Harald Beck | Towson University (original) (raw)
Papers by Harald Beck
Because of their range expansion across North America, coyotes (Canis latrans) now occur sympatri... more Because of their range expansion across North America, coyotes (Canis latrans) now occur sympatrically with numerous other predator species, including red foxes (Vulpes vulpes). This raises several interesting ecological questions, including if and how sympatry affects the diet and gut microbiomes of coyotes and red foxes. We examined the gut microbiomes of sympatric populations of coyotes and red foxes within two different National Parks in Virginia, USA, that differ in land use, vegetation, and anthropogenic disturbance: Prince William Forest Park (PRWI) and Manassas National Battlefield Park (MANA). From 2012 to 2017, scat samples from PRWI and MANA were collected and analyzed. Polymerase Chain Reaction (PCR) amplification of a region of the mitochondrial cytochrome-b gene followed by restriction enzyme digestion of the PCR product was used to determine the origin of each scat sample. Next-Generation DNA sequencing of a hypervariable 16S rRNA gene region was used to determine gut...
Journal of Tropical Ecology, Aug 31, 2007
Most seedlings and saplings remain in the forest understorey for decades before becoming adults o... more Most seedlings and saplings remain in the forest understorey for decades before becoming adults or dying, and thus may be exposed to various sources of physical disturbance (Clark & Clark 1991, 2001). Because tree species vary in their ability to recover after physical damage (Gillman et al. 2003, Guariguata 1998), this damage can act as an ecological filter and influence the juvenile community structure and species composition (Peters et al. 2004). Studies have demonstrated the occurrence and magnitude of stem breakage in juveniles caused by falling branches and other canopy debris (Clark & Clark 1989, 1991; Gillman & Ogden 2001, Scariot 2000). Surprisingly, little is known about the magnitude and ecological consequences of physical damage to juvenile plants by mammals, particularly large ungulates, including herbivory, trampling and uprooting (Gillman & Ogden 2003, Roldán & Simonetti 2001).
In chapter 1, I investigate the role of heterogeneous landscapes and its effects on the populatio... more In chapter 1, I investigate the role of heterogeneous landscapes and its effects on the population structure and dynamics of small mammals. Theory provides several models, including ideal free distribution and source-sink dynamics, to predict how individuals may respond to ...
Wildlife Research Monographs, 2016
Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands... more Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands of years, beginning some 1.8 million years ago, and until the Neolithic Revolution (some 10,000 years ago), when agriculture gradually spread through human societies (Marlowe 2005 ). Hunter-gatherer societies obtained their food directly from “natural” ecosystems, by hunting wild animals and collecting wild plants (Richerson et al. 1996 ). Early agrarian societies started planting desired crops on suitable lands, competing with wildlife for space and resources. As agrarian societies evolved, techniques for planting and harvesting became technologically more advanced and more efficient (Richerson et al. 1996 ). Innovations thus allowed the human population to grow and to colonize nearly every terrestrial ecosystem type on Earth.
Tree Islands of the Everglades, 2002
Chapter 14 Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in t... more Chapter 14 Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in the Everglades Michael S. Gaines1, Christopher R. Sasso1, James E. Diffendorfer2, and Harald Beck1 'University of Miami, Department of Biology, Coral Gables, FL 33124. 2San Diego ...
Journal of Mammalogy, 2011
... Seventeen skull measurements were used for the morphological characterization, and from these... more ... Seventeen skull measurements were used for the morphological characterization, and from these, indexes were obtained for the functional analysis of bite performance (temporal and masseter muscular systems) and head elevation (semispinalis capitis/complexus muscular ...
Biological Conservation, 2013
ABSTRACT “Empty forests” in which humans have driven large vertebrate species to extinction lack ... more ABSTRACT “Empty forests” in which humans have driven large vertebrate species to extinction lack myriad direct and indirect species interactions. This may alter key ecosystem processes, including trophic cascades, disturbance regimes, and nutrient cycling. Past research concerning the effects of tropical forest defaunation mainly compared sites with an intact fauna with sites having degraded faunal communities. However, experimental studies on seedling demographics at individual sites, with the same abiotic and biotic conditions, over a long period of time are still scarce. In this research we conducted a 7-year experiment within a completely intact and pristine forest in Manu National Park, Peru to elucidate the effects of defaunation on tree seedling demographics and densities. We constructed semipermeable exclosures that prevented access of large terrestrial vertebrates, but allowed free passage of small- and medium-sized species. New tree seedlings taller than 5 cm were tagged and followed. Jolly–Seber mark-recapture models were used to estimate density, survival, and recruitment of seedlings. Seedling density in the exclosures continued to increase significantly after the first year of the study. Only during the first 2 years was seedling survival higher in the exclosures. The numbers of new recruits were consistently higher in exclosures when compared to open control plots throughout the study. In accord with increased density, survival, and recruitment in exclosure plots, we also observed increased understory vegetation cover. Our results suggest that defaunation can have long-term effects on seedling demographics and density, which could ultimately influence the composition and diversity of the canopy tree community.
Seed fate: predation, dispersal and seedling establishment, Mar 31, 2005
Studies on plant-frugivore interactions are crucial for the understanding of evolutionary and eco... more Studies on plant-frugivore interactions are crucial for the understanding of evolutionary and ecological processes at species, population, and community levels. These interactions are more complex in the tropics than in other ecosystems because of their higher species richness of both frugivores and plants. A comprehensive understanding of these processes, plus the development of new hypotheses and future research can only be achieved if ecologists consider existing results and examine interactions among many different taxa. ...
Handchirurgie · Mikrochirurgie · Plastische Chirurgie
The goal of the presented carpal tunnel syndrome (CTS) follow-up study was to compare the clinica... more The goal of the presented carpal tunnel syndrome (CTS) follow-up study was to compare the clinical value of the Millesi hand function score with the "Pressure Specifying Sensory Device" (PSSD) introduced by A. L. Dellon using self-administered patient questionnaires. 25 patients (10 male, 15 female) with an electrodiagnostically confirmed CTS were enrolled in this study, performing one preoperative and five postoperative examinations over 24 weeks. 12 of the 25 patients underwent an "open" two-portal carpal tunnel release with two minimal incisions (group OT); the other 13 patients were treated with a two-portal endoscopic carpal tunnel release (group ET). Additionally, in eleven out of the twelve patients of group OT, an epineuriotomy of the median nerve was performed during the same session. Concerning preoperative data of the Millesi score and the PSSD, no statistically significant differences were found between group OT and ET. However, preoperative compariso...
Plastic and Reconstructive Surgery, 2009
ABSTRACT An abstract is unavailable. This article is available as HTML full text and PDF.
Because of their range expansion across North America, coyotes (Canis latrans) now occur sympatri... more Because of their range expansion across North America, coyotes (Canis latrans) now occur sympatrically with numerous other predator species, including red foxes (Vulpes vulpes). This raises several interesting ecological questions, including if and how sympatry affects the diet and gut microbiomes of coyotes and red foxes. We examined the gut microbiomes of sympatric populations of coyotes and red foxes within two different National Parks in Virginia, USA, that differ in land use, vegetation, and anthropogenic disturbance: Prince William Forest Park (PRWI) and Manassas National Battlefield Park (MANA). From 2012 to 2017, scat samples from PRWI and MANA were collected and analyzed. Polymerase Chain Reaction (PCR) amplification of a region of the mitochondrial cytochrome-b gene followed by restriction enzyme digestion of the PCR product was used to determine the origin of each scat sample. Next-Generation DNA sequencing of a hypervariable 16S rRNA gene region was used to determine gut...
Journal of Tropical Ecology, Aug 31, 2007
Most seedlings and saplings remain in the forest understorey for decades before becoming adults o... more Most seedlings and saplings remain in the forest understorey for decades before becoming adults or dying, and thus may be exposed to various sources of physical disturbance (Clark & Clark 1991, 2001). Because tree species vary in their ability to recover after physical damage (Gillman et al. 2003, Guariguata 1998), this damage can act as an ecological filter and influence the juvenile community structure and species composition (Peters et al. 2004). Studies have demonstrated the occurrence and magnitude of stem breakage in juveniles caused by falling branches and other canopy debris (Clark & Clark 1989, 1991; Gillman & Ogden 2001, Scariot 2000). Surprisingly, little is known about the magnitude and ecological consequences of physical damage to juvenile plants by mammals, particularly large ungulates, including herbivory, trampling and uprooting (Gillman & Ogden 2003, Roldán & Simonetti 2001).
In chapter 1, I investigate the role of heterogeneous landscapes and its effects on the populatio... more In chapter 1, I investigate the role of heterogeneous landscapes and its effects on the population structure and dynamics of small mammals. Theory provides several models, including ideal free distribution and source-sink dynamics, to predict how individuals may respond to ...
Wildlife Research Monographs, 2016
Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands... more Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands of years, beginning some 1.8 million years ago, and until the Neolithic Revolution (some 10,000 years ago), when agriculture gradually spread through human societies (Marlowe 2005 ). Hunter-gatherer societies obtained their food directly from “natural” ecosystems, by hunting wild animals and collecting wild plants (Richerson et al. 1996 ). Early agrarian societies started planting desired crops on suitable lands, competing with wildlife for space and resources. As agrarian societies evolved, techniques for planting and harvesting became technologically more advanced and more efficient (Richerson et al. 1996 ). Innovations thus allowed the human population to grow and to colonize nearly every terrestrial ecosystem type on Earth.
Tree Islands of the Everglades, 2002
Chapter 14 Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in t... more Chapter 14 Effects of Tree Island Size and Water on the Population Dynamics of Small Mammals in the Everglades Michael S. Gaines1, Christopher R. Sasso1, James E. Diffendorfer2, and Harald Beck1 'University of Miami, Department of Biology, Coral Gables, FL 33124. 2San Diego ...
Journal of Mammalogy, 2011
... Seventeen skull measurements were used for the morphological characterization, and from these... more ... Seventeen skull measurements were used for the morphological characterization, and from these, indexes were obtained for the functional analysis of bite performance (temporal and masseter muscular systems) and head elevation (semispinalis capitis/complexus muscular ...
Biological Conservation, 2013
ABSTRACT “Empty forests” in which humans have driven large vertebrate species to extinction lack ... more ABSTRACT “Empty forests” in which humans have driven large vertebrate species to extinction lack myriad direct and indirect species interactions. This may alter key ecosystem processes, including trophic cascades, disturbance regimes, and nutrient cycling. Past research concerning the effects of tropical forest defaunation mainly compared sites with an intact fauna with sites having degraded faunal communities. However, experimental studies on seedling demographics at individual sites, with the same abiotic and biotic conditions, over a long period of time are still scarce. In this research we conducted a 7-year experiment within a completely intact and pristine forest in Manu National Park, Peru to elucidate the effects of defaunation on tree seedling demographics and densities. We constructed semipermeable exclosures that prevented access of large terrestrial vertebrates, but allowed free passage of small- and medium-sized species. New tree seedlings taller than 5 cm were tagged and followed. Jolly–Seber mark-recapture models were used to estimate density, survival, and recruitment of seedlings. Seedling density in the exclosures continued to increase significantly after the first year of the study. Only during the first 2 years was seedling survival higher in the exclosures. The numbers of new recruits were consistently higher in exclosures when compared to open control plots throughout the study. In accord with increased density, survival, and recruitment in exclosure plots, we also observed increased understory vegetation cover. Our results suggest that defaunation can have long-term effects on seedling demographics and density, which could ultimately influence the composition and diversity of the canopy tree community.
Seed fate: predation, dispersal and seedling establishment, Mar 31, 2005
Studies on plant-frugivore interactions are crucial for the understanding of evolutionary and eco... more Studies on plant-frugivore interactions are crucial for the understanding of evolutionary and ecological processes at species, population, and community levels. These interactions are more complex in the tropics than in other ecosystems because of their higher species richness of both frugivores and plants. A comprehensive understanding of these processes, plus the development of new hypotheses and future research can only be achieved if ecologists consider existing results and examine interactions among many different taxa. ...
Handchirurgie · Mikrochirurgie · Plastische Chirurgie
The goal of the presented carpal tunnel syndrome (CTS) follow-up study was to compare the clinica... more The goal of the presented carpal tunnel syndrome (CTS) follow-up study was to compare the clinical value of the Millesi hand function score with the "Pressure Specifying Sensory Device" (PSSD) introduced by A. L. Dellon using self-administered patient questionnaires. 25 patients (10 male, 15 female) with an electrodiagnostically confirmed CTS were enrolled in this study, performing one preoperative and five postoperative examinations over 24 weeks. 12 of the 25 patients underwent an "open" two-portal carpal tunnel release with two minimal incisions (group OT); the other 13 patients were treated with a two-portal endoscopic carpal tunnel release (group ET). Additionally, in eleven out of the twelve patients of group OT, an epineuriotomy of the median nerve was performed during the same session. Concerning preoperative data of the Millesi score and the PSSD, no statistically significant differences were found between group OT and ET. However, preoperative compariso...
Plastic and Reconstructive Surgery, 2009
ABSTRACT An abstract is unavailable. This article is available as HTML full text and PDF.
Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands... more Hunting and gathering remained the main mode of subsistence of humanity for hundreds of thousands of years, beginning some 1.8 million years ago, and until the Neolithic Revolution (some 10,000 years ago), when agriculture gradually spread through human societies (Marlowe 2005 ). Hunter-gatherer societies obtained their
food directly from “natural” ecosystems, by hunting wild animals and collecting wild plants (Richerson et al. 1996 ). Early agrarian societies started planting desired crops on suitable lands, competing with wildlife for space and resources. As agrarian societies evolved, techniques for planting and harvesting became technologically more advanced and more efficient (Richerson et al. 1996 ). Innovations thus allowed the human population to grow and to colonize nearly every terrestrial ecosystem type on Earth.
Natural disturbances such as treefalls are a major component of tropical forest dynamics. These o... more Natural disturbances such as treefalls are a major component of tropical forest dynamics. These omnipresent treefall gaps are crucial for forest regeneration and promote plant diversity. However the effects of treefalls on mammals are not well understood. This book provides novel insights into the population dynamics, community structure, and species richness of terrestrial and arboreal small mammals in treefall gaps and undisturbed forests within the Amazonas. The discovery of a reciprocal source-sink dynamics and the underlying mechanisms of higher mammalian species diversity in gaps contributes to a better understanding of the role of natural disturbances. This book will be especial useful for biology students and professionals interested in tropical ecology and new strategies for conservation and forest management.
RESUMEN EJECUTIVO Este informe contiene una evaluación del estado a nivel de la distribución de ... more RESUMEN EJECUTIVO
Este informe contiene una evaluación del estado a nivel de la distribución de dos de las especies de mamíferos ecológica y económicamente más importantes del Neotrópico. El pecarí labiado (Tayassu pecari) y el tapir de tierras bajas (Tapirus terrestris) tienen áreas de distribución enormes; el primero se extiende a lo largo de hábitats tropicales y subtropicales desde el sur de México hasta el norte de Argentina, mientras que el segundo comparte la misma distribución pero en la porción sudamericana. Estas especies son arquitectas de los ecosistemas cumpliendo roles vitales en la estructuración de
las comunidades vegetales. Ambas especies han sido fuentes clave de alimento para cazadores de subsistencia en toda la región y el tráfico internacional de productos de los pecaríes ha sido también económicamente significativo, aunque resultando en una amenaza para la especie donde la cosecha
no es sustentable. Como resultado de la cacería excesiva y la destrucción de sus hábitats, ambas especies son consideradas en peligro o amenazadas en varios países y están incluidas en el Apéndice II de la CITES (Convención sobre el Comercio de Especies Amenazadas de Fauna y Flora Silvestres).
Este trabajo ofrece información para la planificación de la conservación y una línea de base para evaluar cambios futuros en el estado y distribución de estas dos especies. También da una indicación de la salud de los ecosistemas a lo largo de su distribución, ya que ambas especies son muy
susceptibles a la presión humana y resultan útiles para el seguimiento o monitoreo del estado de conservación de sus hábitats. Para llevar a cabo este trabajo, muchos rofesionales de 14 países del Neotrópico que estudian los tapires y los pecaríes aportaron datos y contribuyeron al análisis y conclusiones. A continuación se presentan los resultados más sobresalientes.