Mammals can show conspicuous behavioral responses to thermal variation,including changes in movement patterns.We used an integrative approach to understand how environmental temperature can drive the movement behavior...Mammals can show conspicuous behavioral responses to thermal variation,including changes in movement patterns.We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation,the giant anteater(Myrmecophaga tridactyla).We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah.We estimated the distance moved,area used,use of forest areas,and mean environmental temperature for each monitoring day of each individual.We modeled these data with Mixed Structural Equations—considering the possible interactions between our variables and controlling for sex and body mass.Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature,probably because of their low body heat production.It is possible that they reduce distance moved and area used by reducing the duration of activity.With decreasing temperature,forest habitats become warmer than open ones,besides buffer rain and chilly winds.Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation.However,decreasing movement can limit food access and,consequently,fitness.Therefore,we highlight the importance of forests as thermal shelters.With increasing frequency and intensity of extreme weather events,we showed the need to preserve forest patches to offer suitable conditions for tropical mammals’behavioral thermoregulation.In this context,policies favoring deforestation on Brazilian territory are especially worrisome.Finally,we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment.展开更多
Being active in the same environment at different times exposes animals to the effects of very different environmental factors,both biotic and abiotic.In the present study,we used live traps equipped with timing devic...Being active in the same environment at different times exposes animals to the effects of very different environmental factors,both biotic and abiotic.In the present study,we used live traps equipped with timing devices to evaluate the potential role of biotic factors(competition and food abundance)on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high-elevation grassland fields(‘campos de altitude’)of southern Brazil.Based on resources availability(invertebrates),data on animal captures were pooled in 2 seasons:‘scarcity’(June 2001−September 2001)and‘abundance’(November 2001-May 2002)seasons.We tested for non-random structure in temporal niche overlap among the species in each season.These species were the rodents Oxymycterus nasutus(Waterhouse,1837),Deltamys sp.,Akodon azarae(Fischer,1829),and the marsupial Monodelphis brevicaudis Olfers,1818.The studied community was mainly diurnal with crepuscular peaks.Simulations using the Pianka index of niche overlap indicated that the empirical assemblage-wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season.All the species showed an increase in temporal niche breadth during the abundance season,which appears to be related to longer daylength and high nocturnal temperatures.Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources.Therefore,we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.展开更多
基金This work was supported by the Brasilian Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPQ(133623/2017-3 to AG and 308934/2017-2 to GM)National Program of post doctorate of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior-CAPES(PNPD 1694744 to ZO)São Paulo Research Foundation-FAPESP(2013/18526-9 and 2013/04957-8 to AB).
文摘Mammals can show conspicuous behavioral responses to thermal variation,including changes in movement patterns.We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation,the giant anteater(Myrmecophaga tridactyla).We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah.We estimated the distance moved,area used,use of forest areas,and mean environmental temperature for each monitoring day of each individual.We modeled these data with Mixed Structural Equations—considering the possible interactions between our variables and controlling for sex and body mass.Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature,probably because of their low body heat production.It is possible that they reduce distance moved and area used by reducing the duration of activity.With decreasing temperature,forest habitats become warmer than open ones,besides buffer rain and chilly winds.Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation.However,decreasing movement can limit food access and,consequently,fitness.Therefore,we highlight the importance of forests as thermal shelters.With increasing frequency and intensity of extreme weather events,we showed the need to preserve forest patches to offer suitable conditions for tropical mammals’behavioral thermoregulation.In this context,policies favoring deforestation on Brazilian territory are especially worrisome.Finally,we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment.
基金This study was supported by British Ecological Society(SEPG#1841)UNISINOS and FAPERGS(0112763)While conducting this research work EM Vieira received a personal research grant from the Conselho Nacional de Pesquisa-CNPq(300286/99-6).All the methods used here comply with the current Brazilian laws on wildlife studies.
文摘Being active in the same environment at different times exposes animals to the effects of very different environmental factors,both biotic and abiotic.In the present study,we used live traps equipped with timing devices to evaluate the potential role of biotic factors(competition and food abundance)on overall overlap in the temporal niche axis of 4 insectivorous small mammals in high-elevation grassland fields(‘campos de altitude’)of southern Brazil.Based on resources availability(invertebrates),data on animal captures were pooled in 2 seasons:‘scarcity’(June 2001−September 2001)and‘abundance’(November 2001-May 2002)seasons.We tested for non-random structure in temporal niche overlap among the species in each season.These species were the rodents Oxymycterus nasutus(Waterhouse,1837),Deltamys sp.,Akodon azarae(Fischer,1829),and the marsupial Monodelphis brevicaudis Olfers,1818.The studied community was mainly diurnal with crepuscular peaks.Simulations using the Pianka index of niche overlap indicated that the empirical assemblage-wide overlap was not significantly different from randomly generated patterns in the abundance season but significantly greater than expected by chance alone in the scarcity season.All the species showed an increase in temporal niche breadth during the abundance season,which appears to be related to longer daylength and high nocturnal temperatures.Patterns on both temporal niche overlap and temporal niche breadth were the opposite to those that we were expecting in the case of diel activity patterns determined by competition for dietary resources.Therefore,we conclude that competition did not seem to be preponderant for determining patterns of temporal niche overlap by the studied community.
