Range Of Prey Research Articles

Toxoplasma gondii Exposure and Dietary Habits of Two Sympatric Carnivores in the Valdivian Temperate Rainforest, Southern Chile.

Toxoplasma gondii, a parasitic protozoan, may infect most warm-blooded animals, including humans and carnivores. Our study focused on alien-invasive American minks (Neogale vison) and domestic cats (Felis catus) in the Valdivian Temperate Rainforest, Chile. The main goal was to investigate the relationship between their dietary habits and T. gondii exposure in the Valdivia River watershed. To detect T. gondii exposure, blood serum samples from 49 domestic cats and 40 American minks were analyzed using an ELISA, and stable isotope analysis of δ15N and δ13C from vibrissae was performed to determine the dietary habits of both species. Relationships between T. gondii exposure and dietary habits were explored using generalized linear mixed-effects models. American minks that were T. gondii seropositive exhibited a broader prey range compared to seropositive domestic cats, with minimal dietary overlap between the two groups. Exposure of domestic cats to T. gondii had no significant association with any isotope value or prey item in their diet. In American minks, we found a positive and significant association between the proportion of Domestic chicken (Gallus gallus domesticus) in the diet and high δ15N values with T. gondii exposure. This suggests that domestic species prey related to anthropogenic areas, and the consumption of high-trophic-level prey, may contribute to T. gondii exposure in American minks. Conversely, contrary to previous hypotheses, consumption of rodents showed no significant association with T. gondii exposure in either species. Our findings emphasize the importance of further research to investigate trophic interactions in the transmission dynamics of T. gondii in the Valdivian Temperate Rainforest.

Bdellovibrio bacteriovorus Therapy, an Emerging Alternative to Antibiotics

: The increase in multi-drug resistant (MDR) pathogens and the decline in the number of new antibiotics in the production pipeline pose a serious threat to our ability to treat infectious diseases. In this new landscape, once treatable diseases are now potentially life-threatening. This impending danger requires that urgent attention should be given to developing alternative strategies for combating MDR bacteria. A novel alternative is the use of predatory bacteria, B. bacteriovorus spp, that naturally prey on Gram-negative bacteria, including MDR Enterobacteriaceae. B. bacteriovorus has been shown to be nonpathogenic in animal models and on human cell lines, supporting its feasibility to be used to treat infections in animals and possibly humans. This document reviews various aspects of B. bacteriovorus biology, including its unique life cycle, "predatory toolbox", prey range, and recent research advances exploring B. bacteriovorus as an antimicrobial agent, stepping towards its use in human therapy. We also discuss the advantages and limitations of using B. bacteriovorus therapy and the strategies to overcome these limitations.

Predation of Natalus macrourus (Chiroptera: Natalidae) by Trachops cirrhosus (Chiroptera: Phyllostomidae) in a ferriferous Brazilian Amazon cave

Abstract Trachops cirrhosus bats are especially notable for feeding on various types of preys throughout its range, including other bat species. Here we report predation events of T. cirrhosus on Natalus macrourus, a new bat species among a wide range of prey.

The vampyrellid amoeba Strigomyxa ruptor gen. et sp. nov. and its remarkable strategy to acquire algal cell contents.

The vampire amoebae (Vampyrellida, Rhizaria) inhabit freshwater, marine, and terrestrial ecosystems and consume a wide range of eukaryotic prey. This includes diverse microalgae, fungi, and microscopic animals. One of the most captivating aspects of the vampyrellids is their ability to extract the cell contents of other eukaryotes after local dissolution of the prey cell wall, a feeding strategy that occurs in several vampyrellid families, but is best studied in Vampyrella species that attack zygnematophyte green algae. Here, we report two new vampyrellid strains from temperate moorlands in Germany with a yet-undescribed feeding strategy: internal protoplast extraction and cell wall regurgitation. This feeding strategy involves the phagocytosis of whole desmid cells (genus Closterium, Zygnematophyceae), internal cleavage of the algal cell wall, extraction of the cell contents, and subsequent exocytosis of bundled empty cell walls. The large primary food vacuole formed during the process has exceptional functions, as it forms internal feeding pseudopodia, packages algal cell contents into smaller secondary vacuoles, and transforms into a "waste vacuole" with cell wall remnants. The new feeding strategy, which - in the widest sense - is reminiscent of the pellet casting of owls, reveals a stunningly sophisticated behavior of single protist cells. Based on morphological, phylogenetic, and autecological data, both vampyrellid strains are nearly identical and here assigned to a new and quite unique vampyrellid taxon, Strigomyxa ruptor gen. et sp. nov. (Leptophryidae, Vampyrellida).

Biogeographical distribution and community assembly of Myxococcota in mangrove sediments

BackgroundMyxococcota, characterized by their distinct social lifestyles, are widely distributed micro-predators in global sediments. They can feed on a wide range of bacterial, archaeal, and fungal prey. Myxococcota are capable of producing diverse secondary metabolites, playing key roles in microbial food webs, and regulating the microbial community structures in different ecosystems. However, Myxococcota are rarely pure cultured due to the challenging and stringent culturing conditions. Their natural distribution, niche differentiation, and predator–prey relationships in a specific habitat are poorly understood.ResultsIn this study, we conducted a comprehensive analysis of the 16S rRNA gene sequence data from public databases and our collection. We compared the abundance, diversity, and distribution patterns of Myxococcota in various habitats, with a specific focus on mangroves. We found that Myxococcota accounted for 1.45% of the total prokaryotes in global sediments based on the abundance of 16S rRNA genes. Myxococcota are abundant and diverse in mangrove sediments. They tend to be more generalistic in mangroves than in other habitats due to their wide niche breadth. Besides, the deterministic processes (variable selection) influenced the assembly of mangrove Myxococcota communities significantly more than stochastic processes. Further, we determined that environmental factors explained a greater amount of total community variation in mangrove Myxococcota than geographical variables (latitude and sediment depth). In the end, through the analysis of microbial co-occurrence networks, Myxococcota emerges as a key component and functions as a connector in the mangrove microbial community.ConclusionsOur study enhances comprehension of mangrove Myxococcota's biogeography, assembly patterns, driving factors, and co-occurrence relationships, as well as highlights their unique niche and ecological importance in mangrove sediments.

HIGH FREQUENCY OF BATS IN THE DIET OF THE BARN OWL TYTO ALBA IN A LOWLAND DRY FOREST IN TOLIMA, COLOMBIA

The cosmopolitan distribution of the Barn Owl Tyto alba and its relatively well documented diet through the study of pellets have provided evidence of the broad diversity of prey it relies on. In most studies, both in tropical and temperate regions, rodents are its main prey, with other small mammals and vertebrates, and insects complementing its diet. Although bats have been recorded in the diet of T. alba at many localities, they seldom represent an important part of its diet. This study describes the diet of a small colony of T. alba from a mosaic of agricultural fields, pastures for cattle ranching and tropical dry forests in Tolima, central Colombia. Overall, we collected 516 pellets between 2016 and 2017 in a non-systematic manner, and recovered 335 skulls of rodents (67%), bats (29%), birds (3%) and shrews (1%), as well as invertebrate prey. The large proportion of bats in the diet of T. alba in this study is only matched by a few other studies, and further documents the wide range of prey included in the diet of this nocturnal raptor. This is one of the first studies on the diet of T. alba in tropical dry forests in Colombia and complements the existing data on its diet in the American tropics and worldwide.

Population dynamics and prey community of the invasive paper wasp Polistes chinensis (Hymenoptera: Vespidae) in a protected coastal habitat in New Zealand

AbstractThe Asian paper wasp (Polistes chinensis) is an invasive species in New Zealand and a voracious arthropod predator, incorporating a wide range of prey into its diet. We examined the colony survival and prey community composition of these wasps in a protected coastal habitat in New Zealand. Paper wasp colonies at this site were surveyed and monitored weekly over two summers. Our data showed that only ~20% of the monitored colonies each year survived until late summer, with high rates of colony mortality in late spring and early summer. We collected samples of wasp larval guts over a temporal gradient in one nesting season, and via DNA metabarcoding analysis, we identified the prey species consumed. The prey species most frequently identified in larval samples were endemic cicadas and several lepidopteran species. No native arthropod species of known conservation concern were identified in the analysis. However, 63% of the unique taxon sequences retrieved could not be identified by genus or species level, likely due to the absence of reference barcodes. These taxa may represent a group of understudied species, potentially highly endemic or localised. Our analysis indicates that these invasive wasps are opportunistic‐generalist predators with the potential to exert high predation pressure on native arthropods. P. chinensis may be preying on a range of understudied species, especially in remote, natural habitats across New Zealand. We recommend future studies continue to barcode native New Zealand arthropods in order to improve the taxonomic assignments of dietary studies.

Vertical trophic structure and niche partitioning of gelatinous predators in a pelagic food web: Insights from stable isotopes of siphonophores

AbstractGelatinous zooplankton are increasingly recognized as key components of pelagic ecosystems, and there have been many recent insights into their ecology and roles in food webs. To examine the trophic ecology of siphonophores (Cnidaria, Hydrozoa), we used bulk (carbon and nitrogen) and compound‐specific (nitrogen) isotope analysis of individual amino acids (CSIA‐AA). We collected samples of 15 siphonophore genera using blue‐water diving, midwater trawls, and remotely operated vehicles in the California Current Ecosystem, from 0 to 3000 m. We examined the basal resources supporting siphonophore nutrition by comparing their isotope values to those of contemporaneously collected sinking and suspended particles (0–500 m). Stable isotope values provided novel insights into siphonophore trophic ecology, indicating considerable niche overlap between calycophoran and physonect siphonophores. However, there were clear relationships between siphonophore trophic positions and phylogeny, and the highest siphonophore trophic positions were restricted to physonects. Bulk and source amino acid nitrogen isotope (δ15N) values of siphonophores and suspended particles all increased significantly with increasing collection depth. In contrast, siphonophore trophic positions did not increase with increasing collection depth. This suggests that microbially reworked, deep, suspended particles with higher δ15N values than surface particles, likely indirectly support deep‐pelagic siphonophores. Siphonophores feed upon a range of prey, from small crustaceans to fishes, and we show that their measured trophic positions reflect this trophic diversity, spanning 1.5 trophic levels (range 2.4–4.0). Further, we demonstrate that CSIA‐AA can elucidate the feeding ecology of gelatinous zooplankton and distinguish between nutritional resources across vertical habitats. These findings improve our understanding of the functional roles of gelatinous zooplankton and energy flow through pelagic food webs.

The barn owl as an accumulator of bone remains in central western Argentina: multi-taxa neo-taphonomic approach and implications for Holocene contexts

Barn owls are the most widely distributed group of owls in the world and are among the most common accumulators of small vertebrate remains at archeological and paleontological sites. Despite its importance as a bone remains accumulator and predictor of paleoenvironmental conditions due to its generalist habits, the vertebrate prey of this raptor has been scarcely studied from an ecological community perspective, especially considering the diverse range of prey it captures. Archeological, paleontological, and taphonomic studies typically reveal taxon-specific patterns, focusing primarily on small rodents. In order to overcome this problem, we studied an assemblage of vertebrate bones from barn owl pellets in the central Monte Desert of Argentina. Our analysis included the full range of prey taxa, including rodents, marsupials, birds, and reptiles, addressed from both an ecological and neo-taphonomic perspective. We compare the taxonomic and taphonomic findings with those from regional small vertebrate records obtained from various sampling types over the past 50 years to explore recent environmental changes within the Anthropocene. The assemblage of small vertebrate prey presented here comprises five species of cricetids, one species from the Caviidae family, and at least one ctenomyid rodent species. Additionally, the assemblage includes one species of didelphid marsupial, one reptile species, and at least six passeriform bird species that belong to separate families. The overall taphonomic trends are consistent with the typical barn owl pattern. However, our analysis identified a larger percentage of postcranial elements exhibiting signs of digestion compared to pellet-derived vertebrate bone assemblages previously documented. Furthermore, it is important to note that a significant proportion of avian bone fragments exhibit distinct signs of digestion.

Bdellovibrio svalbardensis sp. nov., a newly described predator isolated from Svalbard, Norway.

Identified as a newly described species from a biocrust in Svalbard, Norway (78° 54' 8.27″ N 12° 01' 20.34″ E), isolate PAP01T has different characteristics from any known predatory bacteria. The isolate was vibrio-shaped strain that employed flagellar motility. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the isolate clustered within the genus Bdellovibrio in the family Bdellovibrionaceae. 16S rRNA gene sequence similarities between strain PAP01T and the type strain (Bdellovibrio bacteriovorus HD100) was 95.7 %. The PAP01T genome has a size of 3.898 Mbp and possesses 3732 genes and a G+C content of 45.7 mol%. The results of genetic and physiological tests indicated the phenotypic differentiation of strain PAP01T from the two other Bdellovibrio species with validly published names. Based on the physiological and phylogenetic data, as well as the prey range spectrum and osmolality sensitivities, isolate PAP01T represents a novel species within the genus Bdellovibrio, for which the name Bdellovibrio svalbardensis sp. nov. is proposed. The type strain is PAP01T (=KCTC 92583T=DSM 115080T).

Biotic interactions vary across species' ranges and are likely conserved through geological time

AbstractAimThe evolutionary interactions between western spadefoot toads (genus Spea) represent a textbook example of character displacement, facilitated by dietary specialization of one Spea species on fairy shrimp (Anostraca) when all three co‐occur. The aim of this study is to understand the covariation between predator (Spea) and prey (Anostraca) range shifts in response to climate change oscillations, and whether biotic interactions can be used to project species distribution models on different time scales when studying species with dietary specialization. Taxon: Amphibia: Spea spp. and Crustacea: Anostraca.LocationNorth America.MethodsUsing multiple modelling techniques, we first estimated the potential distribution of central and western North American fairy shrimp species (Crustacea: Anostraca) and two western spadefoot toad species (Spea bombifrons and Spea multiplicata). We then created a shrimp species richness map by aggregating individual species estimates. Third, we studied the relationship between the probability of spadefoot toad presence and fairy shrimp species richness during the present and Last Glacial Maximum conditions. Finally, we estimated the strength and direction of the co‐occurrence between spadefoot toads and fairy shrimp sampled at the level of entire predicted range and at the regional level (allopatric and sympatric).ResultsFirst, the same abiotic environmental variables shape spadefoot toad and fairy shrimp species' distributions in central and western North America across time. Second, areas of sympatry of Spea bombifrons and Spea multiplicata correspond with dry conditions and higher shrimp richness. Finally, the spatial patterns of predator–prey co‐occurrence are highly variable across geography, forming a spatial mosaic over the species' ranges.Main ConclusionPredator–prey relationships form a spatial mosaic across geography and species ranges. Including biotic interactions into species distribution estimates for organisms with dietary specialization is highly recommended. Biotic interactions can be projected across different time frames for organisms with dietary specialization as they are likely conserved.

Sustained use of marine subsidies promotes niche expansion in a wild felid

The use of marine subsidies by terrestrial predators can facilitate substantial transfer of nutrients between marine and terrestrial ecosystems. Marine resource subsidies may have profound effects on predator ecology, influencing population and niche dynamics. Expanding niches of top consumers can impact ecosystem resilience and interspecific interactions, affecting predator-prey dynamics and competition. We investigate the occurrence, importance, and impact of marine resources on trophic ecology and niche dynamics in a highly generalist predator, the caracal (Caracal caracal), on the Cape Peninsula, South Africa. Caracals have flexible diets, feeding across a wide range of terrestrial and aquatic prey. We use carbon and nitrogen stable isotope analysis of fur samples (n = 75) to understand trophic position and niche shifts in coastal and inland foragers, as well as the implications of a diet rich in marine resources. We found significant differences in isotope signatures between these groups, with higher δ13C (P < 0.05) and δ15N values (P < 0.01) in coastal foragers. Isotope mixing models reveal that these elevated signatures were due to non-terrestrial food subsidies, where approximately a third of coastal foraging caracal diet comprised marine prey. The addition of marine prey species to diet increased both the trophic level and isotope niche size of coastal foraging caracals, with potential impacts on prey populations and competition. Our results suggest that marine prey are an important dietary resource for coastal foraging caracals, where seabirds, including two endangered species, are a major component of their diet. However, there are likely risks associated with these resource benefits, as routine consumption of seabirds is linked with higher pollutant burdens, particularly metals. Increased encounters between this terrestrial predator and seabirds may be a result of increased mainland colonies due to changes in habitat availability and the highly opportunistic and generalist foraging behaviour of a native predator.

The genetic basis of predation by myxobacteria.

Myxobacteria (phylum Myxococcota) are abundant and virtually ubiquitous microbial predators. Facultatively multicellular organisms, they are able to form multicellular fruiting bodies and swarm across surfaces, cooperatively hunting for prey. Myxobacterial communities are able to kill a wide range of prey microbes, assimilating their biomass to fuel population growth. Their mechanism of predation is exobiotic - hydrolytic enzymes and toxic metabolites are secreted into the extracellular environment, killing and digesting prey cells from without. However, recent observations of single-cell predation and contact-dependent prey killing challenge the dogma of myxobacterial predation being obligately cooperative. Regardless of their predatory mechanisms, myxobacteria have a broad prey range, which includes Gram-negative bacteria, Gram-positive bacteria and fungi. Pangenome analyses have shown that their extremely large genomes are mainly composed of accessory genes, which are not shared by all members of their species. It seems that the diversity of accessory genes in different strains provides the breadth of activity required to prey upon such a smorgasbord of microbes, and also explains the considerable strain-to-strain variation in predatory efficiency against specific prey. After providing a short introduction to general features of myxobacterial biology which are relevant to predation, this review brings together a rapidly growing body of work into the molecular mechanisms and genetic basis of predation, presenting a summary of current knowledge, highlighting trends in research and suggesting strategies by which we can potentially exploit myxobacterial predation in the future.

Evidence of diverse animal exploitation during the Middle Paleolithic at Ghar-e Boof (southern Zagros)

Although Middle Paleolithic (MP) hominin diets consisted mainly of ungulates, increasing evidence demonstrates that hominins at least occasionally consumed tortoises, birds, leporids, fish, and carnivores. Until now, the MP zooarchaeological record in the Zagros Mountains has been almost exclusively restricted to ungulates. The narrow range of hominin prey may reflect socioeconomic decisions and/or environmental constraints, but could also result from a research bias favoring the study of large prey, since archaeologists have undertaken no systematic taphonomic analyses of small game or carnivores in the region. Here, we report on the first comprehensive taphonomic analysis of an MP faunal assemblage from Ghar-e Boof (∼ 81–45 kyr), a Late Pleistocene site in the southern Zagros of Iran. Anthropogenic bone surface modifications point to hominins as the main agent of accumulation. Hominins preyed primarily on ungulates, particularly wild goat. However, we also found evidence for MP hominin exploitation of carnivores and tortoises at the site. Although small game represents only a minor portion of the diet, our results suggest that the hunting behavior of MP hominins in the Zagros was more diverse than previously thought, similar to what we find elsewhere in Eurasia.

Laboratory scale evaluation of the feasibility of locally found bladderworts as biological agents to control dengue vector, Aedes aegypti in Sri Lanka

BackgroundThe carnivorous genus Utricularia also includes aquatic species that have the potential to trap a wide range of prey, leading its death due to anoxia. However, the effectiveness of such an approach with carnivorous plants for vector control has not been evaluated in Sri Lanka.MethodsEarly instar (i & ii) and late instar (iii & iv) larvae of Aedes aegypti were exposed to locally found bladderwort (U. aurea Lour and Utricularia sp.). The experimental design was set with 10 larvae (both early and late instars separately) in 250 mL of water with bladderworts containing approximately 100 bladders in plant segments of both species, separately. Each treatment and control were repeated 50 times. The survival status of larvae was recorded daily until death or adult emergence. The larvae found whole or partially inside the bladders were attributed to direct predation. The Cox-regression model and Mantel-Cox log rank test were carried out to assess the survival probabilities of larvae in the presence of two bladderworts separately.ResultsThe highest predation was observed when using early instar larvae in both U. aurea (97.8%) and Utricularia sp. (83.8%). The mortality caused due to predation by U. aurea was observed to be significantly higher according to the Mantel-Cox log-rank test (HR = 60.71, CI; 5.69–999.25, P = 0.004). The mortality rates of late instar stages of Ae. aegypti were observed to be lower in both U. aurea (82.6%) and Utricularia sp. (74.8%). Overall, the highest predation efficacy was detected from U. aurea (HR = 45.02; CI: 5.96–850.51, P = 0.017) even in late instar stages. The results suggested the cumulative predation in both plants on Ae. aegypti larvae was > 72%.ConclusionsUtricularia aurea is a competent predator of Ae. aegypti larvae. Further, it is recommended to evaluate the feasibility of this plant to be used in the field as a control intervention in integrated vector management programmes.

Pseudovampyrella gen. nov.: A genus of Vampyrella-like protoplast extractors finds its place in the Leptophryidae.

Vampyrellid amoebae are predatory protists, which consume a variety of eukaryotic prey and inhabit freshwater, marine and terrestrial ecosystems. Although they have been known for almost 150 years, much of their diversity lacks an in-depth characterization. To date, environmental sequencing data hint at several uncharacterized lineages, to which no phenotype is associated. Furthermore, there are numerous historically described species without any molecular information. This study reports on two new vampyrellid strains from moorlands, which extract the protoplasts of Closterium species (Zygnematophyceae). Our data on morphology, prey range specificity and feeding strategy reveal that the studied vampyrellids are very similar to the historically described Vampyrella closterii. However, phylogenetic analyses demonstrate that the two strains do not belong to the genus Vampyrella and, instead, form a distinct clade in the family Leptophryidae. Hence, we introduce a new genus of algivorous protoplast extractors, Pseudovampyrella gen. nov., with the species P. closterii (= V. closterii) and P. minor. Our findings indicate that the genetic diversity of morphologically described vampyrellid species might be hugely underrated.

First Report of Pseudaspidimerus trinotatus (Thunberg) Feeding on Rhopalosiphum maidis (Fitch) Infesting Zea mays L.

Coccinellids are potential predators of various agricultural pests of economic significance and are widely exploited in biocontrol programmes. However among the described species of coccinellids, many of them remained unrecognized and researches were concentrated on a few coccinellids only. One such less exploited coccinellid, abundantly seen in many of the agricultural ecosystem is Pseudaspidimerus trinotatus (Thunberg). Earlier investigations on this beetle are limited. In this study, detailed illustrations and description notes were provided for P. trinotatus. Documentation of prey range of P. trinotatus was conducted. Rhopalosiphum maidis (Fitch) infesting Zea mays L. is reported as a new prey record for P. trinotatus. Further research on biological and ecological aspects of this beetle is needed to recognize its potential in regulating pest population in agro ecosystems.

Prey and habitat characteristics contribute to hotspots of distribution for an endangered coastal dolphin

IntroductionUnderstanding the characteristics of hotspots of species distribution provides opportunities for habitat-based management; a vital and often missing component in the conservation of mobile marine species. Correlates of species distribution derived from species distribution models (SDMs) are assumed to represent the characteristics of important habitat, which often include physical and biological (i.e., prey) components. In this study, we integrate surveys of Hector’s dolphin (Cephalorhynchus hectori) with in-situ data on environmental characteristics and prey to identify the statistical correlates of distribution and to assess ‘what makes hotspots unique’.MethodsBetween 2014 and 2017, ca. 300 surveys were carried out at hotspots and areas not routinely used by dolphins at Banks Peninsula on the east coast of New Zealand’s South Island. A broad range of prey and environmental variables were explored as drivers of dolphin distribution using generalized additive models, and principal component analysis was employed to determine a key environmental signature for hotspots.ResultsThe relative abundance of dolphins was strongly correlated with prey abundance and a range of environmental variables representing habitat type and oceanographic conditions. The combination of high prey abundance and sandy, shallow, high current and low turbidity habitat was strongly represented at hotspots.DiscussionThese characteristics are also likely attributes of habitat with high ecological value generally, being related to high biodiversity, productivity, naturalness and ecosystem function. This study showcases the importance of targeted investigations into the characteristics of species hotspots to better guide the management of important areas for the conservation of both species and ecosystems.

Transcriptomic response of Sinorhizobium meliloti to the predatory attack of Myxococcus xanthus.

Bacterial predation impacts microbial community structures, which can have both positive and negative effects on plant and animal health and on environmental sustainability. Myxococcus xanthus is an epibiotic soil predator with a broad range of prey, including Sinorhizobium meliloti, which establishes nitrogen-fixing symbiosis with legumes. During the M. xanthus-S. meliloti interaction, the predator must adapt its transcriptome to kill and lyse the target (predatosome), and the prey must orchestrate a transcriptional response (defensome) to protect itself against the biotic stress caused by the predatory attack. Here, we describe the transcriptional changes taking place in S. meliloti in response to myxobacterial predation. The results indicate that the predator induces massive changes in the prey transcriptome with up-regulation of protein synthesis and secretion, energy generation, and fatty acid (FA) synthesis, while down-regulating genes required for FA degradation and carbohydrate transport and metabolism. The reconstruction of up-regulated pathways suggests that S. meliloti modifies the cell envelop by increasing the production of different surface polysaccharides (SPSs) and membrane lipids. Besides the barrier role of SPSs, additional mechanisms involving the activity of efflux pumps and the peptide uptake transporter BacA, together with the production of H2O2 and formaldehyde have been unveiled. Also, the induction of the iron-uptake machinery in both predator and prey reflects a strong competition for this metal. With this research we complete the characterization of the complex transcriptional changes that occur during the M. xanthus-S. meliloti interaction, which can impact the establishment of beneficial symbiosis with legumes.

Body size predicts prey preference but not diet breadth in pythons

AbstractFor gape‐limited predators like snakes that swallow their prey whole, large‐bodied species with wide gapes should theoretically be able to consume a more diverse range of prey than smaller species with narrow gapes and, therefore, may have broader diets. However, in cases where large‐bodied species exclude small prey, their diets may not necessarily be more taxonomically diverse compared to smaller species. Thus, while body size can potentially predict broad dietary preferences, it cannot always predict diet breadth. We explored the relationship between body size and diet within the Pythonidae—a morphologically diverse clade of dwarf and giant snakes. We gathered ecological data of pythons and tested if python body lengths correlated with diet breadth and diet preferences respectively within a phylogenetic framework. Next, we reconstructed ancestral diets (as proportional use of ectothermic prey in their diets) and body lengths across a phylogeny of 36 species of pythons to explore the evolutionary relationship between these traits. We demonstrate that among extant pythons, body size is not linearly associated with diet breadth but linearly correlates with proportional use of ectothermic (and inversely endothermic) prey. Small‐bodied pythons more often have specialized diets dominated by the use of ectotherm prey whereas large‐bodied pythons tend to have diets dominated by the use of endotherm prey. We further show that the most recent common ancestor of pythons was likely large‐bodied and fed on a diet comprised mostly of endothermic prey. Shifts in diet towards greater proportional use of endothermic prey coincided with increases in body size. Conversely, shifts in diet towards greater proportional use of ectothermic prey coincided with decreases in body size. Our findings contribute to the growing body of work investigating the ecomorphological determinants of snake diets and thus provide further insight into our understanding of these animals' ecology and evolution.