Abstract Current knowledge on the effects of farming type and landscape heterogeneity on plant di... more Abstract Current knowledge on the effects of farming type and landscape heterogeneity on plant diversity is biased towards temperate ecosystems in Europe and North America, while there is a paucity of information for the Mediterranean agroecosystems. In particular, the Mediterranean region of Central Chile concentrates most of the country's population and have experienced the greatest agricultural changes leading to the replacement of native vegetation remnants by monocultures and livestock ranching. This study aims to analyse the effects of farming type (organic versus conventional) and landscape heterogeneity (composition and configuration), in addition with local habitat type, on semi-natural vegetation. We addressed these effects considering both native and exotic herbs at 14 fruit farms and landscape metrics at three spatial scales (0.5, 1 and 2 km). In total, we recorded 32 native and 103 exotic plant taxa. Farming type and local habitat type did not influence the diversity of native and exotic herbs. We showed that increasing landscape compositional heterogeneity (i.e. percentage of grasslands, of woody elements) increased alpha and beta diversity of native herbs at the scale of 0.5 km and 2 km. Gamma diversity of native plants responded negatively to decreasing landscape configurational heterogeneity (i.e. largest patch index) at the scale of 0.5 km. Exotic specis did not respond to landscape context. Our findings suggest that semi-natural elements in the surrounding landscape of fruit farms particularly benefited native plant species. Therefore, agri-environment schemes designed to preserve native biodiversity in Mediterranean agroecosystems must promote landscape heterogeneity through the conservation of semi-natural elements at multiple spatial scales.
El Niño events, the lean versus fat scenario, and long-term guild dynamics of vertebrate predator... more El Niño events, the lean versus fat scenario, and long-term guild dynamics of vertebrate predators in a South
Arid ecosystems are strongly limited by water availability, and precipitation plays a major role ... more Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.</p
The Darwin's fox (Lycalopex fulvipes) is one of the most endangered carnivores worldwide, wit... more The Darwin's fox (Lycalopex fulvipes) is one of the most endangered carnivores worldwide, with the risk of disease spillover from domestic dogs being a major conservation threat. However, lack of epidemiologic information about generalist, non-dog-transmission-dependent protozoal and bacterial pathogens may be a barrier for disease prevention and management. To determine the exposure of some of these agents in Darwin's fox populations, 54 serum samples were collected from 47 Darwin's foxes in Southern Chile during 2013-18 and assessed for the presence of antibodies against Brucella abortus, Brucella canis, Coxiella burnetii, pathogenic Leptospira (serovars Grippotyphosa, Pomona, Canicola, Hardjo, and Copehageni), Toxoplasma gondii, and Neospora caninum. The highest seroprevalence was detected for T. gondii (78%), followed by pathogenic Leptospira (14%). All the studied Leptospira serovars were confirmed in at least one animal. Two foxes seroconverted to Leptospira and one to T. gondii during the study period. No seroconversions were observed for the other pathogens. No risk factors, either intrinsic (sex, age) or extrinsic (season, year, and degree of landscape anthropization), were associated with the probability of being exposed to T. gondii. Our results indicate that T. gondii exposure is widespread in the Darwin's fox population, including in areas with minimal anthropization, and that T. gondii and pathogenic Leptospira might be neglected threats to the species. Further studies identifying the causes of morbidity and mortality in Darwin's fox are needed to determine if these or other pathogens are having individual or population-wide effects in this species.
Abstract The Darwin’s fox is one of the most threatened carnivores worldwide and was thought to o... more Abstract The Darwin’s fox is one of the most threatened carnivores worldwide and was thought to occur in only two isolated areas. Recently this canid was found in the Valdivian Coastal Range, between the previously known populations, but other than their presence, little is known about these populations. Here we report the results of camera trap surveys conducted between 2012 and 2016 (18,872 camera days), including surveys in 30 different sites—distributed along c. 400 km—and monitoring in two contiguous protected areas. Darwin’s fox detection rate was higher when forest cover was higher or when domestic dog (Canis familiaris) detection rate was lower. Given confirmed presence, the detection rate was higher for sites in Chiloe Island, than in the mainland’s Coastal Range. In mainland, we found evidence of dogs’ presence in most of the sites we detected Darwin’s foxes. In the protected areas monitored, Darwin’s foxes were found to use 12% and 15% of the area sampled in 2015 and 2016 respectively, although there was high uncertainty in the 2016 estimates due to low probability of detection. We did not detect Darwin’s foxes in forestry plantations. Our findings provide support for a continuous distribution along the mainland’s Coastal Range and Chiloe Island but we hypothesize—based on the major differences observed in detection rates between these areas—that local densities are lower in mainland than in Chiloe Island. Finally, Darwin’s fox appears to be sensitive to human disturbance and these disturbances, especially dogs, are ubiquitous within its newly discovered range.
Understanding the effects of global climate disruption on biodiversity is important to future con... more Understanding the effects of global climate disruption on biodiversity is important to future conservation efforts. While taxonomic diversity is widely studied, functional diversity of plants, and recently animals, is receiving increasing attention. Most studies of mammals are short-term, focus on temperate habitats, and rely on traits described in the literature rather than generating traits from observations. Unlike previous studies, this long-term field study assessed the factors driving the functional and taxonomic diversity of small-mammal assemblages in dry tropical forests using both traits recorded from literature and a demographic database. We assessed the drivers (abundance and biomass, temperature and rainfall) of taxonomic richness and functional diversity for two rain-driven seasons in two adjacent but distinct forests-upland and lowland (arroyo or riparian) forests. Our analysis found that rainfall, both seasonal and atypical, was the primary factor driving functional ...
ABSTRACT En comparación con otros mamíferos, los carnívoros suelen mostrar altos requerimientos d... more ABSTRACT En comparación con otros mamíferos, los carnívoros suelen mostrar altos requerimientos de espacio y energía, bajas tasas reproductivas, y alto potencial de conflicto con el hombre, que los hace particularmente vulnerables a cambios ambientales y en uso del suelo. Como depredadores, afectan el funcionamiento ecosistémico a través del consumo de presas, por lo que la extinción de carnívoros nativos y su reemplazo por especies exóticas alterarán su diversidad funcional y subsecuentemente el funcionamiento ecosistémico. Esto dependerá de la asociación entre sus respuestas a cambios ambientales y sus rasgos funcionales. En esta exposición se explora dicha asociación a diferentes escalas espaciales. Primero, se analizó una base de datos compilada a partir de información publicada sobre hábitos dietarios de carnívoros sudamericanos. Mediante Bootstrap se puso a prueba la asociación entre sus rasgos funcionales (i.e. especialización y distinción trófica) y su propensión a la extinción según criterios de la IUCN. Luego, contrastando con modelos neutrales (M0) se cuantificó el efecto de distintos escenarios de extinción y de la introducción de especies sobre la diversidad funcional de los carnívoros a escala continental y regional. En general, las especies clasificadas como Amenazadas o Vulnerables mostraron niveles de especialización y distinción trófica mayores, contribuyendo fuertemente a la diversidad funcional. Escenarios de extinción restrictivos predijeron una mayor erosión de la diversidad funcional que la predicha por M0, tendencia acentuada regionalmente por una menor redundancia funcional a esta escala. Al contrario, las especies exóticas mostraron baja especialización y distinción funcional, no compensando las perdidas funcionales por extinción predichas. Entonces, los escenarios de extinción más severos predicen una fauna de carnívoros funcionalmente empobrecida con una mayor representación de depredadores generalistas/oportunistas. Luego, se determinó el efecto de la fragmentación del hábitat y la introducción de perros y gatos domésticos sobre la diversidad funcional de un ensamble de vertebrados depredadores de Chiloé (X Región, Chile). A partir de funciones de incidencia para cada especie, obtenidas empíricamente de registros de ocurrencia en terreno e información sobre sus rasgos funcionales, se predijo la diversidad funcional esperada en fragmentos de bosque nativo que difieren en tamaño, forma y conectividad. Así, se determinó una baja redundancia funcional producto de los efectos positivos sinérgicos del tamaño y complejidad en la forma de los fragmentos, sugiriendo posibles consecuencias de la fragmentación sobre el funcionamiento ecosistémico.
Abstract Current knowledge on the effects of farming type and landscape heterogeneity on plant di... more Abstract Current knowledge on the effects of farming type and landscape heterogeneity on plant diversity is biased towards temperate ecosystems in Europe and North America, while there is a paucity of information for the Mediterranean agroecosystems. In particular, the Mediterranean region of Central Chile concentrates most of the country's population and have experienced the greatest agricultural changes leading to the replacement of native vegetation remnants by monocultures and livestock ranching. This study aims to analyse the effects of farming type (organic versus conventional) and landscape heterogeneity (composition and configuration), in addition with local habitat type, on semi-natural vegetation. We addressed these effects considering both native and exotic herbs at 14 fruit farms and landscape metrics at three spatial scales (0.5, 1 and 2 km). In total, we recorded 32 native and 103 exotic plant taxa. Farming type and local habitat type did not influence the diversity of native and exotic herbs. We showed that increasing landscape compositional heterogeneity (i.e. percentage of grasslands, of woody elements) increased alpha and beta diversity of native herbs at the scale of 0.5 km and 2 km. Gamma diversity of native plants responded negatively to decreasing landscape configurational heterogeneity (i.e. largest patch index) at the scale of 0.5 km. Exotic specis did not respond to landscape context. Our findings suggest that semi-natural elements in the surrounding landscape of fruit farms particularly benefited native plant species. Therefore, agri-environment schemes designed to preserve native biodiversity in Mediterranean agroecosystems must promote landscape heterogeneity through the conservation of semi-natural elements at multiple spatial scales.
El Niño events, the lean versus fat scenario, and long-term guild dynamics of vertebrate predator... more El Niño events, the lean versus fat scenario, and long-term guild dynamics of vertebrate predators in a South
Arid ecosystems are strongly limited by water availability, and precipitation plays a major role ... more Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.</p
The Darwin's fox (Lycalopex fulvipes) is one of the most endangered carnivores worldwide, wit... more The Darwin's fox (Lycalopex fulvipes) is one of the most endangered carnivores worldwide, with the risk of disease spillover from domestic dogs being a major conservation threat. However, lack of epidemiologic information about generalist, non-dog-transmission-dependent protozoal and bacterial pathogens may be a barrier for disease prevention and management. To determine the exposure of some of these agents in Darwin's fox populations, 54 serum samples were collected from 47 Darwin's foxes in Southern Chile during 2013-18 and assessed for the presence of antibodies against Brucella abortus, Brucella canis, Coxiella burnetii, pathogenic Leptospira (serovars Grippotyphosa, Pomona, Canicola, Hardjo, and Copehageni), Toxoplasma gondii, and Neospora caninum. The highest seroprevalence was detected for T. gondii (78%), followed by pathogenic Leptospira (14%). All the studied Leptospira serovars were confirmed in at least one animal. Two foxes seroconverted to Leptospira and one to T. gondii during the study period. No seroconversions were observed for the other pathogens. No risk factors, either intrinsic (sex, age) or extrinsic (season, year, and degree of landscape anthropization), were associated with the probability of being exposed to T. gondii. Our results indicate that T. gondii exposure is widespread in the Darwin's fox population, including in areas with minimal anthropization, and that T. gondii and pathogenic Leptospira might be neglected threats to the species. Further studies identifying the causes of morbidity and mortality in Darwin's fox are needed to determine if these or other pathogens are having individual or population-wide effects in this species.
Abstract The Darwin’s fox is one of the most threatened carnivores worldwide and was thought to o... more Abstract The Darwin’s fox is one of the most threatened carnivores worldwide and was thought to occur in only two isolated areas. Recently this canid was found in the Valdivian Coastal Range, between the previously known populations, but other than their presence, little is known about these populations. Here we report the results of camera trap surveys conducted between 2012 and 2016 (18,872 camera days), including surveys in 30 different sites—distributed along c. 400 km—and monitoring in two contiguous protected areas. Darwin’s fox detection rate was higher when forest cover was higher or when domestic dog (Canis familiaris) detection rate was lower. Given confirmed presence, the detection rate was higher for sites in Chiloe Island, than in the mainland’s Coastal Range. In mainland, we found evidence of dogs’ presence in most of the sites we detected Darwin’s foxes. In the protected areas monitored, Darwin’s foxes were found to use 12% and 15% of the area sampled in 2015 and 2016 respectively, although there was high uncertainty in the 2016 estimates due to low probability of detection. We did not detect Darwin’s foxes in forestry plantations. Our findings provide support for a continuous distribution along the mainland’s Coastal Range and Chiloe Island but we hypothesize—based on the major differences observed in detection rates between these areas—that local densities are lower in mainland than in Chiloe Island. Finally, Darwin’s fox appears to be sensitive to human disturbance and these disturbances, especially dogs, are ubiquitous within its newly discovered range.
Understanding the effects of global climate disruption on biodiversity is important to future con... more Understanding the effects of global climate disruption on biodiversity is important to future conservation efforts. While taxonomic diversity is widely studied, functional diversity of plants, and recently animals, is receiving increasing attention. Most studies of mammals are short-term, focus on temperate habitats, and rely on traits described in the literature rather than generating traits from observations. Unlike previous studies, this long-term field study assessed the factors driving the functional and taxonomic diversity of small-mammal assemblages in dry tropical forests using both traits recorded from literature and a demographic database. We assessed the drivers (abundance and biomass, temperature and rainfall) of taxonomic richness and functional diversity for two rain-driven seasons in two adjacent but distinct forests-upland and lowland (arroyo or riparian) forests. Our analysis found that rainfall, both seasonal and atypical, was the primary factor driving functional ...
ABSTRACT En comparación con otros mamíferos, los carnívoros suelen mostrar altos requerimientos d... more ABSTRACT En comparación con otros mamíferos, los carnívoros suelen mostrar altos requerimientos de espacio y energía, bajas tasas reproductivas, y alto potencial de conflicto con el hombre, que los hace particularmente vulnerables a cambios ambientales y en uso del suelo. Como depredadores, afectan el funcionamiento ecosistémico a través del consumo de presas, por lo que la extinción de carnívoros nativos y su reemplazo por especies exóticas alterarán su diversidad funcional y subsecuentemente el funcionamiento ecosistémico. Esto dependerá de la asociación entre sus respuestas a cambios ambientales y sus rasgos funcionales. En esta exposición se explora dicha asociación a diferentes escalas espaciales. Primero, se analizó una base de datos compilada a partir de información publicada sobre hábitos dietarios de carnívoros sudamericanos. Mediante Bootstrap se puso a prueba la asociación entre sus rasgos funcionales (i.e. especialización y distinción trófica) y su propensión a la extinción según criterios de la IUCN. Luego, contrastando con modelos neutrales (M0) se cuantificó el efecto de distintos escenarios de extinción y de la introducción de especies sobre la diversidad funcional de los carnívoros a escala continental y regional. En general, las especies clasificadas como Amenazadas o Vulnerables mostraron niveles de especialización y distinción trófica mayores, contribuyendo fuertemente a la diversidad funcional. Escenarios de extinción restrictivos predijeron una mayor erosión de la diversidad funcional que la predicha por M0, tendencia acentuada regionalmente por una menor redundancia funcional a esta escala. Al contrario, las especies exóticas mostraron baja especialización y distinción funcional, no compensando las perdidas funcionales por extinción predichas. Entonces, los escenarios de extinción más severos predicen una fauna de carnívoros funcionalmente empobrecida con una mayor representación de depredadores generalistas/oportunistas. Luego, se determinó el efecto de la fragmentación del hábitat y la introducción de perros y gatos domésticos sobre la diversidad funcional de un ensamble de vertebrados depredadores de Chiloé (X Región, Chile). A partir de funciones de incidencia para cada especie, obtenidas empíricamente de registros de ocurrencia en terreno e información sobre sus rasgos funcionales, se predijo la diversidad funcional esperada en fragmentos de bosque nativo que difieren en tamaño, forma y conectividad. Así, se determinó una baja redundancia funcional producto de los efectos positivos sinérgicos del tamaño y complejidad en la forma de los fragmentos, sugiriendo posibles consecuencias de la fragmentación sobre el funcionamiento ecosistémico.
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