Carnivorous Diet Research Articles

Ontogenetic development of intestinal length and relationships to diet in an Australasian fish family (Terapontidae).

BackgroundOne of the most widely accepted ecomorphological relationships in vertebrates is the negative correlation between intestinal length and proportion of animal prey in diet. While many fish groups exhibit this general pattern, other clades demonstrate minimal, and in some cases contrasting, associations between diet and intestinal length. Moreover, this relationship and its evolutionary derivation have received little attention from a phylogenetic perspective. This study documents the phylogenetic development of intestinal length variability, and resultant correlation with dietary habits, within a molecular phylogeny of 28 species of terapontid fishes. The Terapontidae (grunters), an ancestrally euryhaline-marine group, is the most trophically diverse of Australia’s freshwater fish families, with widespread shifts away from animal-prey-dominated diets occurring since their invasion of fresh waters.ResultsDescription of ontogenetic development of intestinal complexity of terapontid fishes, in combination with ancestral character state reconstruction, demonstrated that complex intestinal looping (convolution) has evolved independently on multiple occasions within the family. This modification of ontogenetic development drives much of the associated interspecific variability in intestinal length evident in terapontids. Phylogenetically informed comparative analyses (phylogenetic independent contrasts) showed that the interspecific differences in intestinal length resulting from these ontogenetic developmental mechanisms explained ~65% of the variability in the proportion of animal material in terapontid diets.ConclusionsThe ontogenetic development of intestinal complexity appears to represent an important functional innovation underlying the extensive trophic differentiation seen in Australia’s freshwater terapontids, specifically facilitating the pronounced shifts away from carnivorous (including invertebrates and vertebrates) diets evident across the family. The capacity to modify intestinal morphology and physiology may also be an important facilitator of trophic diversification during other phyletic radiations.

IS IT WRONG TO EAT ANIMALS?

AbstractEating meat appeals, but the cost is measured in millions of slaughtered animals. This has convinced many that vegetarianism is morally superior to a carnivorous diet. Increasingly, those who take pleasure in consuming animals find it a guilty pleasure. Are they correct? That depends on the magnitude of harm done to food animals but also on what sort of a good, if any, meat eating affords people. This essay aims to estimate both variables and concludes that standard arguments for moral vegetarianism are significantly misplaced. That is because the contribution of meat eating to lives of excellence is underestimated and overall harms to animals consequent on practices of meat eating are overestimated. The answer to the question posed in the title is, therefore, “No.”

The Gallbladder of the Electric Ray Torpedo Marmorata Risso Displays Excrescent Cholecystocytes with Merocrine and Apocrine‐Like Secretions

The gallbladder of Torpedo marmorata exhibits a mucosal surface layer of simple columnar epithelium with very tall cholecystocytes. The apical domain of each cell has few microvilli, but many mucous vesicles that are secreted by exocytosis at the cell apices. The apical regions may also elongate and undergo self-excision while shedding mucus and cell debris into the gallbladder lumen in a manner similar to that described in mammals as a result of sex steroid treatment to induce gallstones and to that found in the cholecystitis associated with cholelithiasis. Numerous small mitochondria, spherical to elongated, are distributed throughout the cells, while the nuclei are often located in the lower third of each cell. In the lower part of the cholecystocytes, large and very densely contrasted lysosomes can be found. All cells are tightly joined by junctional complexes, including long, highly contrasted desmosomes. The fibromuscular layer is made of a loose stroma with a limited muscular component and a poor blood supply. Large diameter blood vessels can only be found in the subserosal layer. It is hypothesized that the obligatorily carnivorous diet of this ureotelic fish has resulted in the evolution of a gallbladder ultrastructure resembling that found in cholecystitis but without the associated cholelithiasis.

Possible evidence of mammoth hunting at the Neanderthal site of Spy (Belgium)

Spy, a Belgian cave site famous for its Neanderthal remains, contains a wide spectrum of Pleistocene species. Horse, cave hyena, woolly mammoth, woolly rhinoceros and reindeer are the primary taxa. The Spy cave was used alternately by prehistoric humans and Pleistocene carnivores. This study considers whether prehistoric humans or carnivores are responsible for the large number of mammoth remains at the site. It is argued, on the basis of the frequency distribution of the skeletal elements of the mammoth, the age distribution of the mammoth molars, and the diet of the large carnivores and of the prehistoric humans, that the mammoth assemblage of Spy accumulated at the site through the activities of prehistoric humans. On the basis of AMS dates, the stratigraphic position of a number of mammoth molars and the absence of red ochre on the mammoth molars, it was concluded that these prehistoric humans were Neanderthals rather than Anatomically Modern Humans.

Gastro-Intestinal Complaints Related to Various Eating Behaviors

Background: Many studies report a beneficial health effect as well as a lower mortality rate for individuals following diets containing lots of fruits and vegetables. Results of studies on abdominal, and colon diseases are, however, inconsistent. Therefore, the aim of our study was to analyze differences between various eating behaviors and the incidence of gastro-intestinal complaints. Methods: The sample used for this study was taken from the Austrian Health Interview Survey ATHIS 2006/07 (N=14 318). Logistic regressions were calculated controlling for age, BMI, and physical activity to analyze differences regarding the incidence of gastric or intestinal ulcer, abdominal pain, and specific medication taken due to these complaints. Results: A lacto-/ovo-, as well as a semi-vegetarian diet is associated with a higher risk for gastrointestinal complaints. The odds ratio for gastric or intestinal ulcer, and the intake of specific medication is significantly higher for these diets. Conclusion: A carnivorous diet containing also lots of fruits and vegetables is recommended to avoid abdominal complaints. Furthermore, public health programs are needed in order to reduce the health risk due to nutritional factors.

A complete insect from the Late Devonian period

After terrestrialization, the diversification of arthropods and vertebrates is thought to have occurred in two distinct phases, the first between the Silurian and the Frasnian stages (Late Devonian period) (425-385 million years (Myr) ago), and the second characterized by the emergence of numerous new major taxa, during the Late Carboniferous period (after 345 Myr ago). These two diversification periods bracket the depauperate vertebrate Romer's gap (360-345 Myr ago) and arthropod gap (385-325 Myr ago), which could be due to preservational artefact. Although a recent molecular dating has given an age of 390 Myr for the Holometabola, the record of hexapods during the Early-Middle Devonian (411.5-391 Myr ago, Pragian to Givetian stages) is exceptionally sparse and based on fragmentary remains, which hinders the timing of this diversification. Indeed, although Devonian Archaeognatha are problematic, the Pragian of Scotland has given some Collembola and the incomplete insect Rhyniognatha, with its diagnostic dicondylic, metapterygotan mandibles. The oldest, definitively winged insects are from the Serpukhovian stage (latest Early Carboniferous period). Here we report the first complete Late Devonian insect, which was probably a terrestrial species. Its 'orthopteroid' mandibles are of an omnivorous type, clearly not modified for a solely carnivorous diet. This discovery narrows the 45-Myr gap in the fossil record of Hexapoda, and demonstrates further a first Devonian phase of diversification for the Hexapoda, as in vertebrates, and suggests that the Pterygota diversified before and during Romer's gap.

An Advanced Method to Assess the Diet of Free-Ranging Large Carnivores Based on Scats

BackgroundThe diet of free-ranging carnivores is an important part of their ecology. It is often determined from prey remains in scats. In many cases, scat analyses are the most efficient method but they require correction for potential biases. When the diet is expressed as proportions of consumed mass of each prey species, the consumed prey mass to excrete one scat needs to be determined and corrected for prey body mass because the proportion of digestible to indigestible matter increases with prey body mass. Prey body mass can be corrected for by conducting feeding experiments using prey of various body masses and fitting a regression between consumed prey mass to excrete one scat and prey body mass (correction factor 1). When the diet is expressed as proportions of consumed individuals of each prey species and includes prey animals not completely consumed, the actual mass of each prey consumed by the carnivore needs to be controlled for (correction factor 2). No previous study controlled for this second bias.Methodology/Principal FindingsHere we use an extended series of feeding experiments on a large carnivore, the cheetah (Acinonyx jubatus), to establish both correction factors. In contrast to previous studies which fitted a linear regression for correction factor 1, we fitted a biologically more meaningful exponential regression model where the consumed prey mass to excrete one scat reaches an asymptote at large prey sizes. Using our protocol, we also derive correction factor 1 and 2 for other carnivore species and apply them to published studies. We show that the new method increases the number and proportion of consumed individuals in the diet for large prey animals compared to the conventional method.Conclusion/SignificanceOur results have important implications for the interpretation of scat-based studies in feeding ecology and the resolution of human-wildlife conflicts for the conservation of large carnivores.

Scientific Opinion on the safety and efficacy of taurine as a feed additive for all animal species

Taurine is a beta-amino acid, not incorporated into proteins. Taurine is involved in a number of physiological processes. In cats, dietary taurine at requirement/allowance levels is safe with a margin of safety of between 4 and 20. The few data available for carnivorous fish indicate that levels between 2.0 % and 2.5 % are safe. It is further concluded that up to 0.2 % taurine in feed is tolerated by all animal species. The FEEDAP Panel estimates the observed safe level in humans to be 6 g/person per day (corresponding to 100 mg/kg body weight per day). Exposure resulting from the consumption of foodstuffs and ‘energy drinks’ together would amount to about one-third of the observed safe level. Population oral exposure data include taurine from foodstuffs of animal origin, such as animal tissue and products, resulting from feed supplementation. However, exposure resulting from this source is estimated to be low since, to the knowledge of the FEEDAP Panel, the use of taurine as a feed additive is mainly restricted to cats and dogs. The use of taurine as a feed additive for all animal species would not raise concerns about consumer safety. In the absence of data, taurine is considered to be a skin and eye irritant and skin sensitiser, and to be hazardous if inhaled. A risk to the environment resulting from the use of taurine in animal nutrition is not foreseen. Synthetic taurine is considered efficacious for use in cat, dog and carnivorous fish diets. In the case of poultry, pigs and ruminants, no studies demonstrating beneficial effects of taurine supplementation on performance, health or product quality have been found. In laying hens, dietary supplementation with 0.25-0.5 % taurine has been shown to have an adverse effect (reduced egg weight).

Normal Plasma Cholinesterase Activity of Neotropical Falconiformes and Strigiformes

Abstract Raptors are highly susceptible to poisoning by anticholinesterase drugs and pesticides, such as organophosphates and carbamates, due to their carnivorous and/or insectivorous diets. Measurement of plasma cholinesterase inhibition is a proxy indicator of exposure to these agents; however, prior knowledge of the normal plasma cholinesterase activity of healthy birds is required for interpretation of results. Such normal values have not yet been established for most species of neotropical raptors. We collected blood samples from 133 raptors, including eleven species of Falconiformes (n = 45) and seven species of Strigiformes (n = 88). The birds had no clinical signs or history of possible exposure to anticholinesterase drugs and were housed in rehabilitation centers (free-ranging animals) and zoos (captive animals) in the state of Sao Paulo, southeastern Brazil. We found that plasma cholinesterase activity, as measured by the Ellman method, had a logarithmic distribution with a median of 0.58 µm...

Developmental reversal in neuropeptide Y action on feeding in an amphibian

Neuropeptide Y (NPY) is expressed in the hypothalamus where it exerts orexigenic actions within the feeding control circuit. While NPY stimulates feeding in juvenile and adult animals, it is not known whether NPY influences food intake at earlier life stages. We investigated a role for NPY in regulating feeding at two stages of the life cycle of an amphibian, the Western spadefoot toad Spea hammondii. We administered NPY by intracerebroventricular (i.c.v.) injection to juvenile toads or prometamorphic tadpoles, and monitored locomotion, feeding behavior and/or food intake. Injection of NPY (20 or 200ng/g BW) into juvenile toads decreased the latency to, and increased the number of strikes at prey, and the number of crickets eaten compared to uninjected or vehicle-injected controls. By contrast, injection of NPY (0.02–20ng/g BW) into prometamorphic tadpoles caused a dose-dependent decrease in time spent foraging compared to controls. Blocking NPY signaling in the prometamorphic tadpole brain by i.c.v. injection of a general NPY receptor antagonist increased foraging, and partly blocked the action of exogenous NPY on foraging. Taken together, our findings show a developmental reversal in NPY actions on feeding in an amphibian, with the peptide having a characteristic orexigenic action in the juvenile toad, but an inhibitory action on foraging in the prometamorphic tadpole. The anorexigenic action of NPY in the tadpole correlates with a decrease in feeding that occurs at metamorphic climax when the tadpole’s gut and cranium remodels for the transition to a carnivorous diet.

EXAMINATION OF EFFECT OF DIET, PH, AND AGE ON CHITINASE ACTIVITY IN THE GUT OF THE YELLOW‐BELLIES SLIDER TURTLE TRACHEMYS SCRIPTA

The Slider Turtle, Trachemys scripta, undergoes an ontogenetic dietary shift during its life. During this shift, juvenile turtles prefer to eat aquatic invertebrates, which contain chitin in their exoskeletons. Digestive enzymes, like chitinase, are needed to help break down the exoskeleton allowing access to the underlying nutrients. A fluorescent chitinase assay for exochitinase was adapted for these studies. Enzymatic activity was detected in extracts of stomach, small intestine, large intestine, and pancreas obtained from five year old T. scripta fed a mixed diet. This work aimed to establish the existence and location of an endogenous chitinase and identify its optimal pH ranges in T. scripta hatchlings. Hatchlings typically have a more carnivorous diet which may result in an increase of chitinase within their gut. The procedure used on the five year old turtles is being repeated on hatchling turtles to determine if activity levels vary with age. This work was sponsored by the Merck AAAS Undergraduate Science Research Program.

Coprolites as a source of information on the genome and diet of the cave hyena

We performed high-throughput sequencing of DNA from fossilized faeces to evaluate this material as a source of information on the genome and diet of Pleistocene carnivores. We analysed coprolites derived from the extinct cave hyena (Crocuta crocuta spelaea), and sequenced 90 million DNA fragments from two specimens. The DNA reads enabled a reconstruction of the cave hyena mitochondrial genome with up to a 158-fold coverage. This genome, and those sequenced from extant spotted (Crocuta crocuta) and striped (Hyaena hyaena) hyena specimens, allows for the establishment of a robust phylogeny that supports a close relationship between the cave and the spotted hyena. We also demonstrate that high-throughput sequencing yields data for cave hyena multi-copy and single-copy nuclear genes, and that about 50 per cent of the coprolite DNA can be ascribed to this species. Analysing the data for additional species to indicate the cave hyena diet, we retrieved abundant sequences for the red deer (Cervus elaphus), and characterized its mitochondrial genome with up to a 3.8-fold coverage. In conclusion, we have demonstrated the presence of abundant ancient DNA in the coprolites surveyed. Shotgun sequencing of this material yielded a wealth of DNA sequences for a Pleistocene carnivore and allowed unbiased identification of diet.

Prey preference of snow leopard (Panthera uncia) in South Gobi, Mongolia.

Accurate information about the diet of large carnivores that are elusive and inhabit inaccessible terrain, is required to properly design conservation strategies. Predation on livestock and retaliatory killing of predators have become serious issues throughout the range of the snow leopard. Several feeding ecology studies of snow leopards have been conducted using classical approaches. These techniques have inherent limitations in their ability to properly identify both snow leopard feces and prey taxa. To examine the frequency of livestock prey and nearly-threatened argali in the diet of the snow leopard, we employed the recently developed DNA-based diet approach to study a snow leopard population located in the Tost Mountains, South Gobi, Mongolia. After DNA was extracted from the feces, a region of ∼100 bp long from mitochondrial 12S rRNA gene was amplified, making use of universal primers for vertebrates and a blocking oligonucleotide specific to snow leopard DNA. The amplicons were then sequenced using a next-generation sequencing platform. We observed a total of five different prey items from 81 fecal samples. Siberian ibex predominated the diet (in 70.4% of the feces), followed by domestic goat (17.3%) and argali sheep (8.6%). The major part of the diet was comprised of large ungulates (in 98.8% of the feces) including wild ungulates (79%) and domestic livestock (19.7%). The findings of the present study will help to understand the feeding ecology of the snow leopard, as well as to address the conservation and management issues pertaining to this wild cat.

Differences in diet and trophic interactions of Patagonian carnivores between areas with mostly native or exotic prey

The prey base for Patagonian carnivores has been altered greatly over the past 150 years due to widespread overgrazing by livestock, invasions by exotic wildlife, and hunting. On ranches in northern Patagonia carnivores consume mostly exotic species, and native herbivores are ecologically extinct in their role as prey. In this study we compare diets of the culpeo (Lycalopex culpaeus), chilla (L. griseus), puma (Puma concolor), Geoffroy's cat (Leopardus geoffroyi), colocolo (L. colocolo), and hog-nosed skunks (Conepatus chinga and C. humboldtii) in a reserve with a mostly native prey base to their diets on the ranches, and evaluate how differences in prey bases affect trophic interactions among carnivores. Carnivores in the reserve consumed mostly native prey. Dietary overlap among carnivores was not significant on the reserve, but was highly significant on the ranches. This homogenization of diets where densities of native species are reduced could lead to stronger negative interactions among carnivores, altering the composition of the carnivore assemblage to the detriment of the more specialized species. Study of carnivore diets may be a relatively quick way to evaluate the conservation status and ecological functionality of prey assemblages in Patagonia and other areas where these have been altered.

Paleoecology of late Pleistocene–Holocene faunas of eastern and central Wyoming, USA, with implications for LGM climate models

Oxygen and carbon isotope compositions of teeth were measured for a variety of fossil herbivores, omnivores and carnivores from Natural Trap Cave (NTC) and Little Box Elder Cave (LBEC), central eastern Wyoming, USA. These sites host some of the best preserved and most abundant late Pleistocene to early Holocene mammal fossils, and provide key information about ecological and climatic change attending the Pleistocene–Holocene transition. Average Pleistocene compositions are consistent with C3-dominated diets, but C4 grass consumption increased in Bison from the late Pleistocene to today. A single Sangamonian Equus tooth also has elevated 13C, suggesting that C4 biomass increased during interglacials in general. Tooth δ18O values imply local water δ18O values at NTC of −15 to −16‰ during the Last Glacial Maximum (LGM) and −14‰ today, consistent with modern regional studies and general circulation models (GCM's) for the LGM. Water δ18O values at LBEC were ~−12‰. Although herbivore compositions are consistent with theoretical expectations, carnivores exhibit lower δ13C and higher δ18O values relative to herbivores than anticipated. These discrepancies could reflect poorly understood carnivore physiologies or diets, and emphasize the need for further investigation of isotope systematics in carnivores. Isotope zoning in several herbivore teeth shows negative correlations between carbon and oxygen isotopes: high and low δ18O values representing summer and winter seasons occur with low and high δ13C values respectively. This trend could indicate seasonally changing diets, e.g. consumption of drier foods or conifers during the winter, or burning of stored fat during the winter. Increasing δ18O values from the Pleistocene to Holocene in water-dependent taxa are consistent with an increasing proportion of summer moisture derived from the Gulf of Mexico, as predicted by isotope-enabled GCM's. Mean annual precipitation during the late Pleistocene is estimated at ≤350mm/yr, similar to modern day (c. 200mm/yr), indicating that dry conditions have prevailed for the last 25ka in Wyoming. A revised analytical expression for C4 plant abundance in the western US is proposed that accounts for climate variables and pCO2. Combination of this expression with the climate predictions of the PMIP2 ensemble average GCM explains LGM C4 plant abundances at NTC, southern Texas, and Florida. Changes to C4 plant abundances may provide sensitive tests of GCM accuracies.

Fermentation of animal components in strict carnivores: A comparative study with cheetah fecal inoculum1,2

The natural diet of felids contains highly digestible animal tissues but also fractions resistant to small intestinal digestion, which enter the large intestine where they may be fermented by the resident microbial population. Little information exists on the microbial degradability of animal tissues in the large intestine of felids consuming a natural diet. This study aimed to rank animal substrates in their microbial degradability by means of an in vitro study using captive cheetahs fed a strict carnivorous diet as fecal donors. Fresh cheetah fecal samples were collected, pooled, and incubated with various raw animal substrates (chicken cartilage, collagen, glucosamine-chondroitin, glucosamine, rabbit bone, rabbit hair, and rabbit skin; 4 replicates per substrate) for cumulative gas production measurement in a batch culture technique. Negative (cellulose) and positive (casein and fructo-oligosaccharides; FOS) controls were incorporated in the study. Additionally, after 72 h of incubation, short-chain fatty acids (SCFA), including branched-chain fatty acids (BCFA), and ammonia concentrations were determined for each substrate. Glucosamine and glucosamine-chondroitin yielded the greatest organic matter cumulative gas volume (OMCV) among animal substrates (P < 0.05), whereas total SCFA production was greatest for collagen (P < 0.05). Collagen induced an acetate production comparable with FOS and a markedly high acetate-to-propionate ratio (8.41:1) compared with all other substrates (1.67:1 to 2.97:1). Chicken cartilage was rapidly fermentable, indicated by a greater maximal rate of gas production (R(max)) compared with all other substrates (P < 0.05). In general, animal substrates showed an earlier occurrence for maximal gas production rate compared with FOS. Rabbit hair, skin, and bone were poorly fermentable substrates, indicated by the least amount of OMCV and total SCFA among animal substrates (P < 0.05). The greatest amount of ammonia production among animal substrates was measured after incubation of collagen and rabbit bone (P < 0.05). This study provides the first insight into the potential of animal tissues to influence large intestinal fermentation in a strict carnivore, and indicates that animal tissues have potentially similar functions as soluble or insoluble plant fibers in vitro. Further research is warranted to assess the impact of fermentation of each type of animal tissue on gastro-intestinal function and health in the cheetah and other felid species.

Carnivore diet analysis based on next‐generation sequencing: application to the leopard cat (Prionailurus bengalensis) in Pakistan

Diet analysis is a prerequisite to fully understand the biology of a species and the functioning of ecosystems. For carnivores, traditional diet analyses mostly rely upon the morphological identification of undigested remains in the faeces. Here, we developed a methodology for carnivore diet analyses based on the next-generation sequencing. We applied this approach to the analysis of the vertebrate component of leopard cat diet in two ecologically distinct regions in northern Pakistan. Despite being a relatively common species with a wide distribution in Asia, little is known about this elusive predator. We analysed a total of 38 leopard cat faeces. After a classical DNA extraction, the DNA extracts were amplified using primers for vertebrates targeting about 100 bp of the mitochondrial 12S rRNA gene, with and without a blocking oligonucleotide specific to the predator sequence. The amplification products were then sequenced on a next-generation sequencer. We identified a total of 18 prey taxa, including eight mammals, eight birds, one amphibian and one fish. In general, our results confirmed that the leopard cat has a very eclectic diet and feeds mainly on rodents and particularly on the Muridae family. The DNA-based approach we propose here represents a valuable complement to current conventional methods. It can be applied to other carnivore species with only a slight adjustment relating to the design of the blocking oligonucleotide. It is robust and simple to implement and allows the possibility of very large-scale analyses.

A quantitative approach to the cranial ontogeny of Lycalopex culpaeus (Carnivora: Canidae)

The study of cranial ontogeny is important for understanding the relationship between form and function in developmental, ecological, and evolutionary contexts. The transition from lactation to the diet of adult carnivores must be accompanied by pronounced modifications in skull morphology and feeding behavior. Our goal was to study relative growth and development in the skull ontogeny of the canid Lycalopex culpaeus, and interpret our findings in a functional context, thereby exploring the relationship between changes in shape and size with dietary habits and age stages. We performed quantitative analyses, including multivariate allometry and geometric morphometrics. Our results indicate that shape changes are related to functional improvements of the jaw mechanics related for food catching/processing. Estimates of full muscle size, mechanical advantage, and adult cranial shape are reached after sexual maturity, while adult mandible and skull size are reached after weaning, which is related to diet change (incorporation of meat and other food items). The ontogenetic pattern observed in L. culpaeus is similar to those observed in Canis familiaris and C. latrans. However, the magnitude of change seen in L. culpaeus is smaller than those seen in the felid Puma concolor and considerably smaller than those seen in the bone cracker hyaenid Crocuta crocuta. These patterns are associated with dietary habits and specializations in skull anatomy, as L. culpaeus, domestic dog and coyote are generalist species compared with hypercarnivores such as C. crocuta and P. concolor.

Diet mediates the relationship between longevity and reproduction in mammals

The disposable soma hypothesis posits a negative correlation between longevity and reproduction, presumably because these aspects of fitness compete for a limited pool of nutrients. However, diet, which varies widely among animals, could affect the availability of key nutrients required for both reproduction and longevity, especially protein. We used a comparative database of mammal life history data to test the hypothesis that carnivores experience less of a negative relationship between reproduction and longevity than herbivores. Annual reproduction and adult mass were significant predictors of longevity among all mammals; although, the relative importance of reproduction and mass for explaining longevity varied among trophic levels. In herbivores, reproduction was a stronger predictor of longevity than mass. Carnivores showed the opposite pattern with reproduction explaining much less of the variation in longevity. Omnivores showed an intermediate pattern with mass and reproduction explaining similar amounts of variation in longevity. In addition, longevity and reproduction were significantly higher in omnivores than herbivores and carnivores, which were not different from each other. Higher dietary protein at higher trophic levels may allow mammals to avoid potential conflicts between reproduction and longevity. However, there may be potential costs of carnivorous diets that limit the overall performance of carnivores and explain the peak in reproduction and longevity for omnivores.

Intraspecific predation in the Liolaemus lizard radiation: a primer

Intraspecific predation (cannibalism) occurs in a number of lizard species, although the incidence of this trophic behaviour appears to be infrequent. Within the South AmericanLiolaemuslizard evolutionary radiation, the primary component of the carnivorous diet (herbivory has also evolved in several species) includes a diversity of arthropods and other invertebrates. However, a number of cases of saurophagy, mostly cannibalism, have also been reported in different species. Here, I review for the first time the occurrence of cannibalism in this prominent group of lizards, one of the largest and more ecologically diverse living adaptive radiations. Adults of fiveLiolaemusspecies have previously been reported to feed on conspecific hatchlings, and one additional case (L. zapallarensis) is reported in this paper. In general, cannibalism is found in species located at the right side of the body size frequency distribution, while no cases have been reported on the far left range of body sizes, suggesting that cannibalism is more common in large species. Only one species of medium size (L. darwinii) is known to feed on conspecifics. In addition, males are responsible for 83% of the cases of cannibalism, while only one case of female cannibalism is known (L. chiliensis). Finally, no clear phylogenetic signal can be inferred from these observations, as the six reported cannibal species belong to four of the five mainLiolaemusclades.