scholarly journals Factors affecting spatial and temporal dynamics of an ungulate assemblage in the Black Hills, South Dakota

Author(s):  
Barbara Jean Keller
2020 ◽  
Author(s):  
Bethan Morris ◽  
Lee Curtin ◽  
Andrea Hawkins-Daarud ◽  
Matthew E. Hubbard ◽  
Ruman Rahman ◽  
...  

AbstractGlioblastomas (GBMs) are the most aggressive primary brain tumours and have no known cure. Each individual tumour comprises multiple sub-populations of genetically-distinct cells that may respond differently to targeted therapies and may contribute to disappointing clinical trial results. Image-localized biopsy techniques allow multiple biopsies to be taken during surgery and provide information that identifies regions where particular sub-populations occur within an individual GBM, thus providing insight into their regional genetic variability. These sub-populations may also interact with one another through a competitive or cooperative nature; it is important to ascertain the nature of these interactions, as they may have implications for responses to targeted therapies. We combine genetic information from biopsies with a mechanistic model of interacting GBM sub-populations to characterise the nature of interactions between two commonly occurring GBM sub-populations, those with EGFR and PDGFRA genes amplified. We study population levels found across image-localized biopsy data from a cohort of 25 patients and compare this to model outputs under competitive, cooperative and neutral interaction assumptions. We explore other factors affecting the observed simulated sub-populations, such as selection advantages and phylogenetic ordering of mutations, which may also contribute to the levels of EGFR and PDGFRA amplified populations observed in biopsy data.


2020 ◽  
Vol 98 (9) ◽  
pp. 603-610
Author(s):  
C.M. Soares ◽  
R.I. Dias

The contribution of roads to human economic and social development contrasts with its impact on the environment and wildlife. One of the most significant impacts of roads is wildlife–vehicle collisions. Millions of individuals from numerous species are killed annually around the world. Here we investigated the spatial and temporal dynamics of road killing on a small neotropical bird, the Blue-black Grassquit (Volatinia jacarina (Linnaeus, 1766)). We used a data set of roadkill records collected between 2010 and 2015 to test the hypotheses that roadkills are concentrated during the breeding period of the species and that road features and weather conditions affect the likelihood of animal–vehicle collisions. We observed that the number of fatalities was temporally and spatially clustered. Roadkills were more frequent in warmer, rainy days with lower wind speed. Fatalities were more commonly associated with two-lane roads compared with dirt and four-lane roads. Given that Blue-black Grassquits are attracted to human-modified habitats, especially to artificial grasslands composed of exotic grasses usually found along the margins of roads, mitigation measures should focus on the management and control of grass populations. Roadside mowing may reduce areas where Blue-black Grassquits can establish territories, and consequently, reduce the activity of the species near roads.


2018 ◽  
Vol 27 (1) ◽  
pp. 12-19
Author(s):  
Mohamed Azzaoui ◽  
Benchohra Maamar ◽  
Leila Soudani ◽  
Belgacem Nouar ◽  
Mohamed Berreyah ◽  
...  

The Sdamas massif to which our contribution relates is located in West Algeria, it is an integral part of the Tiaret mountains. The aim of our study is to analyze the land cover of the Sdamas region over a 43-year interval grouped into 9 thematic classes: mineral surfaces (urban planning), wetland, vegetation, bare soils and fallow etc. The spatial and temporal dynamics of land use require regular monitoring of vegetation cover from remote sensing imagery. It is for this reason that we relied on field data to perform the diachronic analysis with three well-defined scenes 1972, 1998 and 2015, using Landsat satellite images (MSS, TM and ETM +). The analysis of these maps covering the same region shows the different changes that have taken place at ground level. We found that our natural plant space has undergone a strong degradation, disruption and regression because of different human activities, namely: overgrazing, clearing, fires, urbanization, (there has been a remarkable increase in the population of the communes of the study area). Inadequate and ineffective forestry interventionsand work, and lack of sustained protection are reasons of these processes. Factors affecting the forest ecosystem are bioclimate and human action. Indeed, the bioclimate, through atmospheric drought, is the main factor governing the diversity of these formations of the Sdamas mountains.


2011 ◽  
Author(s):  
M. Leonard ◽  
N. Ferjan Ramirez ◽  
C. Torres ◽  
M. Hatrak ◽  
R. Mayberry ◽  
...  

2020 ◽  
Vol 637 ◽  
pp. 117-140 ◽  
Author(s):  
DW McGowan ◽  
ED Goldstein ◽  
ML Arimitsu ◽  
AL Deary ◽  
O Ormseth ◽  
...  

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA’s advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.


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