even if the environment is seasonal. This emphasises the validity of results that have previously been obtained for the PDE model. Further, we numerically investigate the effects of changes to seed dispersal behaviour on the onset of patterns. We find that long-range seed dispersal inhibits the formation of spatial patterns and that the seed dispersal kernel's decay at infinity is a significant regulator of patterning.

Metastability as a Coexistence Mechanism in a Model for Dryland Vegetation Patterns.

Vegetation patterns are a ubiquitous feature of water-deprived ecosystems. Despite the competition for the same limiting resource, coexistence of several plant species is commonly observed. We propose a two-species reaction-diffusion model based on the single-species Klausmeier model, to analytically investigate the existence of states in which both species coexist. Ecologically, the study finds that coexistence is supported if there is a small difference in the plant species' average fitness, measured by the ratio of a species' capabilities to convert water into new biomass to its mortality rate. Mathematically, coexistence is not a stable solution of the system, but both spatially uniform and patterned coexistence states occur as metastable states. In this context, a metastable solution in which both species coexist corresponds to a long transient (exceeding [Formula: see text] years in dimensional parameters) to a stable one-species state. This behaviour is characterised by the small size of a positive eigenvalue which has the same order of magnitude as the average fitness difference between the two species. Two mechanisms causing the occurrence of metastable solutions are established: a spatially uniform unstable equilibrium and a stable one-species pattern which is unstable to the introduction of a competitor. We further discuss effects of asymmetric interspecific competition (e.g. shading) on the metastability property.

Analysis of a model for banded vegetation patterns in semi-arid environments with nonlocal dispersal.

Vegetation patterns are a characteristic feature of semi-arid regions. On hillsides these patterns occur as stripes running parallel to the contours. The Klausmeier model, a coupled reaction-advection-diffusion system, is a deliberately simple model describing the phenomenon. In this paper, we replace the diffusion term describing plant dispersal by a more realistic nonlocal convolution integral to account for the possibility of long-range dispersal of seeds. Our analysis focuses on the rainfall level at which there is a transition between uniform vegetation and pattern formation. We obtain results, valid to leading order in the large parameter comparing the rate of water flow downhill to the rate of plant dispersal, for a negative exponential dispersal kernel. Our results indicate that both a wider dispersal of seeds and an increase in dispersal rate inhibit the formation of patterns. Assuming an evolutionary trade-off between these two quantities, mathematically motivated by the limiting behaviour of the convolution term, allows us to make comparisons to existing results for the original reaction-advection-diffusion system. These comparisons show that the nonlocal model always predicts a larger parameter region supporting pattern formation. We then numerically extend the results to other dispersal kernels, showing that the tendency to form patterns depends on the type of decay of the kernel.

Data on the soil and vegetation properties at the small gully catchment area: Steppe region of Kalmykia Republic (South Russia).

In rural areas, research on the environment in native (untaught) soils is important to understand the rate of pedogenesis and to prevent the problems associated with hidden huger. In this article, original data on vegetation, chemical properties and elemental and mineralogical composition of Kastanozems (Protosalic, Siltic) and Hypersalic Solonetz (Siltic) of the small gully catchment (2 ha in total) located at the NE Ergeni Upland (Western Kalmykia, Russia) were presented. Vegetation was described and cut off (to characterize an aboveground biomass) at 13 key plots of 1 × 1 m. The list of species of the small gully catchment area amounts to 23 species (predominantly, perennial herbs) belonging to 13 families and 11 orders. The main dominants are Artemisia lerchiana, A. austriaca, Festuca valesiaca and Poa bulbosa. Soils were described and sampled in 11 cross-sections and two key plots (0 - 10 cm topsoil sampling). In soil water extracts (79 samples in total), electrical conductivity (EC) and pH were measured. In soil samples, particle size distribution, soil organic carbon and CaCO3 contents, total concentration of all the macro elements, some trace (Cl, Nb, Rb, Th, Y, Zr) and potentially toxic elements (As, Co, Cr, Cu, Ni, Pb, Sr, V, and Zn) were described. Moreover, the concentration of three mobile fractions of elements (Li, Be, B, Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Ba, Cd, Pb) measured using Inductively Coupled Plasma Atomic Emission Spectrometry (AES-ICP) was presented. Geochemical indexes of weathering (R - Silica/Alumina, CIW - Chemical Index of Weathering, CIA - Chemical Index of Alteration, WIP - Weathering Index of Parker, PWI -Product of Weathering Index, Vogt Ratio, PIA - Plagioclase Index of Alteration, STI - Silica-Titanium Index, B/A - Bases/Alumina, B/R - Bases/R2O3, Si/R - Silica/R2O3, Weathering indexes WI-1 and WI-2, Si/Ses - Silica/Sesquioxides, Si/Fe - Silica/Iron, a - Potassium/Sodium, ba-1 - (Potassium-Sodium)/Alumina, ba-2 - (Calcium-Magnesium)/Alumina, Ba - (Potassium-Sodium-Calcium)/Alumina) were calculated. In 12 bulk soil samples from Kastanozems and Solonetz, mineralogy (X-Ray diffractometry, the Rietveld full-pattern fitting method for quantitative analysis) was described. Data obtained can be used for more confident identification of pollution sources and pollutants' migration routes, as well as for more effective land-use management, calculating the required doses of nutrients and for adaptation of land use.

Habitat selection by a threatened desert amphibian.

Habitat degradation and fragmentation are major drivers of amphibian declines. The loss of environmental features that allow for movement between water sources may be particularly detrimental for amphibians in arid environments. Climate changes will increase the importance of microhabitats to amphibians. Enhancing areas to facilitate movement may be a necessary conservation strategy for many animal species that depend on wetlands, including federally threatened Chiricahua leopard frogs (Lithobates chiricahuensis). Habitat preferences of this frog species are not well understood. We sought to better understand fine-scale habitat selection, to inform conservation of Chiricahua leopard frogs. We conducted our study on the Ladder Ranch, a privately owned working bison ranch in New Mexico, USA that supports a large proportion of the remaining Chiricahua leopard frogs in the state. We attached radio transmitters to 44 frogs during summer 2014. We located each frog daily for up to 8 weeks (median = 30 days). We assessed fine-scale habitat selection by comparing characteristics at each frog location and a random location 5 m away using conditional logistic regression. Frogs preferred features that likely reduce desiccation, even after accounting for the presence of water. Frogs selected areas with more low-lying cover, especially aquatic vegetation and woody debris, a tree overstory, and a mud substrate. We recommend managing potential movement corridors for Chiricahua leopard frogs by ensuring the presence of muddy creek bottoms, woody debris, riparian overstory, low-lying ground cover, and pools. Microclimates created by these features seem especially valuable given warming temperatures and modified precipitation regimes, resulting in decreased surface water, soil moisture, and vegetation cover. Retaining or creating preferred habitat features and microclimates in areas between water sources may increase connectivity among isolated populations of Chiricahua leopard frogs and could improve persistence and recovery of other water-obligate species in arid landscapes.

An energy-landscape integrated analysis to evaluate agroecological scarcity.

Agrarian landscapes theoretically provide ecosystem services that meet the demands of a wide range of socioecological processes. Consequently, any landscape agroecology approach must tackle the dynamic interaction of land-use distribution and associated social metabolism at different spatiotemporal scales. An agroecological scarcity case study explores how driven agricultural energy flows interact with landscape complexity in arid landscapes of 46 counties in the Qazvin Province (Iran). An Energy-Landscape Integrated Analysis (ELIA) was performed to correlate the energy reinvestment (E) and energy redistribution (I) present within the social metabolism network, with landscape complexity (Le) measured in terms of spatial patterns and related ecological processes. As well, a cluster analysis was run to establish agrarian landscape typologies based on the ELIA indicators. The results of this study provide an explicit sketch of the four strategies that society in Qazvin Province has developed within the dry environments that sustain it. Our findings confirm the hypothesis that there is a positive relationship between optimizing non-dissipative internal energy loops and landscape complexity, which can explain agroecosystem sustainability. This research enables us to define spatially informed agroecological transitions from a territorially explicit socioecological perspective and will make a significant contribution to decisions on agricultural policies given different land-use strategies, especially under scenarios of ecological scarcity.

Cattle-induced eutrophication favours disease-vector mosquitoes.

Free-range cattle rearing in arid landscapes contributes profoundly to ecosystem degradation. Cattle dung nutrification in aquatic habitats potentially shapes species diversity and abundance due to resource availability. These nutrient-enriched environments may increase oviposition by mosquitoes and influence proliferation of disease vectors. Here, we examined mosquito larval abundance of Culex pipiens pipiens (culicine) and an unidentified Anopheles (anopheline) species across different concentration treatments of nutrient (cattle dung) loadings (T1-T4; 1 g L-1, 2 g L-1, 4 g L-1 and 8 g L-1, respectively) in a randomised outdoor mesocosm experiment. The experiment was run for two weeks post-dung inoculation (Day 7 to 21), with mosquito larvae collected (Day 14 and 21), identified and quantified. Higher dung nutrient concentrations significantly increased mosquito larval abundance relative to dung-free controls. Culicine larvae were 26-times more abundant than anopheline on average. Higher dung concentrations also tended to promote more rapid development in larval mosquitoes. With no colonisation by mosquito larvae in the control treatments, we conclude that the input of dung in aquatic ecosystems promotes vector development and abundance with the potential to increase risk of mosquito-borne infections. We therefore recommend sustainable management policies that tackle likely ecological disservices attributable to free-ranging livestock communities.