Top-down and bottom-up control on cougar and its prey in a central Mexican natural reserve

Top-down and bottom-up controls are hypothe sized to regulate population structures in many ecosystems. However, few studies have had the opportunity to analyzeboth processes in the natural environment, especially on largecarnivores like the cougar (Puma concolor). Previously, studies show that cougar diet in the Sierra Nanchititla NaturalReserve (SNNR), central Mexico, is mainly armadillo, coati, and white-tailed deer. We assess whether top-down and/or bottom-up control regulate this endangered food web: (a) wepredicted that seasonal per capita changes in abundance (pca) of cougar will be positively affected by the abundance of their main prey; (b) primary productivity in SNNR will affect the pca of prey species, driving bottom-up control; and (c) armadillo, coati, and white-tailed deer pca will be affected by the abundance of cougar, generating top-down control. Using 15 camera traps for 6 years in the SNNR, we calculated a relative abundance index (RAI) and pca for cougar and each of the focal prey, and we used the normalized difference vegetation index (NDVI) as a proxy of primary productivity. We constructed multiple regression models and selected the best linear models based on ranking the AICc values. Our analysis suggests that P. concolor pca is best explained by bottom-up control and intraspecific feedback. White-tailed deer and armadillo pca were both significantly affected by cougar abundance, indicating top-down control for these prey species, but NDVI was not retained in any of the models selected for prey pca. Our results indicate that both bottom-up and top-down control are involved in regulating this endangered food web in the SNNR, Mexico

Ecological and evolutionary implications of food subsidies from humans

Human activities are the main current driver of global change. From hunter-gatherers through to Neolithic societies–and particularly in contemporary industrialised countries–humans have (voluntarily or involuntarily) provided other animals with food, often with a high spatio-temporal predictability. Nowadays, as much as 30–40% of all food produced in Earth is wasted. We argue here that predictable anthropogenic food subsidies (PAFS) provided historically by humans to animals has shaped many communities and ecosystems as we see them nowadays. PAFS improve individual fitness triggering population increases of opportunistic species, which may affect communities, food webs and ecosystems by altering processes such as competition, predator–prey interactions and nutrient transfer between biotopes and ecosystems. We also show that PAFS decrease temporal population variability, increase resilience of opportunistic species and reduce community diversity. Recent environmental policies, such as the regulation of dumps or the ban of fishing discards, constitute natural experiments that should improve our understanding of the role of food supply in a range of ecological and evolutionary processes at the ecosystem level. Comparison of subsidised and non-subsidised ecosystems can help predict changes in diversity and the related ecosystem services that have suffered the impact of other global change agents

Functional responses of cougars (Puma concolor) in a multiple prey-species system

The study of predator-prey interactions is commonly analyzed using functional responses to gain an understanding of predation patterns and the impact they have on prey populations. Despite this, little is known about predator-prey systems with multiple prey species in sites near the equator. Here we studied the functional response of cougars (Puma concolor) in Sierra Nanchititla Natural Reserve (Mexico), in relation to their main prey, armadillo (Dasypus novemcinctus), coati (Nasua narica) and white-tailed deer (Odocoileus virginianus). Between 2004 and 2010, cougar scats were collected along five transects to estimate the consumption of different prey species. A relative abundance index (RAI) was calculated for each prey species and cougar using 18 camera traps. We compared Holling type I, II and III functional response models to determine patterns in prey consumption based on the relative abundance and biomass of each prey species consumed. The three main prey species comprised 55% (armadillo), 17% (coati) and 8% (white-tailed deer) of the diet. Type I and II functional responses described consumption of the two most common prey species armadillos and coati similarly well, while a type I response best characterized consumption of white-tailed deer. A negative correlation between the proportions of armadillo versus coati and white-tailed deer biomass in cougar scats suggests switching to consume alternative prey, confirming high foraging plasticity of this carnivore. This work represents one of the few studies to compare functional responses across multiple prey species, combined with evidence for prey switching at low densities of preferred prey

An Electromyographic Study of Upper Trapezius, Lower Trapezius, and Serratus Anterior Muscle Activity during Traditional and Modified Muscle Testing Positions

Purpose: The purpose of this study is to assess the muscle activity of the shoulder joint force couple induced by the upper trapezius, lower trapezius, and serratus anterior to determine if they are more effectively recruited during the traditional exercise position of forward shoulder elevation in 145° of shoulder abduction versus a modified position of shoulder external rotation while in 80° of shoulder abduction and 90° of elbow flexion Methods: Nine participants took part in this randomized study in which EMG data was collected during 4 exercise trials of 10 repetitions each on the right shoulder. EMG activity was monitored in the upper trapezius, lower trapezius, upper serratus anterior, and lower serratus anterior in the standard manual muscle testing position for the lower trapezius and a modified position with and without a two pound hand weight. The modified position had the shoulder in 80° of shoulder abduction with the elbow flexed to 90°, and palm facing the floor. Results: All subjects were able to complete the study except one who was excluded due to data corruption. Not surprisingly, more EMG activity was found in the four muscles for positions using weight compared to the no weight position regardless of the testing position implemented. The EMG activity, in the modified position, is decreased in the upper trapezius and lower serratus when compared to the standard position. This is true regardless of the presence of the two pound weight. In the lower trapezius and the upper serratus there is no significant difference between the modified and standard positions regardless of the presence of the two pound weight. Conclusion: The modified position recruits similar motor units in the lower trapezius and upper serratus. There is a significant reduction in EMG activity in the upper trapezius and lower serratus when comparing modified and standard testing positions

Road verge vegetation and the capture of particulate matter air pollution

Urban air quality is considered a major issue in cities worldwide, with particulate matter (PM) recognised as one of the most harmful pollutants regarding human health. The use of plants to act as air filters and immobilise PM has been identified as a potential method to improve the air quality in these areas. The majority of the work has focused on trees, with the application of shrub and herbaceous species largely overlooked. Two contrasting leaf morphologies from a shrub and herbaceous plant species were sampled at four locations across Southampton (UK), from varying traffic conditions. Samples were analysed for the mass of PM captured, particle size, and elemental composition. These analyses were used to characterise the different sites and the plants’ effectiveness at immobilisation of PM. Captured PM mass was shown to be directly related to traffic density, with greater traffic density leading to higher levels of captured PM. PM origins were attributed to emissions from vehicles and the resuspension of particles by vehicle movement. The bulk of the PM mass was shown to originate from natural, crustal sources including large proportions of Al, Si, and/or Ca. Increases in elements from anthropogenic enhancement (such as Fe and Zn) were related to high traffic density. Particle size analysis identified that, despite the use of standard leaf-washing protocols with a final 2.5 µm filter, PM was dominated by fine particles (<2.5 µm physical diameter), with particles >10 µm rare. Bramble leaves were calculated to have a species-specific deposition velocity 0.51 cm s−1 greater than ivy, with deposition velocities calculated at 1.8 and 1.3 cm s−1 for ivy and 2.3 and 1.8 cm s−1 for bramble at Redbridge Road and Brinton’s Road, respectively. These values can allow for the more accurate modelling and estimation of the PM removal abilities of these plants

Resin-Transfer-Molding of a Tool Face

A resin-transfer-molding (RTM) process has been devised for fabricating a matrix/graphite-cloth composite panel that serves as tool face for manufacturing other composite panels. Heretofore, RTM has generally been confined to resins with viscosities low enough that they can readily flow through interstices of cloth. The present process makes it possible to use a high-temperature, more-viscous resin required for the tool face. First, a release layer and then a graphite cloth are laid on a foam pattern that has the desired contour. A spring with an inside diameter of 3/8 in. (.9.5 mm) is placed along the long dimension of the pattern to act as a conduit for the resin. Springs with an inside diameter of 1/4 in. (.6.4 mm) are run off the larger lengthwise spring for distributing the resin over the tool face. A glass cloth is laid on top to act as breather. The whole layup is vacuum-bagged. Resin is mixed and made to flow under vacuum assistance to infiltrate the layup through the springs. The whole process takes less than a day, and the exposure of personnel to resin vapors is minimized

Colonization, covariance and colour: environmental and ecological drivers of diversity-stability relationships

Peer reviewe