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1.
Biol Lett ; 19(10): 20230202, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37817576

RESUMEN

Animals are faced with a variety of dangers or threats, which are increasing in frequency with ongoing environmental change. While our understanding of fearfulness of such dangers is growing in the context of predation and parasitism risk, the extent to which non-trophic, interspecific dangers elicit fear in animals remains less appreciated. We provide an experimental test for fear responses of savannah ungulates to a dominant and aggressive megaherbivore, the African bush elephant (Loxodonta africana), and contrast responses to an apex predator known to elicit fear in this system. Using an automated behavioural response system, we contrast vigilance and run responses of ungulates to elephant, leopard (Panthera pardus), and control (red-chested cuckoo Cuculus solitarius) vocalizations. Overall, we find that ungulates responded to elephant calls, both in terms of an increase in run and vigilance responses relative to controls. The magnitude of most behavioural responses (four of six considered) to elephant vocalizations were not significantly different than responses to leopards. These results suggest that megaherbivores can elicit strong non-trophic fear responses by ungulates and call to broaden frameworks on fear to consider dominant species, such as megaherbivores, as key modifiers of fear-induced interactions.


Asunto(s)
Elefantes , Animales , Elefantes/fisiología , Mamíferos , Conducta Predatoria , Miedo , Agresión , Aves
2.
Oecologia ; 201(3): 661-671, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36897410

RESUMEN

The decline of terrestrial predator populations across the globe is altering top-down pressures that drive predator-prey interactions. However, a knowledge gap remains in understanding how removing terrestrial predators affects prey behavior. Using a bifactorial playback experiment, we exposed fox squirrels to predator (red-tailed hawks, coyotes, dogs) and non-predator control (Carolina wren) calls inside terrestrial predator exclosures, accessible to avian predators, and in control areas subject to ambient predation risk. Fox squirrels increased their use of terrestrial predator exclosures, a pattern that corresponded with 3 years of camera trapping. Our findings suggest fox squirrels recognized that exclosures had predictably lower predation risk. However, exclosures had no effect on their immediate behavioral response towards any call, and fox squirrels responded most severely to hawk predator calls. This study shows that anthropogenically driven predator loss creates predictably safer areas (refugia) that prey respond to proactively with increased use. However, the persistence of a lethal avian predator is sufficient to retain a reactive antipredator response towards an immediate predation threat. Some prey may benefit from shifting predator-prey interactions by gaining refugia without sacrificing a sufficient response towards potential predators.


Asunto(s)
Sciuridae , Pájaros Cantores , Animales , Perros , Conducta Predatoria , Dinámica Poblacional
3.
Proc Natl Acad Sci U S A ; 117(36): 22274-22280, 2020 09 08.
Artículo en Inglés | MEDLINE | ID: mdl-32848069

RESUMEN

Connectivity has long played a central role in ecological and evolutionary theory and is increasingly emphasized for conserving biodiversity. Nonetheless, connectivity assessments often focus on individual species even though understanding and preserving connectivity for entire communities is urgently needed. Here we derive and test a framework that harnesses the well-known allometric scaling of animal movement to predict community-level connectivity across protected area networks. We used a field translocation experiment involving 39 species of southern African birds to quantify movement capacity, scaled this relationship to realized dispersal distances determined from ring-and-recovery banding data, and used allometric scaling equations to quantify community-level connectivity based on multilayer network theory. The translocation experiment explained observed dispersal distances from ring-recovery data and emphasized allometric scaling of dispersal based on morphology. Our community-level networks predicted that larger-bodied species had a relatively high potential for connectivity, while small-bodied species had lower connectivity. These community networks explained substantial variation in observed bird diversity across protected areas. Our results highlight that harnessing allometric scaling can be an effective way of determining large-scale community connectivity. We argue that this trait-based framework founded on allometric scaling provides a means to predict connectivity for entire communities, which can foster empirical tests of community theory and contribute to biodiversity conservation strategies aimed at mitigating the effects of environmental change.


Asunto(s)
Distribución Animal , Aves/fisiología , Ecosistema , Modelos Biológicos , Animales
4.
Proc Biol Sci ; 282(1805)2015 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-25788598

RESUMEN

To address the ongoing debate over the impact of invasive species on native terrestrial wildlife, we conducted a large-scale experiment to test the hypothesis that invasive Burmese pythons (Python molurus bivittatus) were a cause of the precipitous decline of mammals in Everglades National Park (ENP). Evidence linking pythons to mammal declines has been indirect and there are reasons to question whether pythons, or any predator, could have caused the precipitous declines seen across a range of mammalian functional groups. Experimentally manipulating marsh rabbits, we found that pythons accounted for 77% of rabbit mortalities within 11 months of their translocation to ENP and that python predation appeared to preclude the persistence of rabbit populations in ENP. On control sites, outside of the park, no rabbits were killed by pythons and 71% of attributable marsh rabbit mortalities were classified as mammal predations. Burmese pythons pose a serious threat to the faunal communities and ecological functioning of the Greater Everglades Ecosystem, which will probably spread as python populations expand their range.


Asunto(s)
Boidae/fisiología , Cadena Alimentaria , Especies Introducidas , Lagomorpha/fisiología , Animales , Conservación de los Recursos Naturales , Florida , Dinámica Poblacional
5.
PeerJ ; 12: e17577, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38938602

RESUMEN

Background: Enhancing detection of cryptic snakes is critical for the development of conservation and management strategies; yet, finding methods that provide adequate detection remains challenging. Issues with detecting snakes can be particularly problematic for some species, like the invasive Burmese python (Python bivittatus) in the Florida Everglades. Methods: Using multiple survey methods, we predicted that our ability to detect pythons, larger snakes and all other snakes would be enhanced with the use of live mammalian lures (domesticated rabbits; Oryctolagus cuniculus). Specifically, we used visual surveys, python detection dogs, and time-lapse game cameras to determine if domesticated rabbits were an effective lure. Results: Time-lapse game cameras detected almost 40 times more snakes (n = 375, treatment = 245, control = 130) than visual surveys (n = 10). We recorded 21 independent detections of pythons at treatment pens (with lures) and one detection at a control pen (without lures). In addition, we found larger snakes, and all other snakes were 165% and 74% more likely to be detected at treatment pens compared to control pens, respectively. Time-lapse cameras detected almost 40 times more snakes than visual surveys; we did not detect any pythons with python detection dogs. Conclusions: Our study presents compelling evidence that the detection of snakes is improved by coupling live mammalian lures with time-lapse game cameras. Although the identification of smaller snake species was limited, this was due to pixel resolution, which could be improved by changing the camera focal length. For larger snakes with individually distinctive patterns, this method could potentially be used to identify unique individuals and thus allow researchers to estimate population dynamics.


Asunto(s)
Boidae , Serpientes , Imagen de Lapso de Tiempo , Animales , Conejos , Imagen de Lapso de Tiempo/métodos , Florida , Perros , Fotograbar/instrumentación , Fotograbar/métodos , Conducta Predatoria/fisiología
6.
Sci Rep ; 14(1): 19668, 2024 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-39181911

RESUMEN

Mid-sized mammals (i.e., mesomammals) fulfill important ecological roles, serving as essential scavengers, predators, pollinators, and seed dispersers in the ecosystems they inhabit. Consequently, declines in mesomammal populations have the potential to alter ecological processes and fundamentally change ecosystems. However, ecosystems characterized by high functional redundancy, where multiple species can fulfil similar ecological roles, may be less impacted by the loss of mesomammals and other vertebrates. The Greater Everglades Ecosystem in southern Florida is a historically biodiverse region that has recently been impacted by multiple anthropogenic threats, most notably the introduction of the Burmese python (Python molurus bivittatus). Since pythons became established, mesomammal populations have become greatly reduced. To assess whether these declines in mesomammals have affected two critical ecosystem functions-scavenging and frugivory-we conducted experiments in areas where mesomammals were present and absent. We did not observe significant differences in scavenging or frugivory efficiency in areas with and without mesomammals, but we did observe significant differences in the communities responsible for scavenging and frugivory. Despite the observed evidence of redundancy, the changes in community composition could potentially lead to indirect consequences on processes like seed dispersal and disease dynamics within this ecosystem, emphasizing the need for further study.


Asunto(s)
Ecosistema , Animales , Florida , Boidae/fisiología , Mamíferos/fisiología , Dinámica Poblacional , Dispersión de Semillas/fisiología , Especies Introducidas
7.
Appl Environ Microbiol ; 79(18): 5465-71, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23811520

RESUMEN

Since 2006, Geomyces destructans, the causative agent of white nose syndrome (WNS), has killed over 5.7 million bats in North America. The current hypothesis suggests that this novel fungus is an invasive species from Europe, but little is known about the diversity within the genus Geomyces and its distribution on bats in the United States. We documented the psychrophilic and psychrotolerant fungal flora of hibernating bats prior to the arrival of WNS using culture-based techniques. A total of 149 cultures, which were obtained from 30 bats in five bat hibernacula located in four caves and one mine, were sequenced for the entire internal transcribed spacer (ITS) nuclear ribosomal DNA (nrDNA) region. Approximately 53 operational taxonomic units (OTUs) at 97% similarity were recovered from bat wings, with the community dominated by fungi within the genera Cladosporium, Fusarium, Geomyces, Mortierella, Penicillium, and Trichosporon. Eleven Geomyces isolates were obtained and placed in at least seven distinct Geomyces clades based on maximum-likelihood phylogenetic analyses. Temperature experiments revealed that all Geomyces strains isolated are psychrotolerant, unlike G. destructans, which is a true psychrophile. Our results confirm that a large diversity of fungi, including several Geomyces isolates, occurs on bats prior to the arrival of WNS. Most of these isolates were obtained from damaged wings. Additional studies need to be conducted to determine potential ecological roles of these abundant Geomyces strains isolated from bats.


Asunto(s)
Biodiversidad , Quirópteros/microbiología , Hongos/clasificación , Hongos/aislamiento & purificación , Estrés Fisiológico , Alas de Animales/microbiología , Animales , Análisis por Conglomerados , Frío , ADN de Hongos/química , ADN de Hongos/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Hongos/genética , Hongos/efectos de la radiación , Datos de Secuencia Molecular , Filogenia , Análisis de Secuencia de ADN , Estados Unidos
8.
Sci Rep ; 13(1): 7619, 2023 05 10.
Artículo en Inglés | MEDLINE | ID: mdl-37165034

RESUMEN

To understand how two dominant African savanna trees will continue to respond to climate changes, we examined their regeneration niche and adult tree distributions. Specifically, we wanted to (1) determine if distributional patterns were shifting, (2) predict future distributions under different climate change scenarios and (3) evaluate the realism of predicted future distributions. We randomly placed 40 grids into 6 strata across a climate gradient in the kingdom of Eswatini. Within these grids, we sampled adult and seedling marula (Scelerocarya birrea) and knobthorn (Senegalia nigrecens) trees and used the data to model their abundance. Next, we quantified shifts in distributional patterns (e.g., expansion or contraction) by measuring the current and projected areas of overlap between seedling and adult trees. Finally, we predicted future distributions of abundance based on predicted climate conditions. We found knobthorn seedlings within a small portion of the adult distribution, suggesting it was unlikely to track climate changes. Alternatively, finding marula seedlings on and beyond one edge of the adult distribution, suggested its range would shift toward cooler climates. Predicted future distributions suggest suitable climate for both species would transition out of savannas and into grasslands. Future projections (2041-2070) appeared consistent with observed distributions of marula, but knobthorn predictions were unrealistic given the lack of evidence for regeneration outside of its current range. The idiosyncratic responses of these species to climate change are likely to decouple these keystone structures in the coming decades and are likely to have considerable cascading effects including the potential rearrangement of faunal communities.


Asunto(s)
Pradera , Árboles , Cambio Climático , Plantones , Predicción , Ecosistema
9.
Animals (Basel) ; 13(5)2023 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-36899806

RESUMEN

Increasing human-bear conflicts are a growing concern, and managers often assume bears in developed areas are food-conditioned. We examined the relationship between human-bear conflicts and food conditioning by analyzing isotopic values of hair from black bears (Ursus americanus floridanus) involved in research (n = 34) and conflicts (n = 45). We separated research bears into wild and developed subgroups based on the impervious surface within their home ranges and separated conflict bears based on observations of human food consumption (anthropogenic = observations; management = no observations). We initially assumed wild bears were not food conditioned and anthropogenic bears were. However, using isotopic values, we classified 79% of anthropogenic bears and 8% of wild bears as food conditioned. Next, we assigned these bears to the appropriate food conditioned category and used the categorizations as a training set to classify developed and management bears. We estimated that 53% of management bears and 20% of developed bears were food conditioned. Only 60% of bears captured within or using developed areas showed evidence of food conditioning. We also found that δ13C values were a better predictor of anthropogenic foods in a bear's diet than δ15N values. Our results indicate that bears in developed areas are not necessarily food conditioned and caution against management actions based on limited observations of bear behavior.

10.
Trends Ecol Evol ; 38(10): 970-979, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37330409

RESUMEN

Many ecologists increasingly advocate for research frameworks centered on the use of 'big data' to address anthropogenic impacts on ecosystems. Yet, experiments are often considered essential for identifying mechanisms and informing conservation interventions. We highlight the complementarity of these research frameworks and expose largely untapped opportunities for combining them to speed advancements in ecology and conservation. With nascent but increasing application of model integration, we argue that there is an urgent need to unite experimental and big data frameworks throughout the scientific process. Such an integrated framework offers potential for capitalizing on the benefits of both frameworks to gain rapid and reliable answers to ecological challenges.


Asunto(s)
Ecología , Ecosistema , Conservación de los Recursos Naturales
11.
J Occup Environ Hyg ; 8(2): 113-22, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21253984

RESUMEN

In 2001, letters filled with a powder containing anthrax (Bacillus anthracis) spores were delivered by mail to a number of governmental and media locations within the United States. In response, the U.S. Centers for Disease Control and Prevention (CDC) provided guidelines for office personnel who might encounter a letter containing suspicious powder. These guidelines were developed during the crisis and in the absence of experimental data from laboratory or field investigations. An obvious need thus exists for quantitative and scientific verification for validation of these guidelines. This study attempts to address this need, adapting earlier work that used a multiple small office test site to create a model system in an open office test site in a vacated office building in which Bacillus atrophaeus spores (as a simulant for B. anthracis spores) were released by opening a letter. Using SF(6) as a tracer gas, smoke tubes (containing stannic chloride) to visualize airflow, culturable aerosol sampling, and aerosol spectrometry we were able to characterize airflow and unmitigated spore aerosol dissemination within the office test site. Subsequently, two scripted test scenarios were used to reproduce selected portions of the existing CDC response guidelines and a modified version where the contaminated letter opener warned co-workers to evacuate then waited 5 min before doing so himself. By not leaving together with other co-workers, the risk of the letter opener cross-contaminating others was eliminated. The total potential spore aerosol exposure of the letter opener was not affected by remaining still and waiting 5 min to allow co-workers to escape first before leaving the office. Closing office doors and quickly deactivating the heating, ventilation, and air conditioning system significantly reduced spore aerosol concentrations outside the main open office in which they had been released.


Asunto(s)
Bacillus anthracis , Bioterrorismo , Centers for Disease Control and Prevention, U.S./normas , Guías como Asunto , Servicios Postales/métodos , Movimientos del Aire , Humanos , Exposición Profesional/prevención & control , Polvos , Estados Unidos
12.
Sci Rep ; 11(1): 12979, 2021 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-34155290

RESUMEN

The fear large carnivores inspire in large ungulates has been argued to have cascading effects down food webs. However, a direct link between ungulate habitat use and their fear of large carnivores has not been experimentally tested. To fill this critical gap, we conducted a bi-factorial experiment in an African savanna. We removed shrub cover and broadcast large carnivore vocalizations (leopard, hyena, dog) or non-threatening control vocalizations in both experimentally cleared and shrubby control sites. We recorded the proactive (frequency of visitation) and reactive (fleeing or vigilance) responses of multiple prey (impala, warthog, nyala and bushbuck). Critically, we found a significant proactive-reactive interaction. Ungulates were 47% more likely to run after hearing a predator vocalization in shrubby control sites than experimental clearings, demonstrating that ungulates perceived less fear from large carnivores in open habitat (clearings). Consistent with this finding, ungulates visited clearings 2.4 times more often than shrubby control sites and visited shrubby control sites less often at night, when large carnivores are most active. Combined with results from previous experiments demonstrating that the disproportionate use of available habitats by large ungulates can alter ecosystem properties, our experiment provides critical evidence that the fear large carnivores inspire in large ungulates can cause trophic cascades.


Asunto(s)
Conducta Animal , Carnívoros , Ecosistema , Miedo , Animales , Cadena Alimentaria , Conducta Predatoria , Vocalización Animal
13.
Estuaries Coast ; 44(4): 899-910, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33100935

RESUMEN

Climate change will alter natural areas on a global scale within the next century. In areas vulnerable to climate change, scientists are regularly challenged to justify the resources needed for research and conservation. We face what may seem like a losing battle, especially in low-lying coastal areas where sea-level rise is predicted to severely degrade or destroy many ecosystems. Using sea-level rise in the low-elevation state of Florida, USA, as a case study, we argue that it is critical to remain engaged in the research, restoration, and conservation of natural areas threatened by climate change for as long as possible. These areas will continue to provide invaluable ecological and societal benefits. Additionally, uncertainty surrounding climate change forecasts and their ecological impact leaves room for optimism, research, and actions that are necessary for developing adaptation plans and mitigating further sea-level rise and other consequences of climate change. We urge scientists and particularly students beginning their careers not to forego research and conservation efforts of these imperiled lands but to face this unprecedented challenge with determination, creativity, and solution-based strategies.

14.
Heliyon ; 7(3): e06563, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33851055

RESUMEN

Agricultural intensification is a threat to terrestrial ecosystems around the world. Agricultural areas, especially monocultures, create homogenous landscapes for wildlife. However, certain crops, such as sugarcane, are harvested in phases, creating a mosaic of fields in different stages of growth. We investigated changes in avian communities across four different sugarcane growth stages: emerging, short, medium and tall sugarcane, as well as control sites that represented native savanna habitat in northeast Eswatini prior to conversion to agriculture. In total, we sampled nine sites in sugarcane fields (at different growth stages) and three in native savanna. We conducted bird counts at 5-week intervals along 200m line transects over both the breeding and non-breeding seasons. We recorded a total of 124 bird species belonging to 58 families. Bird species richness and diversity were higher in savannas compared to any stages of growth in sugarcane. In contrast, functional beta diversity and uniqueness were higher in sugarcane than in savanna. Community composition was also different between the two land-uses. While there was overlap in bird species composition between different sugarcane growth stages, there was high beta diversity and high turnover between sites, indicative of the high temporal and spatial variability in bird communities in sugarcane fields. We demonstrated that the spatial and temporal variability created by the different growth stages of sugarcane promotes the occurrence of species with different traits, which may contribute to ecosystem functioning and promote the conservation of bird species as sugarcane fields can provide resource complementation for species with different needs.

15.
Ecohealth ; 18(4): 421-428, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34970712

RESUMEN

We investigated the prevalence of coronaviruses in 44 bats from four families in northeastern Eswatini using high-throughput sequencing of fecal samples. We found evidence of coronaviruses in 18% of the bats. We recovered full or near-full-length genomes from two bat species: Chaerephon pumilus and Afronycteris nana, as well as additional coronavirus genome fragments from C. pumilus, Epomophorus wahlbergi, Mops condylurus, and Scotophilus dinganii. All bats from which we detected coronaviruses were captured leaving buildings or near human settlements, demonstrating the importance of continued surveillance of coronaviruses in bats to better understand the prevalence, diversity, and potential risks for spillover.


Asunto(s)
Quirópteros , Infecciones por Coronavirus , Coronavirus , Metagenómica , Animales , Quirópteros/virología , Coronavirus/genética , Infecciones por Coronavirus/veterinaria , Esuatini , Variación Genética , Genoma Viral , Filogenia
16.
Commun Biol ; 4(1): 804, 2021 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-34183751

RESUMEN

The composition of wildlife communities can have strong effects on transmission of zoonotic vector-borne pathogens, with more diverse communities often supporting lower infection prevalence in vectors (dilution effect). The introduced Burmese python, Python bivittatus, is eliminating large and medium-sized mammals throughout southern Florida, USA, impacting local communities and the ecology of zoonotic pathogens. We investigated invasive predator-mediated impacts on ecology of Everglades virus (EVEV), a zoonotic pathogen endemic to Florida that circulates in mosquito-rodent cycle. Using binomial generalized linear mixed effects models of field data at areas of high and low python densities, we show that increasing diversity of dilution host (non-rodent mammals) is associated with decreasing blood meals on amplifying hosts (cotton rats), and that increasing cotton rat host use is associated with increasing EVEV infection in vector mosquitoes. The Burmese python has caused a dramatic decrease in mammal diversity in southern Florida, which has shifted vector host use towards EVEV amplifying hosts (rodents), resulting in an indirect increase in EVEV infection prevalence in vector mosquitoes, putatively elevating human transmission risk. Our results indicate that an invasive predator can impact wildlife communities in ways that indirectly affect human health, highlighting the need for conserving biological diversity and natural communities.


Asunto(s)
Boidae/fisiología , Culex/virología , Virus de la Encefalitis Equina Venezolana/aislamiento & purificación , Interacciones Huésped-Patógeno , Especies Introducidas , Mosquitos Vectores/virología , Zoonosis Virales/transmisión , Animales , Ecosistema , Femenino , Cadena Alimentaria , Humanos
17.
Ecol Evol ; 10(22): 12613-12619, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33250997

RESUMEN

Field-based course work has been foundational to Ecology and Evolutionary Biology curricula. However, opportunities for these experiences gradually have decreased over the past few decades and are being replaced with technology in the college learning environment. The coronavirus disease 2019 pandemic facilitated a rapid transition of all field-based courses to online only delivery, which we argue has forced us to reconsider how to deliver course content to retain field experiences in a manner that is safe during the pandemic but robust to ever changing constraints in the college classroom. Here, we propose pairing an intensive laboratory experience with an otherwise online delivery. We discuss several advantages of intensive laboratory experiences that occur in the field over a short but intensive time period over that of the traditional low-intensity weekly laboratory structure. In particular, intensive laboratory experiences are safer during the pandemic because they allow the group to be tested and isolated, allow more flexibility for students with competing interests for their time, and also enhance student interpersonal skills while still providing strong reinforcement of the skills typically honed through experiential learning. We present case studies for how we intend to apply our proposed model to two courses that heavily rely on field-based experiential learning to facilitate adoption.

18.
Int J Parasitol Parasites Wildl ; 13: 62-71, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-32884900

RESUMEN

Infectious diseases vary in prevalence and pathology among host species. Species may differ in prevalence of infection due to varying exposure and susceptibility to disease agents throughout their lifetime, which may be attributable to underlying differences in their phenology, physiology and behavior. A recently growing body of literature has focused on the utility of host life-history traits to provide mechanistic explanations for interspecific variation in host-parasite associations. In this study, we utilized diverse avian and haemosporidian assemblages in an African savanna to evaluate the link between haemosporidia prevalence (Plasmodium, Haemoproteus, Leucocytozoon) and avian life-history traits such as body size, mating system, nest care and nest structure. We found that variation of haemosporidia prevalence was consistent with life-history traits that pertain to the reproduction of avian host. Nest care was the single most important predictor of infection status. In birds with shared and female-only nest care, the expected rates of parasitism were between 8- and 12-fold higher than in avian brood parasites that provide no nest care. This finding supports the hypothesis that parental care is an evolutionarily costly life-history trait that increases species' risk of infection with vector-borne diseases. The influence of other host traits (nest structure, body size) was less consistent suggesting that differences in the vectors' ecology and host-seeking behavior produce variable patterns of parasitism among haemosporidia genera. Nest structure influenced infection with Haemoproteus and Leucocytozoon only. Leucocytozoon infections were associated with ground-nesting birds, while Haemoproteus infections were associated with birds that build open nest structures. Body size was an important predictor of Leucocytozoon infections, particularly large-bodied birds like guineafowl and doves, which exhibited high prevalences.

19.
Curr Zool ; 66(6): 601-606, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33391358

RESUMEN

An animal's pelage, feather, or skin color can serve a variety of functions, so it is important to have multiple standardized methods for measuring color. One of the most common and reliable methods for measuring animal coloration is the use of standardized digital photographs of animals. New technology in the form of a commercially available handheld digital color sensor could provide an alternative to photography-based animal color measurements. To determine whether a digital color sensor could be used to measure animal coloration, we tested the ability of a digital color sensor to measure coloration of mammalian, avian, and lepidopteran museums specimens. We compared results from the sensor to measurements taken using traditional photography methods. Our study yielded significant differences between photography-based and digital color sensor measurements of brightness (light to dark) and colors along the green to red spectrum. There was no difference between photographs and the digital color sensor measurements for colors along the blue to yellow spectrum. The average difference in recorded color (ΔE) by the 2 methods was above the threshold at which humans can perceive a difference. There were significant correlations between the sensor and photographs for all measurements indicating that the sensor is an effective animal coloration measuring tool. However, the sensor's small aperture and narrow light spectrum range designed for human-vision limit its value for ecological research. We discuss the conditions in which a digital color sensor can be an effective tool for measuring animal coloration in both laboratory settings and in the field.

20.
Artículo en Inglés | MEDLINE | ID: mdl-31652699

RESUMEN

Globally, communities are increasingly impacted by the stressors of climate change. In response, people may adapt to maintain their livelihoods and overall health and nutrition. However, the relationship between climate adaptation and human nutrition is poorly understood and results of adaptation are often unclear. We investigated the relationship between adaptation and child nutrition, in Eswatini (formerly Swaziland) during an extreme drought. Households varied in both adaptation behavior and household resources and we found that, overall, households that adapted had better child nutrition than those that didn't adapt. When controlling for the influence of household capital, we found that more vulnerable households, those with greater dependence on natural resources and lower income, had a stronger positive relationship between adaptation and nutrition than less vulnerable households. We also found that some adaptations had stronger positive relationships with nutrition than others. In our system, the adaptation that most strongly correlated with improved nutrition, selling chickens, most likely benefits from local social networksand consistent demand, and performed better than other adaptations. Our results emphasize the need to measure adaptation outcomes and identify and support the types of adaptations are most likely to improve nutrition in the future.


Asunto(s)
Adaptación Psicológica , Agricultura/métodos , Cambio Climático , Agricultores , Esuatini/epidemiología , Humanos , Encuestas Nutricionales , Estado Nutricional , Salud Rural , Factores Socioeconómicos
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