Browsing by Author "Espinosa, Santiago"

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    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 Biology
    An 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.
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    Evolutionary history and environmental variability structure contemporary tropical vertebrate communities
    (Wiley, 2024) Hsieh, Chia; Gorczynski, Daniel; Bitariho, Robert; Espinosa, Santiago; Johnson, Steig; Lima, Marcela Guimarães Moreira; Rovero, Francesco; Salvador, Julia; Santos, Fernanda; Sheil, Douglas; Beaudrot, Lydia; Program in Ecology and Evolutionary Biology
    Aim Tropical regions harbour over half of the world's mammals and birds, but how their communities have assembled over evolutionary timescales remains unclear. To compare eco-evolutionary assembly processes between tropical mammals and birds, we tested how hypotheses concerning niche conservatism, environmental stability, environmental heterogeneity and time-for-speciation relate to tropical vertebrate community phylogenetic and functional structure. Location Tropical rainforests worldwide. Time period Present. Major taxa studied Ground-dwelling and ground-visiting mammals and birds. Methods We used in situ observations of species identified from systematic camera trap sampling as realized communities from 15 protected tropical rainforests in four tropical regions worldwide. We quantified standardized phylogenetic and functional structure for each community and estimated the multi-trait phylogenetic signal (PS) in ecological strategies for the four regional species pools of mammals and birds. Using linear regression models, we test three non-mutually exclusive hypotheses by comparing the relative importance of colonization time, palaeo-environmental changes in temperature and land cover since 3.3 Mya, contemporary seasonality in temperature and productivity and environmental heterogeneity for predicting community phylogenetic and functional structure. Results Phylogenetic and functional structure showed non-significant yet varying tendencies towards clustering or dispersion in all communities. Mammals had stronger multi-trait PS in ecological strategies than birds (mean PS: mammal = 0.62, bird = 0.43). Distinct dominant processes were identified for mammal and bird communities. For mammals, colonization time and elevation range significantly predicted phylogenetic clustering and functional dispersion tendencies respectively. For birds, elevation range and contemporary temperature seasonality significantly predicted phylogenetic and functional clustering tendencies, respectively, while habitat diversity significantly predicted functional dispersion tendencies. Main conclusions Our results reveal different eco-evolutionary assembly processes structuring contemporary tropical mammal and bird communities over evolutionary timescales that have shaped tropical diversity. Our study identified marked differences among taxonomic groups in the relative importance of historical colonization and sensitivity to environmental change.
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    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 Biology
    The 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.