Generalist Feeding Strategy Research Articles

Genome-Wide Gene Birth-Death Dynamics Are Associated with Diet Breadth Variation in Lepidoptera.

Comparative analyses of gene birth-death dynamics have the potential to reveal gene families that played an important role in the evolution of morphological, behavioral, or physiological variation. Here, we used whole genomes of 30 species of butterflies and moths to identify gene birth-death dynamics among the Lepidoptera that are associated with specialist or generalist feeding strategies. Our work advances this field using a uniform set of annotated proteins for all genomes, investigating associations while correcting for phylogeny, and assessing all gene families rather than a priori subsets. We discovered that the sizes of several important gene families (e.g. those associated with pesticide resistance, xenobiotic detoxification, and/or protein digestion) are significantly correlated with diet breadth. We also found 22 gene families showing significant shifts in gene birth-death dynamics at the butterfly (Papilionoidea) crown node, the most notable of which was a family of pheromone receptors that underwent a contraction potentially linked with a shift to visual-based mate recognition. Our findings highlight the importance of uniform annotations, phylogenetic corrections, and unbiased gene family analyses in generating a list of candidate genes that warrant further exploration.

Elucidating dietary secrets of the Blue‐headed Macaw, Primolius couloni (Sclater, 1876), through citizen‐sourced photographs

AbstractDietary data are vital for understanding species' resource requirements and ecological roles and supporting conservation efforts. The Blue‐headed Macaw, Primolius couloni, is a vulnerable and endemic species in the Amazon. Due to their rarity, elusive nature, complex forest canopy habitat, and occurrence in remote areas, we minimally know their dietary habits. To address this gap, we analysed photographs of Blue‐headed Macaws posted on wildlife‐focused social media platforms, specifically targeting images that capture foraging behaviour on plants. Photographs depicting the same foraging were included only once, and those where the plants were not identified were discarded. By doing so, we identified 36 distinct foraging events (or photos), primarily taken between July and October, concentrated in specific locations in Peru and Brazil, a potential seasonality in foraging. We documented 27 food plant species and items such as nectar (n = 9 photos), pulp (8), seeds (7), buds, bark (5 each), aril, and leaves (n = 1 photo each). Notably, floral resources, including nectar, are a potentially important food in the driest months. Using Levin's Index (Ba), we identified a broad dietary niche, indicating a generalist feeding strategy with a wide variety of plant species (Ba = 0.69) and food items (Ba = 0.88). Additionally, the study revealed interactions such as florivory, seed predation, bark consumption, and potential mutualistic roles like pollination and seed dispersal. Our photo‐centric approach here expanded the known dietary spectrum of the Blue‐headed Macaw from four to 31 plant species, offering new insights for conservation strategies. We recommend the preservation of identified food plants and suggest using these data to inform habitat restoration efforts that support the macaws' dietary needs and ecological functions. Future research should focus on continuous monitoring of these food plants to deepen our understanding of seasonal foraging trends and ecological interactions and refine conservation approaches.

Trophic niche partitioning among non-native fish species coexisting in a Colombian high Andean reservoir

The introduction of non-native species to a new environment poses a threat to local biological diversity, causing instability in the functioning of the ecosystem. The ecological effects caused by these species have been scarcely documented in the Magdalena basin. By studying predator–prey interactions, we characterized the trophic niche of three non-native species (Cyprinus carpio, Micropterus salmoides, and Oncorhynchus mykiss) that dominate a high Andean reservoir in the Magdalena basin. This study allows us to understand their specific feeding behaviors and how these behaviors facilitate their establishment in the reservoir. We evaluated the diversity of the prey they consume, their feeding strategy, and possible differences in the feeding scheme. Forty individuals were analyzed, with the highest representation of M. salmoides with 17 individuals, followed by C. carpio (13 individuals), and finally O. mykiss with 10 individuals. We identified twenty categories of food as prey for these species, with aquatic invertebrates and vegetation material being the predominant prey. The analysis of stomach contents in these samples suggested that they are representative for determining specialized or generalist feeding strategies. There were no differences in the number of prey items consumed by these three species. The analysis revealed that the feeding strategies are specific for each species. There was no overlap in the diet of C. carpio with the other two species, however, the composition of the diet is similar between M. salmoides and O. mykiss. Analyzing the diet of these non-native fish provides a useful tool for describing trophic interactions in this aquatic environment. Our results contribute information on the existing interactions amongst non-native species in the Magdalena basin, which is important for the development of strategies to manage and mitigate their impact.

Fish trophic network in karst streams from Brazilian Pantanal headwaters

Abstract Trophic interactions have been a long-standing field of interest in ecology, helping to understand the relationships between organisms and how ecosystems function. In this study, we describe the trophic relationships of fish from karst environments in headwater streams of the upper Paraguai River basin. We analyzed the stomach contents of 81 fish species from the Serra da Bodoquena, calculated the metrics associated with the trophic network, incorporating the body size component in the analyses, and evaluated the participation of each species in network/module connectivity. The analyzed community trophic organization was based mainly on autochthonous items which were the most consumed items for about 30% of fish species. The trophic network showed a modular pattern without nestedness or specialization. However, nestedness was significant within each module, demonstrating a hierarchical compound topology (i.e., species with few connections interacted with subsets of the pairs of more connected species within each module). We also found a relationship between network connectivity and fish body size, in which small species tend to connect modules through generalist feeding strategies. Thus, we demonstrated a still little-known role of small species in fish trophic networks, and how trophic segregation occurs in a highly diverse community from Pantanal headwater streams.

High microplastic and anthropogenic particle contamination in the gastrointestinal tracts of tiger sharks (Galeocerdo cuvier) caught in the western North Atlantic Ocean

Few studies have documented microplastics (<5 mm) in shark gastrointestinal (GI) tracts. Here, we report microplastic contamination in the tiger shark (Galeocerdo cuvier), an apex predator and generalist feeder, at several different life stages. We examined seven stomachs and one spiral valve from eight individuals captured off the United States Atlantic and Gulf of Mexico coasts (eastern US) and conducted a literature review of publications reporting anthropogenic debris ingestion in elasmobranchs. Specimens were chemically digested in potassium hydroxide (KOH) and density separated using calcium chloride (CaCl2) before quantifying and categorizing suspected anthropogenic particles (>45 μm) by size, morphology, and colour. Anthropogenic particles were found in the stomachs and spiral valve of all sharks. A total of 3151 anthropogenic particles were observed across all stomachs with 1603 anthropogenic particles observed in a single specimen. A subset of suspected anthropogenic particles (14%) were chemically identified using Raman spectroscopy and μ-Fourier Transform Infrared spectroscopy to confirm anthropogenic origin. Overall, ≥95% of particles analyzed via spectroscopy were confirmed anthropogenic, with 45% confirmed as microplastics. Of the microplastics, polypropylene (32%) was the most common polymer. Diverse microparticle morphologies were found, with fragments (57%) and fibers (41%) most frequently observed. The high occurrence and abundance of anthropogenic particle contamination in tiger sharks is likely due to their generalist feeding strategy and high trophic position compared to other marine species. The literature review resulted in 32 studies published through 2022. Several methodologies were employed, and varying amounts of contamination were reported, but none reported contamination as high as detected in our study. Anthropogenic particle ingestion studies should continue in the tiger shark, in addition to other elasmobranch species, to further understand the effects of anthropogenic activities and associated pollution on these predators.

Feeding ecology of the African cuttlefish Sepia bertheloti (Cephalopoda: Sepiidae) in western Africa

The African cuttlefish, Sepia bertheloti, is a commercially exploited cephalopod in two productive system areas off West Africa. However, there is a lack of information on its feeding ecology, making it difficult to describe its ecological role (Morocco and Guinea-Bissau). In the present study, we analyse the gastric contents of 1.114 individuals, collected between July 2018 and January 2020 using the traditional analysis of stomach contents. A total of 65 and 49 prey items were identified as part of the diet of Moroccan and Guinean African cuttlefish, respectively. The sample size was evaluated using species cumulative curves and the methods used to describe the diet were the frequency of occurrence, number, and weight. Our results suggest that S. bertheloti does not present differences in diet between sexes or areas, although significant differences were observed in terms of prey abundance, richness, and diversity of species. According to the taxonomic groups, crustaceans were the most abundant prey taxa, followed by fish and cephalopods. Amphipods (Gammarus sp.) were the prey that showed the greater importance of occurrence in the diet at both study areas, showing a strictly benthic feeding behaviour. Niche breadth was evaluated using Levin’s index, indicating that S. bertheloti is an omnivorous species (Trophic level ∼3.6) with a heterogeneous diet and without a marked generalist or specialist feeding strategy.

Functional and temporal facets of predation by marsh frogs across the aquatic–terrestrial ecotone of ponds and implications in the context of biological invasions

Abstract Freshwater vertebrate predators can exert trophic control over aquatic and littoral communities. Among these predators, post‐metamorphic anurans exhibit a biphasic trophic spectrum by foraging in both terrestrial and aquatic habitats. Many studies have described their diet through the classical taxonomic classification of prey. However, these singular diet habits imply a complex, time‐dependent, realised trophic niche in which predation pressure occurs over many consumers that fill diverse functional roles throughout the aquatic and terrestrial interface of ponds. Among anurans, marsh frogs (Pelophylax ridibundus) have been introduced outside their range in many countries and are now invading nationwide areas, particularly in western Europe. Focusing on their foraging specificities will therefore further the understanding of the trophic role of these alien taxa in pond environments that are highly colonised. We collected stomach contents from 761 marsh frogs from introduced populations in 19 ponds in southern France once a month over 4 months of their active period in the spring. The populations of marsh frogs were studied in a geographic area that was devoid of native water frogs and their origin tracks back as far as south‐eastern Europe (i.e., more than 1,000 km from the studied sites, as evidenced previously by genetic analyses). Marsh frogs exhibited generalist and opportunistic feeding strategies. The trophic niche was strongly asymmetrical and broader in the terrestrial environment than in the aquatic environment. However, predation occurred in communities of large freshwater macroinvertebrates and amphibians. Whereas the composition of the terrestrial diet exhibited strong seasonal variations, predation pressure was continuously exerted on the same aquatic organisms over time. Primary consumers and consumers at higher trophic levels frequenting aquatic benthic, vegetated, pelagic, and surface microhabitats were preyed upon, underlying the multidimensional extent of the predation spectrum. The diversified feeding strategies of alien marsh frogs highlight the extent of potential ecological control by predation on pond communities. Because of their wide trophic niche, they exert predation pressure on most pond organisms, triggering possible top‐down control of the overall aquatic communities. Our results show that the integration of the functional traits and microhabitats of consumed prey may aid in a better understanding of how predation by anurans may target specific components of pond communities. More particularly, this study raises concerns about the predatory role of introduced anurans in the context of biological invasions.

Rare and Hungry: Feeding Ecology of the Golden Alpine Salamander, an Endangered Amphibian in the Alps.

Amphibians are considered critical species in the nutrient flow within and across ecosystems, and knowledge on their trophic ecology and niches is crucial for their conservation. For the first time we studied the trophic ecology of the rare and endemic Salamandra atra aurorae in a mixed temperate forest in northern Italy. We aimed to define the realized trophic niche, investigate the prey selectivity and explore possible levels of individual specialization. In summer 2022 we obtained stomach contents from 53 salamanders by stomach flushing and prey availability using pitfall traps. We used the Costello graphical method to analyse the realized trophic niche, and the relativized electivity index to study prey selectivity. Our results show that the Golden Alpine salamander adopts a generalist feeding strategy with positive selection of few prey categories (e.g., Myriapoda, Hymenoptera except Formicidae). Food preference seems to be driven by size, movement ability and chitinization of the prey. A high degree of inter-individual diet variation, modularity and clustering was found, describing a scenario that can be framed in a Distinct Preference model framework. This study gives new insights on the trophic ecology of the Alpine salamander complex, whose subspecies appear to adopt similar feeding strategies.

Insight into the trophic niche and prey contribution in the diet of Lutjanus griseus (Linnaeus, 1758) captured by artisanal fishing fleet in the central and southwest Gulf of Mexico

Lutjanus griseus is a common species for fisheries of the Gulf of Mexico, and it is an effective vehicle to transport energy from low to top trophic levels in the ecosystem. The management of fish populations is based on the modeling and prediction of abundances. To accomplish this, trophic ecology results allow the understanding of habitat use and population expansions. To increase the knowledge in the trophic ecology of L. griseus, this study described its trophic niche, diet composition, and the prey contribution in the formation of muscle tissue. Results showed that the trophic niche in Veracruz was wider than in Campeche, this related to the consumption of prey in different habitats, coral reefs areas in Veracruz and seagrass beds in Campeche. According to the δ13C y δ15N values, in both regions the crustaceans were the most important group in the contribution of muscle tissue, however, it contrasted with the stomach content results, which suggested that the diet in Campeche was mainly composed of crustaceans, and in Veracruz of fishes. This difference could be related to the snapper’s movements, as they can be found in sea bottoms covered with seagrass, with high abundance of crustaceans, and sea bottoms composed of coral reefs with high diversity of fishes and other preys. Results highlight the generalist and opportunistic feeding strategy of L. griseus, this strategy allowed its population expansion to the north, consuming the available food source in the different habitats it occupied.

Density‐dependent processes and population dynamics of native sculpin in a mountain river

AbstractUnderstanding the processes governing population dynamics is important for effective conservation and environmental management. Disentangling the relative role of density‐dependent versus density‐independent processes on population dynamics is often made difficult by the inability to control for abiotic or biotic factors, but long‐term datasets are invaluable in this pursuit. We used a 14‐year dataset from the Logan River, Utah, to assess long‐term trends in abundance and evidence of density‐dependent and density‐independent effects on population dynamics of Paiute sculpin (Cottus beldingii) across six sites. Additionally, we evaluated the feeding ecology of sculpin over 4 years. Sculpin densities generally increased from upstream to downstream, and the annual per capita rate of increase was negatively and significantly correlated with sculpin density at four of six sites. We observed a negative relationship between total gut content and sculpin density but did not observe a negative relationship between relative condition and density. Sculpin displayed a generalist feeding strategy, and interannual differences in diet composition appeared to be influenced by interannual differences in flow, particularly years with higher magnitude flow. The observed spatial patterns in sculpin abundance throughout the watershed matched those of invasive brown trout (Salmo trutta), the top piscivore in the Logan River, and likely represent affinities for the suite of ecological conditions associated with downstream sections of the Logan River. Our results suggest that sculpin populations are regulated largely by density‐dependent processes and match those from other studies on sculpin population dynamics including a range of species and habitats that differ vastly in abiotic conditions.

Feeding biomechanics reveals niche differentiation related to insular gigantism.

Insular gigantism is an evolutionary phenomenon whereby small animals become bigger on islands compared to their mainland relatives. The abundance of insular giant taxa in the fossil record suggests the presence of a universal "giant niche" present on islands, with resource limitation as a potential driver for this process. However, insular habitats are ecologically diverse, suggesting that island taxa adopt different survival strategies, including adaptations for foraging behaviors. Here, we used finite element analysis to evaluate insular feeding niche adaptations in some of the most extreme examples of insular gigantism: Mediterranean giant dormice. We calculated stress, strain, and mechanical advantage during incisor and molar biting for 3 extinct insular giant species (Leithia melitensis, Hypnomys morpheus, and H. onicensis), an extant giant (Eliomys quercinus ophiusae), and their extant non-giant mainland relative, the generalist-feeder Eliomys quercinus. Our results show that dietary adaptations vary between giant taxa on different islands, and can occur relatively rapidly. Furthermore, the functional mandibular morphology in some insular taxa indicate adaptations moving away from a generalist feeding strategy toward greater trophic specialization. We show that the "insular giant niche" varies between islands and across time periods, arguing against a universal ecological driver for insular gigantism in small mammals.

Diet and Feeding Ecology of the Invasive &lt;i&gt;Gambusia holbrooki&lt;/i&gt; (Teleostei: Poeciliidae) in Lotic and Lentic Habitats (Northwestern Part of Turkey)

Received October 13, 2021; revised April 22, 2022; accepted August 15, 2022Abstract—In order to understand the success of the invasion of a non-native fish, it is important to determine its fundamental competition characteristics such as its tolerance to habitat differences and feeding plasticity. This study aimed to determine the invasive characteristics of Gambusia holbrooki Girard, 1859 by investigating the diet and feeding ecology of this non-native fish inhabited in lotic and lentic habitats. A total of 164 G. halbrooki specimens (SL 1.4–4.3 cm) were investigated from the lotic habitats, while 101 (SL 1.6–3.3 cm) ones were from the lentic habitats. The food spectrum of the fish in lotic habitats was composed of 11 food items predominantly of the Diptera (80.9, MI%) and Plant (11.8, MI%). In lentic habitats, the species consumed 10 different food types, and Diptera (96.0, MI%) was followed by the low values of zooplankton groups (Cladocera; 2.2, MI% and Copepoda; 0.8, MI%). The fish that inhabited both lotic and lentic habitats have shown a generalist feeding strategy; while the importance of each food item in the diet indicated the generalization, Diptera presented with high values was the evidence of a relatively narrow niche of the fish in both habitats. An ontogenetic shift was observed in the diet of G. holbrooki and while the diet of juveniles was more limited, the diversity and sizes of food items consumed have increased in parallel with the increase in the size of the fish. With these results, it was thought that G. holbrooki could show a food competition with native fish species in the region by feeding mainly on Diptera, which is also an important food source for most of the native fishes and their young individuals.

Diet composition and resource overlap of sympatric native and introduced salmonids across neighboring streams during a peak discharge event.

Species assemblages composed of non-native and native fishes are found in freshwater systems throughout the world, and interactions such as interspecific competition that may negatively affect native species are expected when non-native species are present. In the Smith River watershed, Montana, rainbow trout were introduced by 1930. Native mountain whitefish and non-native rainbow trout have presumably occurred in sympatry since the introduction of rainbow trout; however, knowledge about how these two species compete with one another for food resources is sparse. We quantified diet compositions of rainbow trout and mountain whitefish in the mainstem Smith River and in a tributary to the Smith River-Sheep Creek-to determine the degree of overlap in the diets of mountain whitefish and rainbow trout in the Smith River and between the mainstem Smith River and a tributary stream. Rainbow trout and mountain whitefish had generalist feeding strategies, which probably contribute to the amicable coexistence of these species. Diet overlap between rainbow trout and mountain whitefish was high (Pianka's index value = 0.85) in the Smith River and moderate in Sheep Creek (Pianka's index value = 0.57). Despite overlap in diets, some resource partitioning may alleviate resource competition (e.g., rainbow trout consumed far more Oligochaeta than mountain whitefish but fewer Brachycentridae and Chironomidae). Diet composition of rainbow trout and mountain whitefish did not differ greatly between the Smith River and Sheep Creek. Prey categories most commonly used by mountain whitefish at the population and individual levels (i.e., Ephemeroptera and Trichoptera) are sensitive taxa and many species within these orders have experienced extinctions and population declines. Therefore, future changes in resource availability or competition could be of concern.

Cognitive Foraging Enrichment (but Not Non-Cognitive Enrichment) Improved Several Longer-Term Welfare Indicators in Bottlenose Dolphins.

Bottlenose dolphins are the most common cetacean kept globally in zoos and aquaria (hereafter zoos), and are gregarious animals with a mostly opportunistic, generalist feeding strategy in the wild. In zoos, they have limited to no opportunities to express natural foraging behaviours as they receive their daily food ration of dead fish in a series of training sessions. Enrichment provision has increased in recent years, but items are still predominantly simple and floating in nature, and do not always target the animals' problem-solving or food-acquisition behaviours. These discrepancies run concurrently with the intense debate about dolphin welfare in zoos and how to improve it. The current study used a within-subject design on 11 bottlenose dolphins at Kolmårdens Djurpark and measured how several welfare indicators differed between two treatments of "cognitive" and "non-cognitive" food-based enrichment. The treatments were provided on an alternating basis for eight consecutive weeks: during cognitive enrichment weeks, the animals received items which stimulated their problem-solving and foraging behaviours, and during non-cognitive enrichment weeks, they received simple items paired with fish (to eliminate bias due to food value). Data were taken related to several multidisciplinary welfare parameters during enrichment provision and training sessions, and to activity budget behaviours throughout the week. During the cognitive as opposed to non-cognitive enrichment weeks, the dolphins engaged more with the enrichment, were more motivated to participate in training sessions and performed less anticipatory and stereotypic behaviours, suggesting that cognitive enrichment improved several indicators of bottlenose dolphin welfare. Valuable lines of further investigation would be to understand how individual differences and different types of cognitive enrichment impact potential welfare benefits. Our results suggest that enrichment items promoting cognitive foraging behaviours may improve dolphin welfare, and therefore zoos might prioritise giving cognitive enrichment to this species as well as considering the same for other species with similar cognitive skills and foraging ecologies.

Biological invasion: evidence from a tropical reservoir (Eleiyele, South West Nigeria

The encroachment of freshwater territories by invasive species is a global issue with its associated co-existence, displacement and facilitation of native species. The blackchin tilapia, Sarotherodon melanotheron is one of the most successful biological invasive species. Data on its apparent ecological consequences on native species are rare in Nigerian inland waters. Based on stomach contents analyses, diets, feeding strategies, and dietary niche breadths of two sympatric invasive S. melanotheron and native Nile tilapia Oreochromis niloticus populations in a tropical domestic water supply were assessed for possible convergence. Both species exhibited generalist feeding strategies subsisting mostly on algae but fish eggs and larvae were conspicuous preys of S. melanotheron. Dietary niche of S. melanotheron was wider than that of O. niloticus. Dietary niche overlap was high and significant between these sympatric species. These findings imply that competitive feeding interactions-including predations on vulnerable early life stages may potentially promote invasion success of S. melanotheron in Eleiyele Reservoir.

The impacts of seasonal variation and climate on food utilization in a population of critically endangered cotton-top tamarins (Saguinus oedipus) in Colombia: A 22-year longitudinal study.

To examine how precipitation patterns and climate change impact feeding choices made by a population of critically endangered cotton-top tamarins (Saguinus oedipus), we examined 22 years of feeding data (1999-2020) from 21 groups collected at Parque Natural Regional Bosque Seco El Ceibal Mono Tití in Santa Catalina, Colombia. We describe the diet and examine the role of seasonal rainfall and annual variation in rainfall on diet. Rainfall is highly seasonal (mean annual rainfall 1562 mm [range 940-2680 mm]) with a dry, early rainy, and late rainy season in each year. Over 80 species of plants formed part of the fruit, nectar, and exudate components of the diet. Fruits, although available year-round, were more commonly available and consumed during the late rainy seasons (August-November). Exudates were consumed more frequently in the dry season (December-March) and invertebrate consumption was stable across the year. Nectar feeding from a single species (Combretum fruticosum) peaked in November. Rainfall varied over the years, with 13 years exceeding the 99% confidence intervals for mean rainfall. Ten of these extreme years (both drought and extremely wet) occurred in the last 11 years. Fruit consumption did not vary between extreme and average years, but cotton-top tamarins consumed more invertebrates and exudates in wet years. Presently, cotton-top tamarins appear to be able to cope with these extreme variations in rainfall due to their highly varied diet. However, the forests that these primates depend upon for survival are threatened by human exploitation making it critically important to maintain a generalist feeding strategy for survival as many fruiting trees that compose a large proportion of the diet are removed. As conservation efforts continue, plant species consumed by cotton-top tamarins provide useful data when selecting species for habitat restoration programs.

Feeding ecology of the endangered Apennine Yellow-bellied Toad (Bombina pachypus) in central Italy

Anurans are generalist opportunistic consumers, but many species show some degree of diet specialization. Within populations, individuals may specialize in specific dietary resources (individual specialization). Indeed, generalist populations may be composed of individuals using the whole range of available resources or of diverse individuals exploiting specific food items. Based on the niche variation hypothesis (NHV), an increase in population niche width may be related to a higher incidence of individual specialization. We analyzed the feeding ecology of the endangered Apennine Yellow-bellied Toad ( Bombina pachypus (Bonaparte, 1838)) in central Italy. This species showed a generalist feeding strategy, wide trophic niche, high individual generalization, and a predominant use of terrestrial resources. The study species inhabits seasonal habitats determining variation in food availability and diversity, and this may have driven toads to be unselective and consume almost any encountered palatable item. The absence of sexual size dimorphism may explain the absence of trophic differentiation between sexes. The analysis of individual feeding traits revealed a week's degree of individual specialization positively correlated to niche width, partly supporting the NHV. The obtained information can be used for the implementation of effective conservation strategies of locally imperilled species, especially those breeding in temporary ponds.

Linking agricultural practices to lizard trophic behaviour: An ecological approach

Among intensive agricultural practices, pesticides, mowing, and heavy agricultural machineries have become an important tool to maximize harvesting and secure animal husbandry. However, they are also cause of agricultural ecosystem decline, often leading to degradation of key micro-habitat features for many species, higher predation risk and lower food availability. We investigated the diet and foraging ecology of the Italian wall lizard in agricultural areas to determine whether different management practices (conventional, organic, and control) can affect (i) the structure of the trophic niche of the species; (ii) prey diversity, the degree of individual specialization, and the overall population feeding strategy; (iii) lizards' health status. Faecal pellets were collected for diet composition analyses, while prey diversity in the environment was estimated by placing adhesive traps. Lizards' body condition did not differ among management type although males from control field resulted slightly larger than those from conventional and organic areas. The species showed a generalist (conventional and organic areas) and mixed (control area) feeding strategy with a preference for coleopterans. Although a different prey diversity was found in control areas compared to organic and conventional ones, diet composition and the importance of specific food items was similar among management types. This may suggest that management activities may have affected the overall prey availability and indirectly influenced lizard trophic behaviour. Our study provides a comprehensive knowledge on the feeding ecology of P. siculus in managed habitats, which may have useful implications for the overall conservation of lizards in agricultural environments.

Sexual dimorphism and static allometry in the South African scorpion Opistophthalmus karrooensis

Sexual dimorphism in scorpions is generally retrieved for a similar subset of body parts and is presumed to result from alternative types of selection operating on homologous structures in each sex. Even so, investigations which use static allometry as a method for testing specific hypotheses relating to selection remain limited. Sexual dimorphism in the majority of South African scorpion species is poorly investigated, especially in the genus Opistophthalmus, of which the endemic Karoo burrowing scorpion O. karrooensis is nearly completely data deficient. The current study investigates patterns of sexual dimorphism and static allometry in O. karrooensis, based on external morphology. Following character scaling on carapace length, patterns of sexual dimorphism in this species indicate the elongation of male appendages (pedipalp segments, legs, pectines, metasoma, and telson), while females display wider bodies and wide, thick pedipalp segments. These patterns possibly point to an enhanced reproductive output and parental care in females, coupled to a sedentary lifestyle and generalist feeding strategy. Conversely, the male morphology is likely adapted for greater vagility, but should also function during mate-trailing and sexual interactions. In line with these explanations, the body parts in both sexes indicate static allometric patterns pointing (at least in part) to the potential influence of either natural or sexual selection, but further reveal the possibility of intense selection on a number of body parts. Taken together, the selective forces which shape scorpion morphology may be complex, relating to multiple functions of body parts and life-history differences between the sexes.

COMPOSICIÓN Y ESTRUCTURA DE LA DIETA DE PAVO OCELADO (MELEAGRIS OCELLATA) EN UN TERRITORIO AGROFORESTAL, CAMPECHE, MÉXICO

&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;: The Ocellated Turkey is a priority species because of its endemic status and being a strategic resource for local communities. An assessment of the state of its populations in the Yucatan Peninsula between 1980 and 2000 reports that the abundance decline is correlated with its weak dispersion capacity, habitat degradation, and availability of food resources. However, detailed information on its habitat requirements and trophic ecology is still very limited. Therefore, qualitative and quantitative information on the food resources consumed by &lt;em&gt;M. ocellata&lt;/em&gt; is essential for the implementation of management strategies aimed at promoting the conservation of the species. &lt;strong&gt;Objective:&lt;/strong&gt; In an agroforestry territory managed under the Mexican scheme of Units for Wildlife Conservation (UMA), the composition and structure of the Ocellated Turkey male diet were determined. &lt;strong&gt;Methodology:&lt;/strong&gt; The study site corresponds to UMA Las Flores, Campeche, Mexico. It is a communally owned agroforestry territory run by Mennonite colonies whose primary economic activities are soybean, sorghum, and maize agriculture. It has an area of 9600 ha, four thousand are farmlands and the rest of forest cover. The taxonomic composition of the male diet was evaluated analyzing food content present in the upper digestive tract (crop and gizzard) of 72 samples of male birds hunted during the breeding season (January to April 2019). The Relative Importance Index was estimated to quantitatively assess the importance of each food component and the Levins Index assessed the degree of specialization in the diet. &lt;strong&gt;Results: &lt;/strong&gt;According to the frequency of occurrence and abundance of the food components, we found that the male Ocellated Turkey presented a generalist and opportunistic feeding strategy; the stomach contents consisted of resources from the field crops, whose dietary composition was granivorous. Diet composition was based on the consumption of 39 vegetables belonging to 20 families of 12 orders. Of the six established food categories, the seeds registered the highest value with 94.49% of the total dry weight, being corn, sorghum, and a wild specie belonging to the Convolvulaceae family the most significant resources in the diet. &lt;strong&gt;Implications:&lt;/strong&gt; Our results help to determine the importance of agroforestry systems to meet food requirements and evaluate the trophic dynamics of the Ocellated Turkey, as well as the plasticity of the species to use food resources in different scenarios in space and time throughout its distribution range. &lt;strong&gt;Conclusion:&lt;/strong&gt; Information on the composition and abundance of food resources consumed by &lt;em&gt;M. ocellata&lt;/em&gt; males in an agroforestry system managed under UMA's Mexican scheme is important for understanding and redefining habitat requirements and trophic niche amplitude, to implement management strategies that promote the increase of their wild populations and sustainable hunting.&lt;/p&gt;