54 research outputs found
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Ecologists need robust survey designs, sampling and analytical methods
1. Research that yields conflicting results rightly causes controversy. Where methodological weaknesses are apparent, there is ready opportunity for discord within the scientific community, which may undermine the entire study.
2. We use the debate about the role of dingoes Canis dingo in conservation in Australia as a case study for a phenomenon that is relevant to all applied ecologists, where conflicting results have been published in high quality journals and yet the problems with the methods used in these studies have led to significant controversy.
3. To alleviate such controversies, scientists need to use robust methods to ensure that their results are repeatable and defendable. To date, this has not occurred in Australia’s dingo debate due to the use of unvalidated indices that rely on unsupported assumptions.
4. We highlight the problems that poor methods have caused in this debate. We also reiterate our recommendations for practitioners, statisticians and researchers to work together to develop long-term, multi-site experimental research programmes using robust methods to understand the impacts of dingoes on mesopredators.
5. Synthesis & applications. Incorporating robust methods and appropriate experimental designs are needed to ensure that conservation actions are appropriately focused and are supported with robust results. Such actions will go
a long way towards resolving the debate about the role of dingoes in conservation in Australia, and other, ecological debates
New material of Chirostenotes pergracilis (Theropoda, Oviraptorosauria) from the Campanian Dinosaur Park Formation of Alberta, Canada
Do Lions Panthera leo Actively Select Prey or Do Prey Preferences Simply Reflect Chance Responses via Evolutionary Adaptations to Optimal Foraging?
Research on coursing predators has revealed that actions throughout the predatory behavioral sequence (using encounter rate, hunting rate, and kill rate as proxy measures of decisions) drive observed prey preferences. We tested whether similar actions drive the observed prey preferences of a stalking predator, the African lion Panthera leo. We conducted two 96 hour, continuous follows of lions in Addo Elephant National Park seasonally from December 2003 until November 2005 (16 follows), and compared prey encounter rate with prey abundance, hunt rate with prey encounter rate, and kill rate with prey hunt rate for the major prey species in Addo using Jacobs' electivity index. We found that lions encountered preferred prey species far more frequently than expected based on their abundance, and they hunted these species more frequently than expected based on this higher encounter rate. Lions responded variably to non-preferred and avoided prey species throughout the predatory sequence, although they hunted avoided prey far less frequently than expected based on the number of encounters of them. We conclude that actions of lions throughout the predatory behavioural sequence, but particularly early on, drive the prey preferences that have been documented for this species. Once a hunt is initiated, evolutionary adaptations to the predator-prey interactions drive hunting success
The first oviraptorosaur (Dinosauria: Theropoda) bonebed: Evidence of gregarious behaviour in a maniraptoran theropod
A monodominant bonebed of Avimimus from the Nemegt Formation of Mongolia is the first oviraptorosaur bonebed described and the only recorded maniraptoran bonebed from the Late Cretaceous. Cranial elements recovered from the bonebed provide insights on the anatomy of the facial region, which was formerly unknown in Avimimus. Both adult and subadult material was recovered from the bonebed, but small juveniles are underrepresented. The taphonomic and sedimentological evidence suggests that the Avimimus bonebed represents a perimortem gregarious assemblage. The near absence of juveniles in the bonebed may be evidence of a transient age-segregated herd or ‘flock’, but the behaviour responsible for this assemblage is unclear. Regardless, the Avimimus bonebed is the first evidence of gregarious behaviour in oviraptorosaurs, and highlights a potential trend of increasing gregariousness in dinosaurs towards the end of the Mesozoic
Exploring African lion (Panthera leo) behavioural phenotypes: individual differences and correlations between sociality, boldness and behaviour
Competitive Asymmetries in the Use of Supplementary Food by the Endangered Iberian Lynx (Lynx pardinus)
Background: As a conservation tool, supplementary feeding programs may be directed to specific individuals or sectors of the target population whose productivity or survival is thought to be limited by food scarcity. However, the use of supplemental food by different sex and age classes has received little attention. We studied individual variation in the access of the endangered Iberian lynx (Lynx pardinus) to supplementary food.
Methodology/Principal Findings: From 5349 pictures taken with automatic cameras placed in 25 feeding stations, we identified 28 individuals whose sex and age were known. All individuals known to live in areas subjected to supplementation regularly visited feeding stations. Food consumption was not proportional to expected variations in energy demand within sex and age classes. Food consumption by males was higher than by females, and increased with age, in agreement with a despotic distribution. Food consumption also increased with lynx body mass, and this pattern held for individuals sharing the same breeding territories. The access of inferior competitors increased with the number of feeding stations available within lynx territories.
Conclusions/Significance: All lynx exposed to food supplementation made a regular use of extra food but individuals predicted to be competitively dominant visited stations more frequently than subordinates of the same breeding territory. Our results suggest that insufficient provision of supplementary food could restrict the access of juveniles, or even adult females, to feeding stations. Limited consumption by these target individuals may compromise the efficiency of the supplementary feeding programme at the population level, in endangered species that, as the Iberian lynx, exhibit marked sexual dimorphism in body size.Peer reviewe
Gene Expression Profiling of Preovulatory Follicle in the Buffalo Cow: Effects of Increased IGF-I Concentration on Periovulatory Events
The preovulatory follicle in response to gonadotropin surge undergoes dramatic biochemical, and morphological changes orchestrated by expression changes in hundreds of genes. Employing well characterized bovine preovulatory follicle model, granulosa cells (GCs) and follicle wall were collected from the preovulatory follicle before, 1, 10 and 22 h post peak LH surge. Microarray analysis performed on GCs revealed that 450 and 111 genes were differentially expressed at 1 and 22 h post peak LH surge, respectively. For validation, qPCR and immunocytochemistry analyses were carried out for some of the differentially expressed genes. Expression analysis of many of these genes showed distinct expression patterns in GCs and the follicle wall. To study molecular functions and genetic networks, microarray data was analyzed using Ingenuity Pathway Analysis which revealed majority of the differentially expressed genes to cluster within processes like steroidogenesis, cell survival and cell differentiation. In the ovarian follicle, IGF-I is established to be an important regulator of the above mentioned molecular functions. Thus, further experiments were conducted to verify the effects of increased intrafollicular IGF-I levels on the expression of genes associated with the above mentioned processes. For this purpose, buffalo cows were administered with exogenous bGH to transiently increase circulating and intrafollicular concentrations of IGF-I. The results indicated that increased intrafollicular concentrations of IGF-I caused changes in expression of genes associated with steroidogenesis (StAR, SRF) and apoptosis (BCL-2, FKHR, PAWR). These results taken together suggest that onset of gonadotropin surge triggers activation of various biological pathways and that the effects of growth factors and peptides on gonadotropin actions could be examined during preovulatory follicle development
The mammals of Angola
Scientific investigations on the mammals of Angola started over 150 years
ago, but information remains scarce and scattered, with only one recent published
account. Here we provide a synthesis of the mammals of Angola based on a thorough
survey of primary and grey literature, as well as recent unpublished records. We present
a short history of mammal research, and provide brief information on each species
known to occur in the country. Particular attention is given to endemic and near endemic
species. We also provide a zoogeographic outline and information on the conservation
of Angolan mammals. We found confirmed records for 291 native species, most of
which from the orders Rodentia (85), Chiroptera (73), Carnivora (39), and
Cetartiodactyla (33). There is a large number of endemic and near endemic species,
most of which are rodents or bats. The large diversity of species is favoured by the wide range of habitats with contrasting environmental conditions, while endemism tends to
be associated with unique physiographic settings such as the Angolan Escarpment. The
mammal fauna of Angola includes 2 Critically Endangered, 2 Endangered, 11
Vulnerable, and 14 Near-Threatened species at the global scale. There are also 12 data
deficient species, most of which are endemics or near endemics to the countryinfo:eu-repo/semantics/publishedVersio
Evaluating camera trapping as a method for estimating cheetah abundance in ranching areas
n order to accurately assess the status of the cheetah Acinonyx jubatus it is necessary
to obtain data on numbers and demographic trends. However, cheetahs are notoriously
difficult to survey because they occur at very low population densities and are often shy and
elusive. In South Africa the problem is further complicated in areas where land is privately
owned, restricting access, with dense bush and cheetahs that are frequently persecuted.
Cheetahs are individually identifiable by their unique spot patterns, making them ideal
candidates for capture–recapture surveys. Photographs of cheetahs were obtained using
four camera traps placed successively at a total of 12 trap locations in areas of known
cheetah activity within a 300 km² area in the Thabazimbi district of the Limpopo Province.
During 10 trapping periods, five different cheetahs were photographed. These results were
used to generate capture histories for each cheetah and the data were analysed using the
capture–recapture software package CAPTURE. Closure tests indicated that the population
was closed (P = 0.056). The Mh model was used to deal with possible heterogeneous capture
probabilities among individual cheetahs. Closure tests did not reject the model assumption
of population closure (P = 0.056).TheMh model produced a capture probability of 0.17 with an
estimate of 6–14 cheetahs (P = 0.95) and a mean population size of seven cheetahs
(S.E. = 1.93). These results are promising and will be improved with employment of more
camera traps and sampling a larger area
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