Browsing by Author "Beaudrot, Lydia"
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Item Consistent diel activity patterns of forest mammals among tropical regions(Springer Nature, 2022) Vallejo-Vargas, Andrea F.; Sheil, Douglas; Semper-Pascual, Asunción; Beaudrot, Lydia; Ahumada, Jorge A.; Akampurira, Emmanuel; Bitariho, Robert; Espinosa, Santiago; Estienne, Vittoria; Jansen, Patrick A.; Kayijamahe, Charles; Martin, Emanuel H.; Lima, Marcela Guimarães Moreira; Mugerwa, Badru; Rovero, Francesco; Salvador, Julia; Santos, Fernanda; Spironello, Wilson Roberto; Uzabaho, Eustrate; Bischof, Richard; Program in Ecology & Evolutionary BiologyAn animal’s daily use of time (their “diel activity”) reflects their adaptations, requirements, and interactions, yet we know little about the underlying processes governing diel activity within and among communities. Here we examine whether community-level activity patterns differ among biogeographic regions, and explore the roles of top-down versus bottom-up processes and thermoregulatory constraints. Using data from systematic camera-trap networks in 16 protected forests across the tropics, we examine the relationships of mammals’ diel activity to body mass and trophic guild. Also, we assess the activity relationships within and among guilds. Apart from Neotropical insectivores, guilds exhibited consistent cross-regional activity in relation to body mass. Results indicate that thermoregulation constrains herbivore and insectivore activity (e.g., larger Afrotropical herbivores are ~7 times more likely to be nocturnal than smaller herbivores), while bottom-up processes constrain the activity of carnivores in relation to herbivores, and top-down processes constrain the activity of small omnivores and insectivores in relation to large carnivores’ activity. Overall, diel activity of tropical mammal communities appears shaped by similar processes and constraints among regions reflecting body mass and trophic guilds.Item Functional diversity and redundancy of tropical forest mammals over time(Wiley, 2021) Gorczynski, Daniel; Beaudrot, Lydia; Program in Ecology and Evolutionary BiologyGlobally, tropical rain forests comprise some of the most diverse and functionally rich ecosystems but are increasingly degraded by human impacts. Protected areas have been shown to conserve species diversity, but their effectiveness at maintaining functional diversity over time is less well known, despite the fact that functional diversity likely reveals more ecological information than taxonomic diversity. By extension, the degree to which species loss decreases functional diversity within protected areas is also unknown; functional redundancy may buffer communities from loss of functional diversity from some local extinctions. Using eight years of camera trap data, we quantified annual functional dispersion of the large mammal community in the Volcán Barva region of Costa Rica and tested for changes in functional dispersion over time in response to environmental and anthropogenic predictors. We quantified functional redundancy based on simulated declines in functional dispersion with species loss. Observed functional dispersion did not change significantly over time and was not associated with measured environmental or anthropogenic predictors. Quantitative modeling of observed functional traits over time did not identify significant changes. We did however find qualitative trends in relative trait proportions, which could be indicative of functional change in the future. We found high functional redundancy, with average simulated functional dispersion declining significantly only after 9 out of 21 large mammal species were lost from the community. We cautiously suggest that protected tropical rain forests can conserve functional diversity over the course of a decade even in heavily fragmented landscapes.Item Measuring understorey vegetation structure using a novel mixed-reality device(Wiley, 2022) Gorczynski, Daniel; Beaudrot, Lydia; Program in Ecology and Evolutionary BiologyMost ecological studies of vegetation structure have relied on manual field measurements that are labour-intensive and time-consuming. Many current alternatives to classical measurements are expensive or difficult to transport to field settings. Here we evaluated a new method for measuring understorey vegetation with a novel mixed-reality, remote sensing device, the Microsoft HoloLens. We developed a vegetation sensing application called VegSense that allows the HoloLens user to control the device's environmental scanners to measure understorey vegetation. Using VegSense, we tested the ability of the Microsoft HoloLens relative to classical field measurements to (a) detect trees and saplings, (b) measure diameter at breast height (DBH), (c) detect individual understorey vegetation structures and (d) estimate understorey vegetation complexity replicating the rod-transect method. We found that VegSense performed well in detecting and measuring trees with a DBH of 17 cm or more and estimating vegetation complexity and performed moderately at detecting understorey vegetation. Our results indicate that the HoloLens is a suitable alternative for multiple classical field measurements of understorey vegetation. This method costs much less than typical terrestrial LiDAR systems, and can facilitate efficient, high-quality environmental data collection. Further software development has the potential to reveal additional ways in which this device can be harnessed for applications to ecology and evolution.Item Occupancy winners in tropical protected forests: a pantropical analysis(The Royal Society, 2022) Semper-Pascual, Asunción; Bischof, Richard; Milleret, Cyril; Beaudrot, Lydia; Vallejo-Vargas, Andrea F.; Ahumada, Jorge A.; Akampurira, Emmanuel; Bitariho, Robert; Espinosa, Santiago; Jansen, Patrick A.; Kiebou-Opepa, Cisquet; Moreira Lima, Marcela Guimarães; Martin, Emanuel H.; Mugerwa, Badru; Rovero, Francesco; Salvador, Julia; Santos, Fernanda; Uzabaho, Eustrate; Sheil, Douglas; Program in Ecology and Evolutionary BiologyThe structure of forest mammal communities appears surprisingly consistent across the continental tropics, presumably due to convergent evolution in similar environments. Whether such consistency extends to mammal occupancy, despite variation in species characteristics and context, remains unclear. Here we ask whether we can predict occupancy patterns and, if so, whether these relationships are consistent across biogeographic regions. Specifically, we assessed how mammal feeding guild, body mass and ecological specialization relate to occupancy in protected forests across the tropics. We used standardized camera-trap data (1002 camera-trap locations and 2–10 years of data) and a hierarchical Bayesian occupancy model. We found that occupancy varied by regions, and certain species characteristics explained much of this variation. Herbivores consistently had the highest occupancy. However, only in the Neotropics did we detect a significant effect of body mass on occupancy: large mammals had lowest occupancy. Importantly, habitat specialists generally had higher occupancy than generalists, though this was reversed in the Indo-Malayan sites. We conclude that habitat specialization is key for understanding variation in mammal occupancy across regions, and that habitat specialists often benefit more from protected areas, than do generalists. The contrasting examples seen in the Indo-Malayan region probably reflect distinct anthropogenic pressures.Item The Functional Side of Diversity: Effects of Environmental Conditions and Human Disturbance on Tropical Forest Mammal Communities(2023-07-13) Gorczynski, Daniel; Beaudrot, LydiaBiodiversity provides many benefits to humans, but human activity is rapidly driving the loss of biodiversity, particularly in the tropics. Relevant species characteristics such as body size and diet, known as traits, provide insight into the biological roles of diverse species in an ecosystem. Little is known about the trait diversity of large mammals in tropical rainforests because of the reclusive nature of these species but increasing our knowledge can provide important information about critical ecosystem functions performed by mammals. In addition, many tropical mammals are currently endangered, threatening the persistence of their ecological functions. To address this pressing issue in this dissertation, I investigate how environmental and anthropogenic conditions affect mammal trait diversity in tropical rainforests around the world. This work overcomes prior data limitations by using data from the largest tropical forest remote camera monitoring network in the world. I assess the ecological drivers of trait diversity at an unprecedented scope and scale by coupling these data with cutting-edge remote sensing techniques. First, I found that mammal trait diversity remained constant over the course of a decade within a Costa Rican national park surrounded by a human dominated landscape, potentially due to high functional redundancy among this mammal community. Second, in a global comparison of 15 tropical forest national parks, I found that trait diversity was higher in parks where the amount of healthy plant growth was higher, while human-induced extinctions reduced trait diversity and therefore degraded ecosystem functions. Third, I investigated how microhabitat characteristics affected species trait diversity in a national park in Tanzania and revealed that higher forest floor habitat surface area was associated with increased mammal trait diversity, and that carnivorous and social species showed preference for higher habitat surface area. Finally, in a global analysis of species spatial overlap, I identified that species with similar traits were more likely to co-occur in the presence of high human density, suggesting that human presence is altering the spatial distribution of ecosystem functions in protected areas, potentially leading to changes in species interactions and increased extinction risk. Together, this dissertation reveals the importance of functional traits for understanding environmental and anthropogenic effects on biodiversity and identify factors that structure the critical ecological roles of mammals in tropical rain forests.