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1.
Nat Commun ; 12(1): 676, 2021 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-33514729

RESUMO

Across the evolutionary history of insects, the shift from nitrogen-rich carnivore/omnivore diets to nitrogen-poor herbivorous diets was made possible through symbiosis with microbes. The herbivorous turtle ants Cephalotes possess a conserved gut microbiome which enriches the nutrient composition by recycling nitrogen-rich metabolic waste to increase the production of amino acids. This enrichment is assumed to benefit the host, but we do not know to what extent. To gain insights into nitrogen assimilation in the ant cuticle we use gut bacterial manipulation, 15N isotopic enrichment, isotope-ratio mass spectrometry, and 15N nuclear magnetic resonance spectroscopy to demonstrate that gut bacteria contribute to the formation of proteins, catecholamine cross-linkers, and chitin in the cuticle. This study identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution, and provides a framework for understanding the nitrogen flow from nutrients through bacteria into the insect cuticle.


Assuntos
Exoesqueleto/crescimento & desenvolvimento , Formigas/crescimento & desenvolvimento , Microbioma Gastrointestinal/fisiologia , Herbivoria/fisiologia , Simbiose/fisiologia , Aminoácidos/metabolismo , Animais , Formigas/metabolismo , Formigas/microbiologia , Quitina/biossíntese , Proteínas de Insetos/biossíntese , Nitrogênio/metabolismo
2.
Sci Rep ; 10(1): 22424, 2020 12 30.
Artigo em Inglês | MEDLINE | ID: mdl-33380734

RESUMO

Root-associated entomopathogenic fungi (R-AEF) indirectly influence herbivorous insect performance. However, host plant-R-AEF interactions and R-AEF as biological control agents have been studied independently and without much attention to the potential synergy between these functional traits. In this study, we evaluated behavioral responses of cabbage root flies [Delia radicum L. (Diptera: Anthomyiidae)] to a host plant (white cabbage cabbage Brassica oleracea var. capitata f. alba cv. Castello L.) with and without the R-AEF Metarhizium brunneum (Petch). We performed experiments on leaf reflectance, phytohormonal composition and host plant location behavior (behavioral processes that contribute to locating and selecting an adequate host plant in the environment). Compared to control host plants, R-AEF inoculation caused, on one hand, a decrease in reflectance of host plant leaves in the near-infrared portion of the radiometric spectrum and, on the other, an increase in the production of jasmonic, (+)-7-iso-jasmonoyl-L-isoleucine and salicylic acid in certain parts of the host plant. Under both greenhouse and field settings, landing and oviposition by cabbage root fly females were positively affected by R-AEF inoculation of host plants. The fungal-induced change in leaf reflectance may have altered visual cues used by the cabbage root flies in their host plant selection. This is the first study providing evidence for the hypothesis that R-AEF manipulate the suitability of their host plant to attract herbivorous insects.


Assuntos
Brassica/microbiologia , Brassica/parasitologia , Dípteros/fisiologia , Herbivoria/fisiologia , Metarhizium/patogenicidade , Animais , Brassica/metabolismo , Feminino , Interações entre Hospedeiro e Microrganismos/fisiologia , Modelos Biológicos , Oviposição , Controle Biológico de Vetores , Folhas de Planta/metabolismo , Raízes de Plantas/microbiologia , Simbiose
3.
Anim Sci J ; 91(1): e13481, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33161615

RESUMO

This study investigated the effect of adaptation to grazing in early spring on herbage intake, ruminal fermentation parameters, blood metabolite concentrations, and body weight change in dairy cows. The experiment was conducted on eight rumen-cannulated non-lactating cows in the early spring period. Four cows were adapted to grazing by stocking for 4 hr for 1 week (ADP group). The other cows were kept in a barn during the period (CON group). Then, both groups of cows were stocked together throughout a day on a 1 ha pasture for 3 weeks (experimental period). In the first week of the experimental period, compared to the CON group, the ADP group had a higher herbage intake, ruminal NH3 -N and total VFA concentration, and blood urea concentration, but the NEFA concentration was lower in the ADP group (p < .01). During the subsequent weeks, there were little differences in ruminal fermentation parameters and blood metabolites. Cows in the ADP group maintained their body weight, but cows in the CON group lost 60 kg of body weight in the first week of the experimental period.


Assuntos
Adaptação Fisiológica/fisiologia , Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Peso Corporal , Bovinos/metabolismo , Bovinos/fisiologia , Ingestão de Alimentos/fisiologia , Fermentação , Herbivoria/fisiologia , Rúmen/metabolismo , Estações do Ano , Amônia/metabolismo , Animais , Nitrogênio da Ureia Sanguínea , Feminino , Nitrogênio/metabolismo , Fatores de Tempo
4.
PLoS One ; 15(10): e0239755, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33052951

RESUMO

Knowledge of the recruitment of dominant forest species is a key aspect for forest conservation and the ecosystem services they provide. In this paper, we address how the simultaneous action of climate change and the intensity of land use in the past influence the recruitment of a forest species that depends on the provision of nurse plants to recruit. We compared the number of saplings (up to 15 years old) and juveniles (16 to 50 years old) of Quercus ilex in 17, 5.3 ha plots in the Iberian System (eastern Spain). We used a gradient of past deforestation intensity crossed with two levels of average annual precipitation, one of them at the lower limit of the species' precipitation niche (semi-arid) and the other at the optimum (sub-humid). We also examined the association between recruits and nurse plants and the effect on this association of plot-scale factors, such as seed abundance (reproductive Q. ilex), microsites (nurse species and soil availability), and large herbivores. The increase in aridity in the last decades has drastically reduced the recruitment of new individuals in the forests of Q. ilex located in the lower limit of their precipitation niche, regardless of the intensity of past deforestation that they suffered. Recruitment in these climatic conditions depends almost exclusively on large trees and shrubs whose abundance may also be limited by aridity. The lack of regeneration questions the future of these populations, as the number of individuals will decrease over time despite the strong resistance of adult trees to disturbance and drought.


Assuntos
Secas , Ecossistema , Quercus/fisiologia , Regeneração/fisiologia , Mudança Climática , Conservação dos Recursos Naturais/métodos , Florestas , Herbivoria/fisiologia , Estações do Ano , Solo , Espanha , Árvores/fisiologia , Água
5.
Nat Commun ; 11(1): 4904, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32994391

RESUMO

Mammalian frugivores are critical seed dispersers, but many are under threat of extinction. Futhermore, the impact of past and future defaunation on plant assemblages has yet to be quantified at the global scale. Here, we integrate palm and mammalian frugivore trait and occurrence data and reveal a global positive relationship between fruit size and frugivore body size. Global variation in fruit size is better explained by present-day frugivore assemblages than by Late Pleistocene assemblages, suggesting ecological and evolutionary reorganization after end-Pleistocene extinctions, except in the Neotropics, where some large-fruited palm species may have outlived their main seed dispersers by thousands of years. Our simulations of frugivore extinction over the next 100 years suggest that the impact of defaunation will be highest in the Old World tropics, and an up to 4% assemblage-level decrease in fruit size would be required to maintain the global body size-fruit size relationship. Overall, our results suggest that while some palm species may be able to keep pace with future defaunation through evolutionary changes in fruit size, large-fruited species may be especially vulnerable to continued defaunation.


Assuntos
Arecaceae/fisiologia , Coevolução Biológica , Conservação dos Recursos Naturais , Frutas/anatomia & histologia , Mamíferos/fisiologia , Animais , Arecaceae/anatomia & histologia , Tamanho Corporal/genética , Conjuntos de Dados como Assunto , Extinção Biológica , Frutas/genética , Herbivoria/fisiologia , Mamíferos/anatomia & histologia , Tamanho do Órgão/genética , Locos de Características Quantitativas , Dispersão de Sementes/fisiologia
6.
Proc Natl Acad Sci U S A ; 117(41): 25580-25589, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32989156

RESUMO

Anthropogenic environmental change is altering the behavior of animals in ecosystems around the world. Although behavior typically occurs on much faster timescales than demography, it can nevertheless influence demographic processes. Here, we use detailed data on behavior and empirical estimates of demography from a coral reef ecosystem to develop a coupled behavioral-demographic ecosystem model. Analysis of the model reveals that behavior and demography feed back on one another to determine how the ecosystem responds to anthropogenic forcing. In particular, an empirically observed feedback between the density and foraging behavior of herbivorous fish leads to alternative stable ecosystem states of coral population persistence or collapse (and complete algal dominance). This feedback makes the ecosystem more prone to coral collapse under fishing pressure but also more prone to recovery as fishing is reduced. Moreover, because of the behavioral feedback, the response of the ecosystem to changes in fishing pressure depends not only on the magnitude of changes in fishing but also on the pace at which changes are imposed. For example, quickly increasing fishing to a given level can collapse an ecosystem that would persist under more gradual change. Our results reveal conditions under which the pace and not just the magnitude of external forcing can dictate the response of ecosystems to environmental change. More generally, our multiscale behavioral-demographic framework demonstrates how high-resolution behavioral data can be incorporated into ecological models to better understand how ecosystems will respond to perturbations.


Assuntos
Mudança Climática , Ecossistema , Retroalimentação Fisiológica/fisiologia , Modelos Biológicos , Animais , Antozoários/fisiologia , Recifes de Corais , Peixes/fisiologia , Herbivoria/fisiologia , Atividades Humanas , Humanos
7.
Anim Sci J ; 91(1): e13454, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32959464

RESUMO

This study investigated the effects of substituting ear corn silage (ECS) for commercial formula feed on milk production and milk fatty acid profiles in grazing dairy farms during the summer season. A field survey was conducted on five grazing dairy farms in every summer month of 2017, 2018, and 2019. Three of the five farms substituted fresh ECS for the commercial formula feed at a ratio of 2:1 from July of each year (ECS farms). Other farms maintained the same feeding management as before (non-ECS farms). An interview survey was conducted on each farm to calculate feed intake and milk yield per cow. Feed and milk samples were collected in each survey. Milk compositions and milk fatty acid profiles were determined. The substitution of ECS for the commercial formula feed did not affect milk yield or milk composition, but ECS farms maintained low levels of milk urea compared with non-ECS farms (p < .01). The ECS substitution also influenced some of the milk fatty acid proportions; C16:0 and C16:1 increased, and trans-11 C18:1, cis-9,trans-11 C18:2, and the sum of polyunsaturated fatty acids decreased, while these fatty acid proportions were maintained in non-ECS farms throughout the summer season (p < .05).


Assuntos
Ração Animal , Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Bovinos/metabolismo , Bovinos/fisiologia , Indústria de Laticínios , Dieta/veterinária , Suplementos Nutricionais , Ácidos Graxos/análise , Herbivoria/fisiologia , Lactação/fisiologia , Leite/metabolismo , Silagem , Zea mays , Animais , Feminino
8.
PLoS One ; 15(7): e0236895, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735578

RESUMO

Many studies on the coexistence of wildlife with livestock have focused primarily on similar-sized species. Furthermore, many of these studies have used dietary overlap as a measure of potential competition between interacting species and thus lack the important link between dietary overlap and any negative effects on a particular species-a prerequisite for competition. Consequently, the mechanisms that drive interspecific interactions between wildlife and cattle are frequently overlooked. To address this, we used an experimental setup where we leveraged different cattle stocking rates across two seasons to identify the drivers of interspecific interactions (i.e. competition and facilitation) between smaller-bodied oribi antelope and cattle. Using direct foraging observations, we assessed dietary overlap and grass regrowth, and also calculated oribi nutritional intake rates. Ultimately, we found that cattle compete with, and facilitate, smaller-bodied oribi antelope through bottom-up control. Specifically, cattle facilitated oribi during the wet season, irrespective of cattle stocking density, because cattle foraging produced high-quality grass regrowth. In contrast, during the dry season, cattle and oribi did not co-exist in the same areas (i.e. no direct dietary overlap). Despite this, we found that cattle foraging at high densities during the previous wet season reduced the dry season availability of oribi's preferred grass species. To compensate, oribi expanded their dry season diet breadth and included less palatable grass species, ultimately reducing their nutritional intake rates. Thus, cattle competed with oribi through a delayed, across-season habitat modification. We show that differences in body size alone may not be able to offset competitive interactions between cattle and wildlife. Finally, understanding the mechanisms that drive facilitation and competition are key to promoting co-existence between cattle and wildlife.


Assuntos
Antílopes/fisiologia , Comportamento Alimentar , Gado/fisiologia , Animais , Animais Selvagens/fisiologia , Tamanho Corporal , Bovinos , Conservação dos Recursos Naturais , Dieta/veterinária , Ecologia , Ecossistema , Herbivoria/fisiologia , Poaceae , Estações do Ano , África do Sul
9.
PLoS Biol ; 18(8): e3000830, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810128

RESUMO

Plants are attacked by herbivores, which often specialize on different tissues, and in response, have evolved sophisticated resistance strategies that involve different types of chemical defenses frequently targeted to different tissues. Most known phytohormones have been implicated in regulating these defenses, with jasmonates (JAs) playing a pivotal role in complex regulatory networks of signaling interactions, often generically referred to as "cross talk." The newly identified class of phytohormones, strigolactones (SLs), known to regulate the shoot architecture, remain unstudied with regard to plant-herbivore interactions. We explored the role of SL signaling in resistance to a specialist weevil (Trichobaris mucorea) herbivore of the native tobacco, Nicotiana attenuata, that attacks the root-shoot junction (RSJ), the part of the plant most strongly influenced by alterations in SL signaling (increased branching). As SL signaling shares molecular components, such as the core F-box protein MORE AXILLARY GROWTH 2 (MAX2), with another new class of phytohormones, the karrikins (KARs), which promote seed germination and seedling growth, we generated transformed lines, individually silenced in the expression of NaMAX2, DWARF 14 (NaD14: the receptor for SL) and CAROTENOID CLEAVAGE DIOXYGENASE 7 (NaCCD7: a key enzyme in SL biosynthesis), and KARRIKIN INSENSITIVE 2 (NaKAI2: the KAR receptor). The mature stems of all transgenic lines impaired in the SL, but not the KAR signaling pathway, overaccumulated anthocyanins, as did the stems of plants attacked by the larvae of weevil, which burrow into the RSJs to feed on the pith of N. attenuata stems. T. mucorea larvae grew larger in the plants silenced in the SL pathway, but again, not in the KAI2-silenced plants. These phenotypes were associated with elevated JA and auxin (indole-3-acetic acid [IAA]) levels and significant changes in the accumulation of defensive compounds, including phenolamides and nicotine. The overaccumulation of phenolamides and anthocyanins in the SL pathway-silenced plants likely resulted from antagonism between the SL and JA pathway in N. attenuata. We show that the repressors of SL signaling, suppressor of max2-like (NaSMXL6/7), and JA signaling, jasmonate zim-domain (NaJAZs), physically interact, promoting NaJAZb degradation and releasing JASMONATE INSENSITIVE 1 (JIN1/MYC2) (NaMYC2), a critical transcription factor promoting JA responses. However, the increased performance of T. mucorea larvae resulted from lower pith nicotine levels, which were inhibited by increased IAA levels in SL pathway-silenced plants. This inference was confirmed by decapitation and auxin transport inhibitor treatments that decreased pith IAA and increased nicotine levels. In summary, SL signaling tunes specific sectors of specialized metabolism in stems, such as phenylpropanoid and nicotine biosynthesis, by tailoring the cross talk among phytohormones, including JA and IAA, to mediate herbivore resistance of stems. The metabolic consequences of the interplay of SL, JA, and IAA signaling revealed here could provide a mechanism for the commonly observed pattern of herbivore tolerance/resistance trade-offs.


Assuntos
Herbivoria/fisiologia , Interações Hospedeiro-Parasita , Lactonas/metabolismo , Caules de Planta/metabolismo , Caules de Planta/parasitologia , Transdução de Sinais , Tabaco/metabolismo , Tabaco/parasitologia , Animais , Antocianinas/metabolismo , Ciclopentanos/metabolismo , Ácidos Indolacéticos/metabolismo , Larva , Metabolômica , Oxilipinas/metabolismo , Proteínas de Plantas/metabolismo , Interferência de RNA , Gorgulhos/fisiologia
10.
PLoS One ; 15(8): e0237827, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813743

RESUMO

It is vast significance to explore the spatial and temporal evolution characteristics and influencing factors of herbivorous animal husbandry industry based on the context of China's agriculture pursuing high-quality development. In this paper, we analyze the spatial and temporal evolution of the layout of China's herbivorous animal husbandry industry and its influencing factors based on the spatial autocorrelation analysis, standard deviation ellipse, and spatial Durbin model with data from 1980 to 2017. The results show that there are significant positive autocorrelation characteristics of "high-high" aggregation and "low-low" aggregation in the Chinese herbivorous animal husbandry industry. To be specific, in the past four decades, the spatial distribution center of China's herbivorous animal husbandry industry has moved towards the northeast, crossing the boundary between agriculture and animal husbandry in China, presenting a clear trend of moving from pastoral area to agricultural area; the gradual narrowing of the spatial distribution range indicates the gradually increased degree of aggregation within the industry; the east-west stretch of spatial distribution has been strengthened, and the azimuth angle shows clockwise change, suggesting that the industrial expansion in the northeast-southwest direction is prominent; the influencing factors of changes in the spatial distribution of the industry reveal that the quantity and production capacity of productive land, people's income and living standards, and the level of mechanization will promote the development of China's herbivorous animal husbandry industry, and are essential factors influencing industrial distribution and transfer, while policy factor has small or even not significant impact on industrial aggregation, reflecting that the policy has not played the expected role, and policy support needs to be further intensified.


Assuntos
Criação de Animais Domésticos , Herbivoria/fisiologia , Indústrias , Análise Espaço-Temporal , Agricultura , Animais , China , Análise Fatorial , Geografia , Modelos Econométricos , Políticas , Análise de Regressão , Análise Espacial , Fatores de Tempo
11.
Proc Natl Acad Sci U S A ; 117(36): 21921-21927, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839326

RESUMO

Diet provides critical information about the ecology and environment of herbivores. Hence, understanding the dietary strategies of fossil herbivores and the associated temporal changes is one aspect of inferring paleoenvironmental conditions. Here, we present carbon isotope data from more than 1,050 fossil teeth that record the dietary patterns of nine herbivore families in the late Pliocene and early Pleistocene (3.6 to 1.05 Ma) from the Shungura Formation, a hominin-bearing site in southwestern Ethiopia. An increasing trend toward C4 herbivory has been observed with attendant reductions in the proportions of browsers and mixed feeders through time. A high proportion of mixed feeders has been observed prior to 2.9 Ma followed by a decrease in the proportion of mixed feeders and an increase in grazers between 2.7 and 1.9 Ma, and a further increase in the proportion of grazers after 1.9 Ma. The collective herbivore fauna shows two major change points in carbon isotope values at ∼2.7 and ∼2.0 Ma. While hominin fossils from the sequence older than 2.7 Ma are attributed to Australopithecus, the shift at ∼2.7 Ma indicating the expansion of C4 grasses on the landscape was concurrent with the first appearance of Paranthropus The link between the increased C4 herbivory and more open landscapes suggests that Australopithecus lived in more wooded landscapes compared to later hominins such as Paranthropus and Homo, and has implications for key morphological and behavioral adaptations in our lineage.


Assuntos
Dieta/história , Herbivoria/fisiologia , Hominidae/fisiologia , Poaceae/crescimento & desenvolvimento , Adaptação Fisiológica , Animais , Ecossistema , Etiópia , Comportamento Alimentar , Fósseis/história , História Antiga , Paleontologia
12.
PLoS One ; 15(6): e0235506, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32603337

RESUMO

The brown planthopper (Nilapavata lugens: BPH) and whitebacked planthopper (Sogatella furcifera: WBPH) co-occur as the principal pests of rice in Asia. A review of previous studies suggests that the two species have similar temperature tolerances and similar temperature thresholds for development. However, the distribution and seasonality of WBPH suggest that its temperature optima for performance (survival, oviposition and growth) may be lower than for BPH. We compared adult longevity, oviposition, nymph survival and development success, as well as nymph biomass in both species across a gradient of constant temperatures from 15°C-40°C, at 5°C intervals. The most suitable temperatures for oviposition, nymph biomass and development success were 5-10°C lower for WBPH than for BPH. Furthermore, compared to BPH, WBPH demonstrated clear differences in oviposition on different rice subspecies and on rice at different growth stages at 25°C and 30°C, but not at other temperatures. The results suggest that aspects of herbivore performance within tolerable temperature ranges, which are not often included in temperature models, may be more useful than thermal tolerances or development thresholds in predicting the effects of global warming on pest damage to crops.


Assuntos
Hemípteros/fisiologia , Oviposição/fisiologia , Especificidade da Espécie , Temperatura , Animais , Ásia , Produtos Agrícolas , Ecossistema , Aquecimento Global , Herbivoria/fisiologia , Modelos Teóricos , Ninfa/crescimento & desenvolvimento , Oryza , Controle de Pragas
13.
Emerg Top Life Sci ; 4(1): 33-43, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32537636

RESUMO

Plant induced responses to herbivory have long been found to function as plant direct and indirect defenses and to be major drivers of herbivore community and population dynamics. While induced defenses are generally understood as cost-saving strategies that allow plants to allocate valuable resources into defense expression, it recently became clear that, in particular, induced metabolic changes can come with significant ecological costs. In particular, interactions with mutualist pollinators can be significantly compromised by herbivore-induced changes in floral morphology and metabolism. We review recent findings on the evidence for ecological conflict between defending against herbivores and attracting pollinators while using similar modes of information transfer (e.g. visual, olfactory, tactile). Specifically, we discuss plant traits and mechanisms through which plants mediate interactions between antagonists and mutualist and present functional hypotheses for how plants can overcome the resulting conflicts.


Assuntos
Flores/metabolismo , Herbivoria/fisiologia , Plantas/metabolismo , Polinização/fisiologia , Ecologia , Interações Hospedeiro-Parasita , Fenótipo , Fenômenos Fisiológicos Vegetais , Metabolismo Secundário , Simbiose
14.
PLoS One ; 15(6): e0234515, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32525918

RESUMO

Environmentally available sodium tends to decrease with increasing elevation, and sodium resources in these sodium-poor environments are critical for the survival of herbivores. Eucalypt leaves in the subalpine Monaro region of NSW, Australia contain much less sodium than eucalypt leaves at lower elevations, and subalpine koalas obtain this much needed resource by eating the bark from some Eucalyptus mannifera trees. To better understand the availability of salty-barked trees, we searched for evidence of koala bark chewing at 100 randomly generated locations in the region. We found 318 E. mannifera trees with koala chew marks. We also analysed sodium concentrations in the bark of three unchewed E. mannifera trees from each site to determine whether there were trees with high bark sodium content that had not yet been utilized by koalas. Although 90% of unchewed trees had sodium concentrations less than 225.4 mg.kg-1 DM, some unchewed trees contained high sodium concentrations (up to 1213.1 mg.kg-1 DM). From the random survey, we can extrapolate that 11% of trees in this area have bark sodium above 300 mg.kg-1 DM, which is based on the concentration of bark sodium observed in at least moderately chewed trees. We would expect to find 0.24 of these trees per 200 m2, or 720,000 salty-barked trees in the 30 km by 20 km study area. Bark chewing by koalas is widespread in the area, and trees with salty bark are more common than initially thought. We discuss correlations with the occurrence of salty-barked trees and other landscape attributes; however, questions remain about why some E. mannifera trees have much more bark sodium than others. Studies such as this one should be expanded to identify sodium resources and their availability for other herbivorous species, since many are predicted to move to higher elevations in response to climate change.


Assuntos
Eucalyptus/química , Herbivoria/fisiologia , Micronutrientes/análise , Phascolarctidae/fisiologia , Sódio/análise , Altitude , Animais , Austrália , Mudança Climática , Casca de Planta/química , Folhas de Planta/química , Densidade Demográfica
15.
Nat Commun ; 11(1): 2529, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32439857

RESUMO

Climate warming is anticipated to make high latitude ecosystems stronger C sinks through increasing plant production. This effect might, however, be dampened by insect herbivores whose damage to plants at their background, non-outbreak densities may more than double under climate warming. Here, using an open-air warming experiment among Subarctic birch forest field layer vegetation, supplemented with birch plantlets, we show that a 2.3 °C air and 1.2 °C soil temperature increase can advance the growing season by 1-4 days, enhance soil N availability, leaf chlorophyll concentrations and plant growth up to 400%, 160% and 50% respectively, and lead up to 122% greater ecosystem CO2 uptake potential. However, comparable positive effects are also found when insect herbivory is reduced, and the effect of warming on C sink potential is intensified under reduced herbivory. Our results confirm the expected warming-induced increase in high latitude plant growth and CO2 uptake, but also reveal that herbivorous insects may significantly dampen the strengthening of the CO2 sink under climate warming.


Assuntos
Betula/metabolismo , Sequestro de Carbono , Florestas , Aquecimento Global , Herbivoria/fisiologia , Insetos/fisiologia , Animais , Betula/crescimento & desenvolvimento , Dióxido de Carbono/metabolismo , Clima Frio , Ecossistema , Nitrogênio/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Solo/química , Tempo (Meteorologia)
16.
Nat Commun ; 11(1): 2000, 2020 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332721

RESUMO

Coral reef ecosystems are among the first to fundamentally change in structure due to climate change, which leads to questioning of whether decades of knowledge regarding reef management is still applicable. Here we assess ecological responses to no-take marine reserves over two decades, spanning a major climate-driven coral bleaching event. Pre-bleaching reserve responses were consistent with a large literature, with higher coral cover, more species of fish, and greater fish biomass, particularly of upper trophic levels. However, in the 16 years following coral mortality, reserve effects were absent for the reef benthos, and greatly diminished for fish species richness. Positive fish biomass effects persisted, but the groups of fish benefiting from marine reserves profoundly changed, with low trophic level herbivores dominating the responses. These findings highlight that while marine reserves still have important roles on coral reefs in the face of climate change, the species and functional groups they benefit will be substantially altered.


Assuntos
Antozoários/fisiologia , Mudança Climática , Conservação dos Recursos Naturais , Recifes de Corais , Peixes/fisiologia , Animais , Monitorização de Parâmetros Ecológicos/estatística & dados numéricos , Herbivoria/fisiologia , Dinâmica Populacional/tendências , Seicheles
17.
PLoS One ; 15(3): e0212530, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32155150

RESUMO

The Ngorongoro Crater is an intact caldera with an area of approximately 310 km2 located within the Ngorongoro Conservation Area (NCA) in northern Tanzania. It is known for the abundance and diversity of its wildlife and is a UNESCO World Heritage Site and an International Biosphere Reserve. Long term records (1963-2012) on herbivore populations, vegetation and rainfall made it possible to analyze historic and project future herbivore population dynamics. NCA was established as a multiple use area in 1959. In 1974 there was a perturbation in that resident Maasai and their livestock were removed from the Ngorongoro Crater. Thus, their pasture management that was a combination of livestock grazing and fire was also removed and 'burning' stopped being a regular occurrence until it was resumed in 2001 by NCA management. The Maasai pasture management would have selected for shorter grasses and more palatable species. Vegetation mapping in 1966-1967 recorded predominately short grasslands. Subsequent vegetation mapping in the crater in 1995 determined that the grassland structure had changed such that mid and tall grasses were dominant. After removal of the Maasai pastoralists from the Ngorongoro Crater in 1974, there were significant changes in population trends for some herbivore species. Buffalo, elephant and ostrich numbers increased significantly during 1974-2012. The zebra population was stable from 1963 to 2012 whereas population numbers of five species declined substantially between 1974 and 2012 relative to their peak numbers during 1974-1976. Grant's and Thomson's gazelles, eland, kongoni, and waterbuck (wet season only) declined significantly in the Crater in both seasons after 1974. In addition, some herbivore species were consistently more abundant inside the Crater during the wet than the dry season. This pattern was most evident for the large herbivore species requiring bulk forage, i.e., buffalo, eland, and elephant. Even with a change in grassland structure, total herbivore biomass remained relatively stable from 1963 to 2012, implying that the crater has a stable carrying capacity. Analyses of rainfall indicated that there was a persistent cycle of 4.83 years for the annual component. Herbivore population size was correlated with rainfall in both the wet and dry seasons. The relationships established between the time series of historic animal counts in the wet and dry seasons and lagged wet and dry season rainfall series were used to forecast the likely future trajectories of the wet and dry season population size for each species under three alternative climate change scenarios.


Assuntos
Animais Selvagens/crescimento & desenvolvimento , Herbivoria/fisiologia , Animais , Biomassa , Geografia , Densidade Demográfica , Dinâmica Populacional , Chuva , Análise de Regressão , Estações do Ano , Tanzânia , Temperatura , Fatores de Tempo
18.
Proc Natl Acad Sci U S A ; 117(14): 7871-7878, 2020 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32205427

RESUMO

Large-bodied mammalian herbivores dominated Earth's terrestrial ecosystems for several million years before undergoing substantial extinctions and declines during the Late Pleistocene (LP) due to prehistoric human impacts. The decline of large herbivores led to widespread ecological changes due to the loss of their ecological functions, as driven by their unique combinations of traits. However, recently, humans have significantly increased herbivore species richness through introductions in many parts of the world, potentially counteracting LP losses. Here, we assessed the extent to which introduced herbivore species restore lost-or contribute novel-functions relative to preextinction LP assemblages. We constructed multidimensional trait spaces using a trait database for all extant and extinct mammalian herbivores ≥10 kg known from the earliest LP (∼130,000 ybp) to the present day. Extinction-driven contractions of LP trait space have been offset through introductions by ∼39% globally. Analysis of trait space overlap reveals that assemblages with introduced species are overall more similar to those of the LP than native-only assemblages. This is because 64% of introduced species are more similar to extinct rather than extant species within their respective continents. Many introduced herbivores restore trait combinations that have the capacity to influence ecosystem processes, such as wildfire and shrub expansion in drylands. Although introduced species have long been a source of contention, our findings indicate that they may, in part, restore ecological functions reflective of the past several million years before widespread human-driven extinctions.


Assuntos
Evolução Biológica , Herbivoria/genética , Espécies Introduzidas , Mamíferos/genética , Animais , Biodiversidade , Ecossistema , Extinção Biológica , Herbivoria/fisiologia , Humanos
19.
PLoS One ; 15(3): e0230509, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32218604

RESUMO

Vegetative parts of bilberry (Vaccinium myrtillus) are important forage for many boreal forest mammal, bird and insect species. Plant palatability to insects is affected by concentration of nutrients and defense compounds in plants. We expected that palatability of bilberry leaves to insect herbivores is influenced by light availability and soil productivity (both affecting nitrogen concentration and constitutive carbon-based defense compound concentration) and herbivory by mammals (affecting nitrogen concentration and induced carbon-based defense compound concentration). We studied bilberry leaf herbivory under different light availability, soil productivity and mammalian herbivory pressure in small sampling units (1m x 1m) in boreal forest in Norway. We used generalized linear mixed models and generalized additive mixed models to model insect herbivory on bilberry leaves as a function of shade, soil productivity and mammalian herbivory. Observed insect herbivory on bilberry leaves increased with increasing shade levels. Predicted insect herbivory increased with increasing previous mammalian herbivory at high shade levels and this response was magnified at higher soil productivity levels. At low to intermediate shade levels, this response was only present under high soil productivity levels. Our results indicate that light availability is more important for variation in bilberry leaf palatability than soil nutrient conditions.


Assuntos
Herbivoria/fisiologia , Insetos/fisiologia , Mamíferos/fisiologia , Modelos Biológicos , Folhas de Planta/crescimento & desenvolvimento , Solo , Luz Solar , Vaccinium myrtillus/crescimento & desenvolvimento , Animais
20.
Sci Rep ; 10(1): 5103, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198395

RESUMO

Despite the wide knowledge about prevalent effects of ocean acidification on single species, the consequences on species interactions that may promote or prevent habitat shifts are still poorly understood. Using natural CO2 vents, we investigated changes in a key tri-trophic chain embedded within all its natural complexity in seagrass systems. We found that seagrass habitats remain stable at vents despite the changes in their tri-trophic components. Under high pCO2, the feeding of a key herbivore (sea urchin) on a less palatable seagrass and its associated epiphytes decreased, whereas the feeding on higher-palatable green algae increased. We also observed a doubled density of a predatory wrasse under acidified conditions. Bottom-up CO2 effects interact with top-down control by predators to maintain the abundance of sea urchin populations under ambient and acidified conditions. The weakened urchin herbivory on a seagrass that was subjected to an intense fish herbivory at vents compensates the overall herbivory pressure on the habitat-forming seagrass. Overall plasticity of the studied system components may contribute to prevent habitat loss and to stabilize the system under acidified conditions. Thus, preserving the network of species interactions in seagrass ecosystems may help to minimize the impacts of ocean acidification in near-future oceans.


Assuntos
Alismatales/crescimento & desenvolvimento , Peixes/fisiologia , Herbivoria/fisiologia , Ouriços-do-Mar/fisiologia , Água do Mar/química , Animais , Ecossistema , Concentração de Íons de Hidrogênio , Fontes Hidrotermais , Oceanos e Mares
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