Food Webs最新文献

Butterfly species are regarded as one of the most important members of the plant-pollinator guild. They mainly feed on nectar, and occasionally they rely on pollen. It was reported that butterfly species collect nectar from a greater array of plants. Emperical studies demonstrate that morphological variables of the butterfly species play an important role in foraging. Four morphological variables and two indices, viz., proboscis length, wing span, body length, and weight, and proboscis index and the wing load index of the butterfly species, were used to check their effect on foraging behavior on two plants, viz., Lantana camara (LCA) and Tridax procumbens (TPR), for the current study. Wing load index emerged as the most sensitive factor for foraging on these two plants. Both plants have the highest rate of visits by the butterfly species, with Lantana camara being more frequently visited than Tridax procumbens (TPR). We can conclude that the information gained from this study may help to conserve and sustain the butterfly community in the wild, and this, in turn, may also help to facilitate conservation strategies for the naturally growing nectaring plant species.

Trophic interactions can be both ephemeral and difficult to document, rendering their sampling often incomplete and context-dependent, which makes construction, analysis, and comparison of food webs challenging. Biological traits are central in determining co-occurrence of species (through dispersal, environmental, and interaction filters), as well as the potential for species interactions (through trait matching). Thereby, supplementing empirical, taxonomy-based information on trophic links with trait-based inference may help us build more realistic and adaptable food webs. Here, we go beyond taxonomy to document (i) how traits (e.g., body size, metabolic category and feeding strategy) contribute to local food web structure, and (ii) how associations of consumer-resource traits are structured. We built a trophic-link based trait-interaction network—or trait web—by combining multivariate approaches and network analysis. We found that consumer-resource associations organize into trait profiles that reflect the general vertical structure of the food web, as well as identify groups of limited sets of highly interacting traits. Finally, we discuss the implications of the findings for generating comprehensive and adaptive food webs.

The Hungarian meadow viper (Vipera ursinii rakosiensis) is an endangered subspecies of Vipera ursinii, which faces high predation pressure, partially due to avian species. To create a systematic method for estimating the measure of predation pressure, we developed a geometric morphometric approach to identify both undamaged and damaged vertebrae of snake species found in Hungarian meadow viper habitats from raptor feeding remains. We used linear discriminant analysis with a reference material of vertebrae from identified snake species as training data. We also tested its efficiency by predicting the identification results of different simulation levels based on vertebra completeness. We practiced this method on vertebrae of unknown species of snakes obtained from nests and pellets of short-toed snake eagles (Circaetus gallicus, n = 9), common buzzards (Buteo buteo, n = 14) and Montagu's harriers (Circus pygargus, n = 3). The identification approach showed high accuracy, even in the case of missing landmarks to some extent. We identified vertebrae remnants of Natrix natrix (n = 172, 83.9%), Coronella austriaca (n = 10, 4.9%) and V. u. rakosiensis (n = 23, 11.2%). Both, the reptile specialist C. gallicus and the generalist B. buteo proved to be preying on V. u. rakosiensis, while samples of C. pygargus did not contain any snake remains despite of previous observations of V. ursinii predations. Our approach is applicable for other studies and taxa as well, therefore can be a practical tool for classification of incomplete vertebrae, which is otherwise hardly identifiable. Furthermore, it could be applied to help estimate predation pressure on endangered snake species.

As the importance of both the high seas and gelatinous zooplankton is continuously revealed, it is important to document basic interactions. Physalia are venomous siphonophores, commonly called ‘Man of War’ or ‘Bluebottles’, that use a gas filled float to sail the high seas. Despite being the most conspicuous member of the neustonic ecosystem (the ecosystem at the open ocean's surface), little is known about its life history nor its ecosystem contributions. Herein, two ant species, Solenopsis cf. geminata and Iridomyrmex cf. anceps, were observed foraging on beached colonies of Physalia cf. utriculus in Guam, Micronesia. Ants explored fresh colonies with untriggered stinging cells, yet only disassembled and transported partially dry or degraded colonies. Observations like this improve the understanding of cross-ecosystem dynamics between the coastal and neustonic ecosystem, island trophic structures, and the contribution of gelatinous zooplankton.

Physiological regulation of internal body composition is critical for the fitness of many organisms. Arthropods are abundant around the world and exhibit incredible diversity, yet little is known about how these groups differ in body composition or the mechanisms behind internal changes in chemistry over time. The goal of this study was to examine the lipid and protein content of several common terrestrial arthropod orders, and to determine if this macronutrient composition changes across the season. Additionally, we describe relationships between arthropod body measurements and lipid, protein, and overall dry mass. Arthropod total length and width strongly correlated with macronutrient masses, while other body measurement relationships varied considerably. As expected, arthropod orders varied significantly in both lipid and protein content. Within-order lipid and protein content also varied significantly across the season. These results demonstrate that the nutritional content of invertebrates may fluctuate over time, likely due to shifts in size, ontogeny, and environmental conditions. Understanding the mechanisms behind these changes will be important for unraveling the evolutionary history of these groups as well as the roles they play in surrounding food web structure.

Kleptoparasitism, the theft of food from another individual, is an important interspecific interaction that can have consequences for animal fitness, predation rates, and species' abundance. Similarly, loss of food to fear effects and interspecific interactions can influence energetic costs and consumption rates. Due to their smaller body size and predominantly solitary nature, cheetahs (Acinonyx jubatus) are particularly prone to negative, direct interactions with competing carnivores, and they frequently lose kills to apex predators. However, trophic interactions with other species may have been underreported in the literature. Here, we document anecdotal interactions between cheetah and baboon (Papio spp.) species, across multiple sites in Africa, where baboon troops chased cheetahs off their kills and, in some cases, fed on the remaining carcasses. Given the widespread distribution, and relatively high densities of baboon species across sub-Saharan Africa, we hypothesise that these interactions are likely to be underrepresented in the literature. Since cheetah already experience high levels of competition with apex predators, particularly in South African fenced reserves where competing carnivores are often stocked at densities approaching, or in some cases exceeding, carrying capacity, additional competition and the loss of prey to baboons could further increase predation rates and have implications for reserve management. Baboons are often defensive around large carnivores. As such, interactions with cheetahs are likely to be motivated primarily as a defensive strategy. We encourage further research into food loss, kleptoparasitic behaviour and other competitive interactions between cheetah and Papio species.

Island ecosystems provide valuable opportunities to explore some aspects associated with resource partitioning. While some ecological studies have suggested that island populations could keep a narrow dietary niche due to limited food sources, recent studies challenge this long-held belief for insular lizards. Herein, we evaluated the trophic web of the lizard community from María Cleofas Island in the Gulf of California, Western Mexico. We quantified the inter-individual diet variation for each lizard species, compared prey diversity between species, and analyzed any potential variations across different years. Our research revealed a wide variety of arthropods within the stomach contents of the lizards, regardless of their foraging strategy and habitat use. Our results also showed the inclusion of prey items that have not been previously reported in studies focusing on mainland-island populations. For example, we observed Anolis nebulosus predating cockroaches, hemipterans, and isopods. We observed differences in prey groups among lizard species, highlighting the broader niche of Anolis nebulosus, Phyllodactylus cleofasensis, and Aspidoscelis communis, as well as the narrowest trophic niche of Ctenosaura pectinata. Our research on the lizard community of María Cleofas Island has not only demonstrated the wide dietary diversity among species but has also expanded our understanding of trophic relationships in island ecosystems, with important implications for ecological studies.

Host-parasite interactions and host susceptibility are key traits in understanding trophic energy transfer, nutrient movement and general macro-ecoevolutionary dynamics of mistletoe systems and plant-plant interactions. This research investigates host susceptibility and size-dependent interactions of the mistletoe Phoradendron quadrangulare, a widely distributed species, on Guazuma ulmifolia. We studied the interplay between mistletoe load and host tree size, while also exploring the allometric relationship between host branch size and mistletoe size. A field surveys on 67 trees revealed varying mistletoe loads, with most trees showing no occurrence of P. quadrangulare. Parasitized trees had significantly larger diameters at breast height (DBH) than non-parasitized trees. The susceptibility of host trees to mistletoe parasitism increased with increasing DBH, indicating a positive relationship between host size and mistletoe prevalence. Furthermore, mistletoe stem diameter was found to be influenced by the diameter of the host branch suggesting that larger host trees provide more substrate for larger-sized parasites and surface area for mistletoe colonization, potentially contributing to the parasite's survival and prevalence. This study also highlights the importance of host size in mistletoe presence and performance and provides insights into the broader eco-evolutionary dynamics and conservation strategies needed to conserve mistletoes, an often-underappreciated keystone taxa.

Predator-prey interactions are fundamental to understand how energy flows in trophic food webs. Frogs play a central role in Neotropical food webs, as they are prey and predators for many animals, including other frogs. In particular, species of the genus Leptodactylus have been reported as predators of several frogs, thus being a model to understand the ecological patterns of predator-prey relationships. Therefore, we reviewed the literature for records of anurophagy between 1964 and 2023, assessed the size relationships of these interactions, and the spatiotemporal patterns of these reports. Descriptions of anuran predation by Leptodactylus spp. have increased substantially in recent decades, especially after 2002. We found a positive relationship between prey and predator sizes, despite it we found that smaller Leptodactylus species consumed proportionately larger preys than larger species, while larger species consumed frogs with a greater variation in body size. The species of the genus Leptodactylus preyed more on leptodactylid frogs, probably due to their similar habitat use. Records have also included frogs from other families and even cannibalistic events have been reported. Most published articles describing these interactions lack information such as predator and prey sizes, accurate species identification, anuran developmental stage, antipredator strategies, and microhabitat information. Consequently, we suggest that future reports and studies must include this complementary information that will improve our overall understanding of anuran predator-prey relationships.

Predators impact prey directly, through consumption, and indirectly, through non-consumptive effects that modify prey physiology and behavior in ways that affect survival and reproduction. Non-consumptive effects (NCEs) are well documented across prey taxa in response to different predator cues. However, for most prey species, both the mechanisms underlying NCEs and the impacts of NCEs on broader ecological processes are poorly understood. We addressed these knowledge gaps for an aphid prey species (Myzus persicae) by studying dispersal, in-leaf feeding behavior, and plant virus transmission in response to chemical cues deposited by a walking predator (Hippodamia convergens), a non-predator, non-competitor (Drosophila melanogaster), and an artificial feeding deterrent (2% mineral oil). We used this approach to better understand the specificity of M. persicae responses to chemical footprints of threatening and non-threatening organisms, as well as the magnitude of behavioral responses relative to a known deterrent. We found that chemical footprints deposited by H. convergens stimulated M. persicae to disperse from a suitable host (Brassica napus) at a rate equivalent to the 2% mineral oil positive control, while footprints of D. melanogaster did not modify M. persicae dispersal. Through electrical penetration graphing (EPG) recordings, we found that mineral oil stimulated aphids to make more probes, but footprint treatments did not significantly modify feeding behavior. In mesocosm-based virus transmission assays, H. convergens footprints and 2% mineral oil also stimulated increased dispersal, but this did not translate into increased transmission of turnip mosaic virus. We identified components of H. convergens and D. melanogaster footprints using gas chromatography and mass spectrometry and found that H. convergens footprints are chemically similar to footprints of related Coccinellidae, but distinct from D. melanogaster footprints. Our results provide evidence of specificity in M. persicae responses to predator footprints, which may help this prey species avoid costly dispersal behavior in response to cues from non-predators. We also provide ecological context by demonstrating that increased dispersal in response to predator cues does not always lead to increased virus transmission, as previously assumed, particularly when in-leaf feeding behaviors underlying virus acquisition do not change in response to predator cues.