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1.
Trends Microbiol ; 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39358066

RESUMO

Decomposer microbial communities are gatekeepers in the redistribution of carbon and nutrients from dead animals (carrion) to terrestrial ecosystems. The flush of decomposition products from a carcass creates a hot spot of microbial activity in the soil below, and the animal's microbiome is released into the environment, mixing with soil communities. Changes in soil physicochemistry, especially reduced oxygen, temporarily constrain microbial nutrient cycling, and influence the timing of these processes and the fate of carrion resources. Carcass-related factors, such as mass, tissue composition, or even microbiome composition may also influence the functional assembly and succession of decomposer communities. Understanding these local scale microbially mediated processes is important for predicting consequences of carrion decomposition beyond the hot spot and hot moment.

2.
Sci Rep ; 14(1): 24135, 2024 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-39406878

RESUMO

The increasing abundance of animal species thriving in urban environments is a source of conflicts with managers and users of public spaces. Although opportunistic urban species often use resources originating from human food leftovers, the potential impact of a reduction in these resources on their demography is hard to quantify. The COVID-19 epidemic, which led many countries to set up lockdowns, gave us the opportunity to estimate the impact of a drastic reduction in such food resources and human activities on the demography of an urban bird population. Based on 7 years (2015-2021) of capture-mark-recapture of carrion crows (Corvus corone) in the city of Paris, France, we used multi-state models to examine the intra-annual (3-month time steps) apparent survival and movement patterns of crows during and outside COVID-19 lockdowns. We showed that the apparent survival of juvenile carrion crows decreased down during lockdown, while adult movements increased during this period, with more adult crows moving out of the urban district. Lockdown modified the demography of this urban crow population, suggesting that the reduction in food resources was sufficient to affect fitness and reduce carrying capacity.


Assuntos
COVID-19 , Corvos , Corvos/fisiologia , Animais , COVID-19/epidemiologia , COVID-19/mortalidade , COVID-19/prevenção & controle , Humanos , SARS-CoV-2/isolamento & purificação , Quarentena , Paris/epidemiologia , População Urbana , Dinâmica Populacional , Cidades/epidemiologia
3.
Ecol Evol ; 14(9): e70203, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39224157

RESUMO

Silphinae (Staphylinidae; carrion beetles) are important contributors to the efficient decomposition and recycling of carrion necromass. Their community composition is important for the provision of this ecosystem function and can be affected by abiotic and biotic factors. However, investigations are lacking on the effects of carrion characteristics on Silphinae diversity. Carrion body mass may affect Silphinae diversity following the more individuals hypothesis (MIH). The MIH predicts a higher number of species at larger carrion because higher numbers of individuals can be supported on the resource patch. Additionally, biotic factors like carrion species identity or decomposition stage, and the abiotic factors elevation, season and temperature could affect Silphinae diversity. To test the hypotheses, we collected Silphinae throughout the decomposition of 100 carcasses representing 10 mammal species ranging from 0.04 to 124 kg. Experimental carcasses were exposed in a mountain forest landscape in Germany during spring and summer of 2021. We analysed Silphinae diversity using recently developed transformation models that considered the difficult data distribution we obtained. We found no consistent effect of carrion body mass on Silphinae species richness and, therefore, rejected the MIH. Carrion decomposition stage, in contrast, strongly influenced Silphinae diversity. Abundance and species richness increased with the decomposition process. Silphinae abundance increased with temperature and decreased with elevation. Furthermore, Silphinae abundance was lower in summer compared to spring, likely due to increased co-occurrence and competition with dipteran larvae in summer. Neither carrion species identity nor any abiotic factor affected Silphinae species richness following a pattern consistent throughout the seasons. Our approach combining a broad study design with an improved method for data analysis, transformation models, revealed new insights into mechanisms driving carrion beetle diversity during carrion decomposition. Overall, our study illustrates the complexity and multifactorial nature of biotic and abiotic factors affecting diversity.

4.
Emerg Infect Dis ; 30(10): 2099-2107, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39320166

RESUMO

Bartonella spp. are opportunistic, vectorborne bacteria that can cause disease in both animals and humans. We investigated the molecular occurrence of Bartonella spp. in 634 phlebotomine sand fly specimens, belonging to 44 different sand fly species, sampled during 2017-2021 in north and northeastern Brazil. We detected Bartonella sp. DNA in 8.7% (55/634) of the specimens by using a quantitative real-time PCR targeting the 16S-23S internal transcribed spacer intergenic region. Phylogenetic analysis positioned the Lutzomyia longipalpis sand fly-associated Bartonella gltA gene sequence in the same subclade as Bartonella ancashensis sequences and revealed a Bartonella sp. sequence in a Dampfomyia beltrani sand fly from Mexico. We amplified a bat-associated Bartonella nuoG sequence from a specimen of Nyssomyia antunesi sand fly. Our findings document the presence of Bartonella DNA in sand flies from Brazil, suggesting possible involvement of these insects in the epidemiologic cycle of Bartonella species.


Assuntos
Infecções por Bartonella , Bartonella , Insetos Vetores , Filogenia , Psychodidae , Animais , Bartonella/genética , Bartonella/isolamento & purificação , Bartonella/classificação , Brasil/epidemiologia , Psychodidae/microbiologia , Insetos Vetores/microbiologia , Infecções por Bartonella/microbiologia , Infecções por Bartonella/epidemiologia , Infecções por Bartonella/transmissão , DNA Bacteriano/genética
5.
Oecologia ; 206(1-2): 115-126, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39251421

RESUMO

Resource availability and habitat heterogeneity are essential drivers of biodiversity, but their individual roles often remain unclear since both factors are often correlated. Here, we tested the more-individuals hypothesis (MIH) and the habitat-heterogeneity hypothesis (HHH) for bacteria, fungi, dipterans, coleopterans, birds, and mammals on 100 experimentally exposed carcasses ranging by three orders of magnitude in body mass. At the level of each carcass we found marginal or significant support for the MIH for bacteria, fungi, and beetles in spring and significant support for fungi, dipterans, and mammals in summer. The HHH was supported only for bacteria in spring, while it was supported for all groups except mammals in summer. Overall multidiversity always increased with body mass, with a steeper increase in summer. Abundance based rarefaction-extrapolation curves for three classes of body mass showed the highest species richness for medium-sized carcasses, particular for dipterans and microbes, supporting the HHH also among carcasses. These findings complement existing necromass studies of deadwood, showing there are more niches associated with larger resource amounts and an increasing habitat heterogeneity between carcasses most pronounced for medium-sized species. Higher resource amount led to increased diversity of carrion-consuming organisms in summer, particularly due to the increasing number of niches with increasing size. Our findings underline the importance of distributed large carrion as well as medium-sized carrion in ecosystems supporting overall biodiversity of carrion-consumers. Furthermore, the different responses in spring and summer may inform strategies of carrion enrichment management schemes throughout the year.


Assuntos
Biodiversidade , Ecossistema , Animais , Besouros , Mamíferos , Aves , Bactérias/classificação , Fungos
6.
Ecol Evol ; 14(8): e70211, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39206457

RESUMO

Scavenging on carrion is critical and often fiercely competitive for a range of vertebrate species, from native apex predators to invasive species and even reptiles. Within Australia, a notable reptilian scavenger is the lace monitor (Varanus varius). In this study, we quantified lace monitor activity at carcasses and compared their use of the resource to common co-occurring predators that also scavenge; the invasive red fox (Vulpes vulpes) and a native apex predator, the dingo (Canis dingo). To do so, we deployed 80 macropod carcasses equally across seasons (summer and winter) and habitats (open and closed canopy) in a temperate bioregion and monitored vertebrate scavenging with camera traps. Lace monitor activity (visitation at carcass sites inclusive of both non-scavenging and scavenging events) was 1.67 times higher in summer than in winter, but it did not differ across closed and open habitats. Monitor activity occurred earlier after carcass deployment at sites deployed in summer than winter (1.47-fold earlier), and at carcasses in open than closed habitats (0.22-fold earlier). Lace monitors initially discovered carcass sites faster in summer than winter and before both red foxes and dingoes in summer. The species was active diurnally in both summer and winter, differing from the red fox, which was strictly a nocturnal scavenger and the dingo, which was significantly more active at night across both seasons. Finally, we found that lace monitor activity at carcass sites decreased slightly with higher rates of activity for dingoes (0.04-fold decrease as dingo activity increased), but not with red fox activity. Our results have implications for understanding lace monitor foraging and scavenging and highlight the value of monitoring carcasses to provide important insights into the behaviour of varanid lizards that scavenge.

7.
R Soc Open Sci ; 11(7): 240409, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39086817

RESUMO

Vultures provide the key ecosystem service of quickly removing carrion, so they have recently been assumed to be top scavengers. To challenge the concept of top scavenger (i.e. the most influential in the scavenging community and process), between 2012 and 2019, we recorded the consumption of 45 equine carcasses available for two different avian scavenger guilds in the Tropical Andes; each guild included the Andean Condor, the alleged top scavenger. The carcasses eaten by Andean Condors were consumed, on average, 1.75 times faster than those they did not eat. Furthermore, the greater abundance of feeding condors shortened carcass consumption time more than a greater abundance of any other species by 1.65 to 5.96 times, on average. These findings support the hypothesis that the Andean Condor significantly drives scavenging dynamics and is, therefore, an unrestricted top scavenger. Additionally, we established a gradient of tolerance of avian scavengers to domestic dog disturbance at carcasses, from highest to lowest: vultures > caracaras > condors. Our study framework holds great potential for advancing in food webs' comprehension through quantifying the relative functional role of scavenging communities' members and for guiding efforts to weigh up the ecological contributions of top scavengers and foster their conservation.

8.
Oecologia ; 206(1-2): 21-35, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39153020

RESUMO

The decomposition of carcasses by scavengers and microbial decomposers is an important component of the biochemical cycle that can strongly alter the chemical composition of soils locally. Different scavenger guilds are assumed to have a different influence on the chemical elements that leak into the soil, although this assumption has not been empirically tested. Here, we experimentally determine how different guilds of vertebrate scavengers influence local nutrient dynamics. We performed a field experiment in which we systematically excluded different subsets of vertebrate scavengers from decomposing carcasses of fallow deer (Dama dama), and compared elemental concentrations in the soil beneath and in the vegetation next to the carcasses over time throughout the decomposition process. We used four exclusion treatments: excluding (1) no scavengers, thus allowing them all; (2) wild boar (Sus scrofa); (3) all mammals; and (4) all mammals and birds. We found that fluxes of several elements into the soil showed distinct peaks when all vertebrates were excluded. Especially, trace elements (Cu and Zn) seemed to be influenced by carcass decomposition. However, we found no differences in fluxes between partial exclusion treatments. Thus, vertebrate scavengers indeed reduce leakage of elements from carcasses into the soil, hence influencing local biochemical cycles, but did so independent of which vertebrate scavenger guild had access. Our results suggest that carcass-derived elements are dispersed over larger areas rather than locally leak into the soil when vertebrate scavengers dominate the decomposition process.


Assuntos
Solo , Animais , Solo/química , Vertebrados , Cervos , Nutrientes , Sus scrofa
9.
Insects ; 15(7)2024 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-39057282

RESUMO

A series of experiments were conducted on Phormia regina, a forensically important blow fly species, that met the requirements needed to create statistically valid development models. Experiments were conducted over 11 temperatures (7.5 to 32.5 °C, at 2.5 °C intervals) with a 16:8 L:D cycle. Experimental units contained 20 eggs, 10 g of beef liver, and 2.5 cm of sand. Each life stage (egg to adult) had five sampling times. Each sampling time was replicated four times for a total of 20 measurements per life stage. For each sampling time, the cups were pulled from the chambers, and the stage of each maggot was documented morphologically through posterior spiracular slits and cephalopharyngeal development. Data were normally distributed with the later larval (L3m) and pupation stages having the most variation within and transitioning between stages, particularly between 12.5 °C and 20.0 °C. The biological minimum was between 10.0 °C and 12.5 °C, with little egg development and no egg emergence at 7.5 °C and no maturation past L1 at 10.0 °C. Phormia regina did not display increased mortality associated with the upper temperature of 32.5 °C. The development data generated illustrate the advantages of large data sets in modeling blow fly development and the need for curvilinear models in describing development at environmental temperatures near the biological minima and maxima.

10.
PeerJ ; 12: e17636, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38993975

RESUMO

Environmental DNA (eDNA) analyses are an increasingly popular tool for assessing biodiversity. eDNA sampling that uses invertebrates, or invertebrate DNA (iDNA), has become a more common method in mammal biodiversity studies where biodiversity is assessed via diet analysis of different coprophagous or hematophagous invertebrates. The carrion feeding family of beetles (Silphidae: Coleoptera, Latreille (1807)), have not yet been established as a viable iDNA source in primary scientific literature, yet could be useful indicators for tracking biodiversity in forested ecosystems. Silphids find carcasses of varying size for both food and reproduction, with some species having host preference for small mammals; therefore, iDNA Silphid studies could potentially target small mammal communities. To establish the first valid use of iDNA methods to detect Silphid diets, we conducted a study with the objective of testing the validity of iDNA methods applied to Silphids using both Sanger sequencing and high throughput Illumina sequencing. Beetles were collected using inexpensive pitfall traps in Alberta, Michigan in 2019 and 2022. We successfully sequenced diet DNA and environmental DNA from externally swabbed Silphid samples and diet DNA from gut dissections, confirming their potential as an iDNA tool in mammalian studies. Our results demonstrate the usefulness of Silphids for iDNA research where we detected species from the genera Anaxyrus, Blarina, Procyon, Condylura, Peromyscus, Canis, and Bos. Our results highlight the potential for Silphid iDNA to be used in future wildlife surveys.


Assuntos
Besouros , Animais , Besouros/genética , Biodiversidade , DNA Ambiental/genética , DNA Ambiental/análise , Dieta/veterinária , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Estudo de Prova de Conceito , Michigan , Análise de Sequência de DNA/métodos
11.
J Environ Manage ; 365: 121554, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38905791

RESUMO

Vertebrate scavengers provide essential ecosystem services such as accelerating carrion decomposition by consuming carcasses, exposing tissues to microbial and invertebrate decomposers, and recycling nutrients back into the ecosystem. Some scavengers do not consume carcasses on site but rather scatter their remains in the surroundings, which might have important implications for nutrient transport, forensic investigations and the spread of diseases such as African Swine Fever. However, only a few studies have investigated and measured the scatter distances. Using wild boar (Sus scrofa) carcasses and limbs, we monitored scavenging behavior and measured scatter distances of mammals. We placed 20 carcasses (up to 25 kg) and 21 separate limbs equipped with very high frequency (VHF) transmitters and monitored scavenger activity using camera traps in a mountainous region in southeast Germany. Except for one carcass, all other carcasses and limbs were scattered. We measured 72 scatter distances (of 89 scattering events; mean = 232 m, maximum = 1250 m), of which 75% were dispersed up to 407 m. Scavengers moved scattered pieces into denser vegetation compared to the half-open vegetation at provisioning sites. Red foxes (Vulpes vulpes) were the most common scavenger species, contributing to 72 scattering events (58 measured scatter distances). Our results provide evidence of scatter distances farther than previously assumed and have far-reaching implications for disease management or forensic investigations, as the broader surroundings of carcasses must be included in search efforts to remove infectious material or relevant body parts for forensic analysis.


Assuntos
Sus scrofa , Animais , Suínos , Ecossistema , Febre Suína Africana , Alemanha , Raposas
12.
Mol Ecol ; 33(13): e17421, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38828760

RESUMO

For most animals, the microbiome is key for nutrition and pathogen defence, and is often shaped by diet. Corbiculate bees, including honey bees, bumble bees, and stingless bees, share a core microbiome that has been shaped, at least in part, by the challenges associated with pollen digestion. However, three species of stingless bees deviate from the general rule of bees obtaining their protein exclusively from pollen (obligate pollinivores) and instead consume carrion as their sole protein source (obligate necrophages) or consume both pollen and carrion (facultative necrophages). These three life histories can provide missing insights into microbiome evolution associated with extreme dietary transitions. Here, we investigate, via shotgun metagenomics, the functionality of the microbiome across three bee diet types: obligate pollinivory, obligate necrophagy, and facultative necrophagy. We find distinct differences in microbiome composition and gene functional profiles between the diet types. Obligate necrophages and pollinivores have more specialized microbes, whereas facultative necrophages have a diversity of environmental microbes associated with several dietary niches. Our study suggests that necrophagous bee microbiomes may have evolved to overcome cellular stress and microbial competition associated with carrion. We hypothesize that the microbiome evolved social phenotypes, such as biofilms, that protect the bees from opportunistic pathogens present on carcasses, allowing them to overcome novel nutritional challenges. Whether specific microbes enabled diet shifts or diet shifts occurred first and microbial evolution followed requires further research to disentangle. Nonetheless, we find that necrophagous microbiomes, vertebrate and invertebrate alike, have functional commonalities regardless of their taxonomy.


Assuntos
Dieta , Metagenômica , Microbiota , Pólen , Animais , Abelhas/microbiologia , Pólen/microbiologia , Microbiota/genética , Polinização
13.
Ecol Evol ; 14(6): e11444, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38895572

RESUMO

Despite global declines in the abundance and distribution of predators, conservation and reintroduction efforts are increasingly leading to predator recoveries. Unexpected species interactions and ecological consequences often arise when these predator recoveries occur. Here, we describe a novel species interaction in which coyotes (Canis latrans) kleptoparasitize North American river otters (Lontra canadensis) in a region of river otter recovery along the north-central California coast, USA. We describe eight observations of coyotes scavenging otter-killed waterbird carrion, including one observation in which river otters aggressively defended their prey from a coyote kleptoparasite. These observations highlight the importance of carrion provisioning as an overlooked pathway through which river otters facilitate nutrient subsidies to terrestrial scavengers. This behavior may have ecological implications including effects on the abundance, behavior, and health of scavengers as well as their interspecific interactions. We propose hypotheses and questions regarding these ecological consequences to guide further investigations into the cross-ecosystem impacts of recovering river otter populations.

14.
Naturwissenschaften ; 111(3): 30, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38758365

RESUMO

Succession patterns of carrion insects on large mammal's carrion has been widely studied, notably to estimate the post-mortem interval in forensic investigations as accurately as possible. However, little attention has been paid to the carrion insects living inside these bones once a carcass is skeletonized. One very recent study documented flies emerging from pig carcasses, and only scarce authors reported the presence of other carrion insects taking advantage of the bone marrow. We, thus, aimed to (1) estimate the frequency of inner-bone space colonization by carrion insects, with particular attention to bone-skipper flies; (2) identify the insects living inside the carrion bones; and (3) determine whether or not carrion insects found within the bones can successfully exit the bones and complete their development. We extensively sampled 185 large mammals' bones collected from twelve vulture feeding stations and four isolated carcasses in southwest France and northern Spain. Sampled bones were opened, and the insects found inside were identified. For two bones, foramen, i.e., the holes providing a natural entrance and exit to the bone's inner cavity, was monitored with a camera to assess the insect's putative exit. We describe the entomofauna, i.e., the set of insect species, living within the bones, and illustrate insects' ability to exit the bones for their subsequent development and maturity. These results are discussed in the framework of carrion insect conservation and forensic entomology perspectives.


Assuntos
Osso e Ossos , Entomologia Forense , Insetos , Mamíferos , Animais , Osso e Ossos/anatomia & histologia , Insetos/fisiologia , França , Espanha , Comportamento Alimentar/fisiologia , Dípteros/fisiologia , Dípteros/anatomia & histologia
15.
Behav Processes ; 219: 105055, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38777168

RESUMO

In the biological sciences, sexual behaviours in non-human animals are traditionally investigated in the context of reproduction and direct fitness benefits. While the evolutionary functions of non-conceptive sexual behaviours ('socio-sexual behaviours') remain less well explored, these interactions and displays have been suggested to be important for shaping and maintaining social relationships. Here, we report an observation of a captive female carrion crow, Corvus corone corone, mounting her co-housed male partner. We highlight the importance of more systematic research, reporting, and discussions of rarely observed behaviours in social evolution research, including considerations for behaviours that transcend binary or heteronormative frameworks, for a more comprehensive understanding of non-conceptive socio-sexual behaviours.


Assuntos
Corvos , Comportamento Sexual Animal , Animais , Corvos/fisiologia , Feminino , Masculino , Comportamento Sexual Animal/fisiologia , Comportamento Social , Copulação/fisiologia
16.
Ecol Evol ; 14(4): e10935, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38571788

RESUMO

Scavenging mammals and vultures can exploit and deplete carcasses much faster than other birds and invertebrates. Vultures are strongly influenced by habitat type, e.g. tree cover, since they rely on their eyesight to detect carcasses. It remains unclear whether and how facultative scavengers - both other birds and mammals - are influenced by tree cover and how that affect carcass decomposition time, which in turn affects biodiversity and ecological processes, including the cycle of energy and nutrients. We studied whether the carcass detection and consumption, hence carcass decomposition speed, by facultative avian and mammalian scavengers varies with tree cover in areas without vultures. Fresh mammal carcasses were placed in different landscapes across the Netherlands at locations that widely varied in tree cover. Camera traps were used to record carcass exploitation by facultative avian and mammalian scavengers and to estimate carcass decomposition time. We found that carcass detection and consumption by birds, wild boar, and other mammals varied between locations. Carcass decomposition speed indeed increased with carcass detection and exploitation by mammals, especially by wild boar. However, this variation was not related to tree cover. We conclude that tree cover is not a major determinant of carcass exploitation by facultative scavengers in areas without obligate scavengers and large carnivores.

17.
Oecologia ; 204(4): 861-874, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38589583

RESUMO

Scavenging dynamics are influenced by many abiotic and biotic factors, but there is little knowledge of how scavengers respond to extreme weather events. As carrion is a major driver of the organisation and structure of food webs within ecological communities, understanding the response of scavengers to extreme weather events is critical in a world that is increasingly subject to climate change. In this study, vertebrate scavenging and carcass persistence rates were quantified in the Simpson Desert of central Australia; a system that experiences major fluctuations and extremes in weather conditions. Specifically, a total of 80 adult red kangaroo (Osphranter rufus) carcasses were placed on the landscape and monitored using remote sensor cameras. This included 40 carcasses monitored before and then 40 carcasses monitored after a major flooding event. The carcasses were monitored equally before and after the flood across different seasons (warm and cool) and in dune and interdune habitats. Overall, a total of 8124 scavenging events for 97,976 visitation minutes were recorded for 11 vertebrate species within 30 days of carcass placement pre- and post-flood. Vertebrate scavenging increased post-flood in the warm season, especially by corvids which quadrupled their scavenging events during this time. There was little difference in carcass persistence between habitats, but carcasses persisted 5.3-fold longer post-flood in warm seasons despite increased vertebrate scavenging. The results demonstrate that a flood event can influence scavenging dynamics and suggest a need to further understand how seasons, habitats and extreme weather events can drive changes in carrion-based food webs.


Assuntos
Ecossistema , Inundações , Estações do Ano , Animais , Austrália , Vertebrados/fisiologia , Cadeia Alimentar , Mudança Climática
18.
Zool Res ; 45(3): 451-463, 2024 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-38583936

RESUMO

The gut microbiota significantly influences host physiology and provides essential ecosystem services. While diet can affect the composition of the gut microbiota, the gut microbiota can also help the host adapt to specific dietary habits. The carrion crow ( Corvus corone), an urban facultative scavenger bird, hosts an abundance of pathogens due to its scavenging behavior. Despite this, carrion crows infrequently exhibit illness, a phenomenon related to their unique physiological adaptability. At present, however, the role of the gut microbiota remains incompletely understood. In this study, we performed a comparative analysis using 16S rRNA amplicon sequencing technology to assess colonic content in carrion crows and 16 other bird species with different diets in Beijing, China. Our findings revealed that the dominant gut microbiota in carrion crows was primarily composed of Proteobacteria (75.51%) and Firmicutes (22.37%). Significant differences were observed in the relative abundance of Enterococcus faecalis among groups, highlighting its potential as a biomarker of facultative scavenging behavior in carrion crows. Subsequently, E. faecalis isolated from carrion crows was transplanted into model mice to explore the protective effects of this bacterial community against Salmonella enterica infection. Results showed that E. faecalis down-regulated the expression of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), and interleukin 6 (IL-6), prevented S. enterica colonization, and regulated the composition of gut microbiota in mice, thereby modulating the host's immune regulatory capacity. Therefore, E. faecalis exerts immunoregulatory and anti-pathogenic functions in carrion crows engaged in scavenging behavior, offering a representative case of how the gut microbiota contributes to the protection of hosts with specialized diets.


Assuntos
Corvos , Animais , Camundongos , Enterococcus faecalis , Ecossistema , RNA Ribossômico 16S , Comportamento Alimentar , Aves
19.
Insect Sci ; 2024 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-38480671

RESUMO

Aggregations of juveniles are dominant forms of social life in some insect groups. Larval societies are shaped by competitive and cooperative interactions of the larvae, in parallel with parental effects. Colonies of necrophagous larvae are excellent systems to study these relationships. Necrodes littoralis (Staphylinidae: Silphinae), a carrion beetle that colonizes cadavers of large vertebrates, forms massive juvenile aggregations. By spreading over carrion anal and oral exudates, the beetles form the feeding matrix, in which the heat is produced and by which adults presumably affect the fitness of the larvae. We predict that exploitative competition shapes the behavior of N. littoralis larvae in their aggregations. However, cooperative interactions may also operate in these systems due mainly to the benefits of collective exodigestion. Moreover, indirect parental effects (i.e., formation of the feeding matrix) probably modulate larval interactions within the aggregations. By manipulating parental effects (present/absent) and larval density (0.02-1.9 larvae/g of meat), we found a strong negative group-size effect on fitness components of N. littoralis, in colonies with parental effects over almost the entire density range, and in colonies without parental effects for densities larger than 0.5 larva/g. This was accompanied by positive group-size effects in terms of development time (it shortened with larval density) and thermogenesis (it increased with larval density). A pronounced positive group-size effect on juvenile fitness was found only in colonies without parental effects and only in the low-density range. These results support the hypothesis that larval societies of N. littoralis are shaped by exploitation competition.

20.
Int J Legal Med ; 138(4): 1669-1684, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38374286

RESUMO

The identification of unknown human remains is a significant and ongoing challenge in South Africa, worsened by the country's high murder rate. The rate of decomposition in South Africa is significantly influenced by vertebrate scavenging, which, if not considered, can impede the accurate estimation of the post-mortem interval. Scavenging patterns vary greatly depending on the environment and ecological region, and there is limited data for the Western Cape province. To address this gap, two clothed and uncaged pig carcasses weighing 60 kg each were placed in the field in July 2021 and January 2022, respectively. Motion-activated infrared-capable trail cameras were used to observe decomposition, scavenger species, and their activities. Additionally, a comparative sample of 16 unclothed carcasses deployed between 2014 and 2016 in the same habitat were analyzed to assess the impact of clothing and biomass load. The study found three main results: (1) Regardless of habitat or biomass load, it took significantly less time to reach decomposition milestones (25%, 50%, and 75%) during the summer season; (2) the presence of mongoose scavengers had a greater impact on the time required to reach milestones during winter compared to summer; and (3) single carcass deployments reached the milestones faster than multi-carcass deployments in both seasons. This research highlights the potential inaccuracy of current methods for estimating the post-mortem interval when scavenging activity is not considered or documented in the underlying experimental data, particularly for environments or ecological biomes where scavengers actively impact decomposition rates.


Assuntos
Biomassa , Vestuário , Comportamento Alimentar , Mudanças Depois da Morte , Estações do Ano , Animais , África do Sul , Suínos , Modelos Animais , Patologia Legal/métodos
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