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result(s) for
"Sholto Douglas"
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Context dependency of top-down, bottom-up and density-dependent influences on cheetah demography
by
Fattebert, Julien
,
Jachowski, David S.
,
Hunter, Luke T. B.
in
Acinonyx jubatus
,
adults
,
animal ecology
2020
Research on drivers of demographic rates has mostly focused on top predators and their prey, and comparatively less research has considered the drivers of mesopredator demography. Of those limited studies, most focused on top‐down effects of apex predators on mesopredator population dynamics, whereas studies investigating alternative mechanisms are less common. In this study, we tested hypotheses related to top‐down, bottom‐up and density‐dependent regulation of demographic rates in an imperilled mesopredator, the cheetah (Acinonyx jubatus). We used a 25‐year dataset of lion density, cheetah density and prey density from the Mun‐Ya‐Wana Conservancy in South Africa and assessed the effects of top‐down, bottom‐up and density‐dependent drivers on cheetah survival and reproduction. In contrast to the top‐down and bottom‐up predictions, both adult and juvenile cheetahs experienced the lowest survival during months with high prey densities and low lion densities. We observed support only for a density‐dependent response in juvenile cheetahs, where they had a higher probability of reaching independence during times with low cheetah density and low prey density. We did not identify any strong drivers of litter size. Collectively, our results indicate that high apex predator abundance might not always have negative effects on mesopredator populations, and suggest that context dependency in top‐down, bottom‐up and density‐dependent factors may regulate demographic rates of cheetahs and other mesopredators. Our results highlight the complexities of population‐level drivers of cheetah demographic rates and the importance of considering multiple hypotheses of mesopredator population regulation. The authors used a long‐term dataset to investigate drivers of cheetah reproduction and survival. They found that top‐down, bottom‐up, and density‐dependent effects on cheetah demography are context dependent and that high densities of apex predators do not always have negative effects on mesopredator demography, illustrating the importance of considering multiple drivers of mesopredator demography simultaneously.
Journal Article
A New Suite of Plasmid Vectors for Fluorescence-Based Imaging of Root Colonizing Pseudomonads
by
Brennan, Melissa B.
,
Johnson, Jessica L.
,
Kemner, Kenneth M.
in
BASIC BIOLOGICAL SCIENCES
,
biocontrol strain
,
Biological control
2018
In the terrestrial ecosystem, plant-microbe symbiotic associations are ecologically and economically important processes. To better understand these associations at structural and functional levels, different molecular and biochemical tools are applied. In this study, we have constructed a suite of vectors that incorporates several new elements into the rhizosphere stable, broad-host vector pME6031. The new vectors are useful for studies requiring multi-color tagging and visualization of plant-associated, Gram-negative bacterial strains such as
plant growth promotion and biocontrol strains. A number of genetic elements, including constitutive promoters and signal peptides that target secretion to the periplasm, have been evaluated. Several next generation fluorescent proteins, namely mTurquoise2, mNeonGreen, mRuby2, DsRed-Express2 and E2-Crimson have been incorporated into the vectors for whole cell labeling or protein tagging. Secretion of mTurquoise2 and mNeonGreen into the periplasm of
SBW25 has also been demonstrated, providing a vehicle for tagging proteins in the periplasmic compartment. A higher copy number version of select plasmids has been produced by introduction of a previously described
mutation, affording an increase in protein expression levels. The utility of these plasmids for fluorescence-based imaging is demonstrated by root colonization of
seedlings by
SBW25 in a hydroponic growth system. The plasmids are stably maintained during root colonization in the absence of selective pressure for more than 2 weeks.
Journal Article
Elemental and Redox Analysis of Single Bacterial Cells by X-ray Microbeam Analysis
by
O'Loughlin, Edward J.
,
Schneegurt, Mark A.
,
Kulpa, Charles F.
in
Bacteria
,
Bacterial Adhesion
,
Bacteriological methods and techniques used in bacteriology
2004
High-energy x-ray fluorescence measurements were used to make elemental maps and qualitative chemical analyses of individual Pseudomonas fluorescens strain NCIMB 11764 cells. Marked differences between planktonic and adhered cells were seen in the morphology, elemental composition, and sensitivity to Cr(VI) of hydrated cells at spatial scales of 150 nm. This technology can be applied to natural geomicrobiological systems.
Journal Article
Lymphoedema-distichiasis and FOXC2: unreported mutations, de novo mutation estimate, families without coding mutations
by
Brice, Glen
,
Sarfarazi, Mansoor
,
Jeffery, Steve
in
Amino Acid Sequence
,
Amino acids
,
Biological and medical sciences
2005
Lymphoedema-distichiasis (LD) is a syndromic form of primary lymphoedema, where mutations in the gene for the developmental transcription factor FOXC2 have been shown to be causative. The disorder has been considered very rare, but our group has now ascertained 34 families and 11 sporadic cases in the UK. Two families with LD have no mutation in the coding region of FOXC2, although both are consistent with linkage to the FOXC2 locus. A deletion has been ruled out as a possible cause of LD in these families, leaving promoter mutations as the most likely cause. Sixteen previously unpublished mutations are reported, plus an estimate of the frequency of new mutations in this disorder.
Journal Article
Habitat complexity and lifetime predation risk influence mesopredator survival in a multi-predator system
by
Fattebert, Julien
,
Jachowski, David S.
,
Hunter, Luke T. B.
in
631/158/1745
,
631/158/853
,
Acinonyx - physiology
2020
Variability in habitat selection can lead to differences in fitness; however limited research exists on how habitat selection of mid-ranking predators can influence population-level processes in multi-predator systems. For mid-ranking, or mesopredators, differences in habitat use might have strong demographic effects because mesopredators need to simultaneously avoid apex predators and acquire prey. We studied spatially-explicit survival of cheetahs (
Acinonyx jubatus
) in the Mun-Ya-Wana Conservancy, South Africa, to test hypotheses related to spatial influences of predation risk, prey availability, and vegetation complexity, on mesopredator survival. For each monitored cheetah, we estimated lion encounter risk, prey density, and vegetation complexity within their home range, on short-term (seasonal) and long-term (lifetime) scales and estimated survival based on these covariates. Survival was lowest for adult cheetahs and cubs in areas with high vegetation complexity on both seasonal and lifetime scales. Additionally, cub survival was negatively related to the long-term risk of encountering a lion. We suggest that complex habitats are only beneficial to mesopredators when they are able to effectively find and hunt prey, and show that spatial drivers of survival for mesopredators can vary temporally. Collectively, our research illustrates that individual variation in mesopredator habitat use can scale-up and have population-level effects.
Journal Article
Movement Demands of an Elite Cricket Team During the Big Bash League in Australia
2020
There is a lack of research on the movement patterns within Twenty20 (T20) cricket, thus the purpose of this study was to investigate the movement demands placed on elite T20 cricket players playing in The Big Bash League, in Australia, in the 2017/2018 season. Player positional movements were determined from the time motion data obtained from a portable 10 Hz global positioning (GPS) unit. Overall, all the players covered between 1.77km and 6.54km in a time ranging between 40.4 minutes and 96.5 minutes. Fast bowlers covered a mean distance of 6.5 (±0.5) km, batsmen 1.7 (±1.2) km and fielders 5.9 (±0.9) km. This is the first study that has looked at the movement demands of players in The Big Bash League and found that bowlers have the highest movement demands followed by fielding. With that, arguably, more attention needs to be devoted to bowling and particularly fielding which is often not prioritized. However, overall demands of T20 cricketers have decreased. Cricketers and coaches need to ensure that they adapt training to ensure that their players are physically prepared for the associated demands.
Journal Article
Factors driving the discovery and utilization of a newly available area by African elephants
by
Chamaillé-Jammes, Simon
,
Pandraud, Anne
,
Shrader, Adrian M.
in
Animals
,
Biodiversity and Ecology
,
Elephants
2020
For large mammals, area expansion is a key conservation measure to prevent species' decline and extinction. Yet, its success depends on whether animals discover and later use these areas. Here, using GPS data, we investigated how herds of elephants detected and used an area made available to them after the removal of a fence. We studied the elephants' behaviour before and after the fence removal, accounting for seasonal changes in movement patterns. In contrast to previous studies, herds visited the newly available area within a month of the fence removal, and the maximum distance they moved into the new area was reached between 5 and 9 months after the fence removal. Yet, elephants did not preferentially visit the new area at night. By the second year, all herds had shifted their seasonal home ranges and incorporated the new area, in contrast to a previous range expansion event. Our analyses show that the regular proximity of elephants to the original fence, and the fact that the new area was generally composed of preferred habitats of the elephants, probably explained the rapid discovery and use of the area. Our study improves our understanding of animal exploration and the role of habitat quality, and thus may improve range expansion and corridor programmes.
Journal Article
The reintroduction of large carnivores to the Eastern Cape, South Africa: an assessment
by
Hayward, Matt W.
,
O'Brien, John
,
Kerley, Graham I. H.
in
Acinonyx jubatus
,
Carnivores
,
Carrying capacity
2007
Recently, conservation estate in South Africa's Eastern Cape Province has increased 10-fold resulting in large predators being increasingly reintroduced to restore ecological integrity and maximize tourism. We describe the reintroductions of large carnivores (>10 kg) that have occurred in the Eastern Cape and use various criteria to assess their success. Lion Panthera leo reintroduction has been highly successful with a population of 56 currently extant in the region and problems of overpopulation arising. The African wild dog Lycaon pictus population has increased to 24 from a founder population of 11. Preliminary results for spotted hyaenas Crocuta crocuta also indicate success. Wild populations of leopards Panthera pardus exist on several reserves and have been supplemented by translocated individuals, although deaths of known individuals have occurred and no estimate of reproduction is available. Cheetah Acinonyx jubatus reintroduction has also been less successful with 36 individuals reintroduced and 23 cubs being born but only 41 individuals surviving in 2005. Criteria for assessing the success of reintroductions of species that naturally occur in low densities, such as top predators, generally have limited value. Carrying capacity for large predators is unknown and continued monitoring and intensive management will be necessary in enclosed, and possibly all, conservation areas in the Eastern Cape to ensure conservation success.
Journal Article
Integrated Dynamic 3D Imaging of Microbial Processes and Communities in Rhizosphere Environments: The Argonne Small Worlds Project
by
O'Brien, S.
,
Ahrendt, A.
,
Austin, J.
in
Analytical and Instrumentation Science Symposia
,
Bridging Length Scales with 2D, 3D, and 4D Multiscale/Multimodal Microscopy
2017
Journal Article