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opencc-zeroOct 2020View details →

Raw data used in: Variations in effects of ectosymbiotic microbes on the growth rates among different species and genotypes of Daphnia fed different algal diets

Several recent studies have shown that ectosymbiotic bacterial microbiota, including gut microbes, affect the growth and reproduction of Daphnia, a key organism in lake ecosystems. However, these studies examined specific species, such as the model organism, D. magna, and used green algae as food. It is unclear if symbiotic bacteria affect fitness in other Daphnia species common in lakes and ponds in Japan. In this study, we examined the growth rates of sterilized individuals of two D. pulex genotypes with D. magna using the green algae Scenedesmus and the diatom Cyclotella as algal diets. In addition, we examined the growth rate of the sterilized Daphnia pulex individuals infected by Limnohabitans spp., previously reported to promote the fitness of D. magna as ectosymbiotic bacteria. We found that the effects of ectosymbiotic bacteria on growth rate differed not only between different genotypes of D. pulex but also between individuals fed the different algal diets. The results suggest that the genotype- and diet-specific differences in fitness-dependency on the ectosymbiotic microbiota can be factors affecting the genetic structures of D. pulex populations.

opencc-zeroJan 2021View details →

Diet variation driven by color vision phenotype in wild capuchin monkeys

The polymorphic color vision of platyrrhine monkeys is a fascinating example of balancing selection acting on multiple genetic and phenotypic morphs. Yet, the mechanism of natural selection maintaining this variation remains elusive. Past research has demonstrated task-specific foraging advantages to dichromatic (two-opsin vision, red-green colorblind) and trichromatic (three-opsin vision, human "normal") monkeys, raising the potential for dietary niche differentiation. We ask whether color vision type influences diet variation in a population of wild, white-faced capuchins (Cebus imitator) in Costa Rica. To assess this, we record food intake during simultaneous focal follows of adult female dichromats and trichromats, and classify the conspicuity of diet items in capuchin visual space. We assess the degree of dietary and nutritional niche overlap during periods of high and low fruit abundance using nutritional geometry and Pianka's index. We find that in months of high fruit abundance, trichromats have higher intake of conspicuously-colored fruits, while dichromats have higher intake of camouflaged invertebrates, resulting in lower niche overlap. These differences disappear in months of low habitat-wide fruit abundance, a time when overall dietary breadth collapses. Our results support the hypothesis that niche differentiation in diet contributes to maintaining color vision variation without compromising species-specific nutritional intake.

opencc-zeroMay 2020View details →

Spatial variation in diet-microbe associations across populations of a generalist North American carnivore

1. Generalist species, by definition, exhibit variation in niche attributes that promote survival in changing environments. Increasingly, phenotypes previously associated with a species, particularly those with wide or expanding ranges, are dissolving and compelling greater emphasis on population-level characteristics. 2. In the present study, we assessed spatial variation in diet characteristics, gut microbiome, and the association between these two ecological traits across populations of coyotes (Canis latrans). We highlight the influence of the carnivore community in shaping these relationships, as the coyote varied from being an apex predator to a subordinate, mesopredator across sampled populations. 3. We implemented a scat survey across three distinct coyote populations in Michigan, USA. We used carbon (δ13C) and nitrogen (δ15N) isotopic values to reflect consumption patterns and trophic level, respectively. Corresponding samples were also paired with 16S rRNA sequencing to describe the microbial community and correlate with isotopic values. 4. Though consumption patterns were comparable, we found spatial variation in trophic level among coyote populations. Specifically, δ15N was highest where coyotes were the apex predator and lowest where coyotes co-occurred with gray wolves (Canis lupus). 5. The gut microbial community exhibited marked spatial variation across populations with the lowest OTU diversity found where coyotes occurred at their lowest trophic level. Bacteriodes and Fusobacterium dominated the microbiome and were positively correlated across all populations. We found no correlation between δ13C and microbial community attributes. However, positive associations between δ15N and specific microbial genera increased as coyotes ascended trophic levels. 6. Coyotes provide a model for exploring implications of niche plasticity because they are a highly adaptable, wide-ranging omnivore. As coyotes continue to vary in trophic position and expand their geographic range, we might expect increased divergence within their microbial community, changes in physiology, and alterations in behavior. 05-May-2020

opencc-zeroDec 2017View details →

Data from: A combined mesowear analysis of Mexican Bison antiquus shows a generalist diet with geographical variation

Bison antiquus was one of the largest and most widely distributed megafaunal species during the Late Pleistocene in North America, giving rise to the modern plains bison in the middle Holocene. Despite the importance of the ancient bison, little is known about its feeding ecology. We employed a combination of extended mesowear, and mesowear III to infer the diet preference and habitat use of three Mexican samples of B. antiquus. Two northern samples from the Transmexican Volcanic Belt morphotectonic Province: La Piedad-Santa Ana and La Cinta-Portalitos, as well as one southern sample from the Sierra Madre del Sur morphotectonic province: Viko Vijin. We found that the northern Mexican samples were primarily non-strict grazers, while the southern sample displays a pattern consistent with mixer feeder habits. This suggests variability among the diets of these bison samples, caused by different paleoenvironments. This evidence complements the paleoenvironmental reconstructions in the studied localities; for the northern samples, open prairies composed of patches of woodland or shrubland and for the southern locality a fluvial floodplain with short-lived vegetation. In both scenarios, grasses (Poaceae) were non-dominant. The dietary habits of our samples of ancient bison in Mexico are the southernmost dietary inference for the species in North America and expand our knowledge of the dietary habits of Bison antiquus during the late Pleistocene.

opencc-zeroDec 2015View details →

Data from: Latitudinal variation in ecological opportunity and intraspecific competition indicates differences in niche variability and diet specialization of Arctic marine predators

Individual specialization (IS), where individuals within populations irrespective of age, sex, and body size are either specialized or generalized in terms of resource use, has implications on ecological niches and food web structure. Niche size and degree of IS of near-top trophic-level marine predators have been little studied in polar regions or with latitude. We quantified the large-scale latitudinal variation of population- and individual-level niche size and IS in ringed seals (Pusa hispida) and beluga whales (Delphinapterus leucas) using stable carbon and nitrogen isotope analysis on 379 paired ringed seal liver and muscle samples and 124 paired beluga skin and muscle samples from eight locations ranging from the low to high Arctic. We characterized both within- and between-individual variation in predator niche size at each location as well as accounting for spatial differences in the isotopic ranges of potential prey. Total isotopic niche width (TINW) for populations of ringed seals and beluga decreased with increasing latitude. Higher TINW values were associated with greater ecological opportunity (i.e., prey diversity) in the prey fish community which mainly consists of Capelin (Mallotus villosus) and Sand lance (Ammodytes sp.) at lower latitudes and Arctic cod (Boreogadus saida) at high latitudes. In beluga, their dietary consistency between tissues also known as the within-individual component (WIC) increased in a near 1:1 ratio with TINW (slope = 0.84), suggesting dietary generalization, whereas the slope (0.18) of WIC relative to TINW in ringed seals indicated a high degree of individual specialization in ringed seal populations with higher TINWs. Our findings highlight the differences in TINW and level of IS for ringed seals and beluga relative to latitude as a likely response to large-scale spatial variation in ecological opportunity, suggesting species-specific variation in dietary plasticity to spatial differences in prey resources and environmental conditions in a rapidly changing ecosystem.

opencc-zeroDec 2016View details →

Data from: High interannual variation in the diet of a tropical forest frugivore (Hylobates lar)

Frugivores must deal with seasonal changes in fruit availability and changes from year to year, as most species of tropical forest fruiting trees have considerable interannual variation in phenology and many are mast fruiters. We quantified seasonal and interannual changes in the fruit diet in a frugivore and important seed disperser, the white-handed gibbon, Hylobates lar, in Thailand. We used 40-day following data during April and May replicated in six consecutive years to study interannual variability in the diet, and compared it with seasonal changes measured in monthly samples of the same size collected in three successive years. The 40-day periods of following also allowed us to measure the decline in dietary similarity with time over a finer scale. We measured fruit diet similarity between replicated 5-day periods using the percentage overlap (Renkonen's) index, and Jaccard's similarity index. Seasonally, average dietary overlap between adjacent months was low, and similarity approached zero after four months. Average rate of decline in similarity exceeded 20 percent per five day period. Variation in fruit species in the diet between years was high, and was correlated with interannual variation in fruiting phenology. The strongest correlation occurred in the case of Nephelium melliferum, a highly preferred species that dominated the diet in good fruiting years. It is difficult to separate changes in food-species preference from changes in availability from year to year. We devised a relative measure of preference that depends on the degree to which the gibbons rely on prior knowledge to find sources.

opencc-zeroMar 2022View details →

Data from: Prairie dogs, cattle subsidies, and alternative prey: Seasonal and spatial variation in coyote diet in a temperate grassland

As the dominant predator on North America's grasslands, coyotes (Canis latrans) have a large influence on biodiversity, both on working ranches and in protected parks. Ground squirrel (sciurid) species and livestock carrion are often abundant on grasslands worldwide and have the potential to influence a predator's consumption of alternative prey. We collected 1321 scats in four seasons over two years in and adjacent to Grasslands National Park, Saskatchewan, to test the hypothesis that seasonal and spatial variation in consumption of sciurid prey and cattle (Bos taurus) carrion influenced coyote consumption of alternative prey. Sciurid (black-tailed prairie dog Cynomys ludovicianus and Richardson's ground squirrel Urocitellus richardsonii) remains were common from spring to fall and had a strong inverse relationship with deer (mule deer Odocoileus hemionus and white-tailed deer O. virginianus), which were most common in winter scats. Cattle remains were most common during spring, fall and winter, occurring in 10.6% of scats annually. Biomass estimates indicated that cattle was the highest ranked food on cattle grazing land year-round, and the 2nd ranked food, after deer, during winter on the portion of the park from which cattle were excluded. Closer proximity of scats to a prairie dog colony increased the likelihood of prairie dog remains throughout the year and reduced the likelihood of cattle remains in scats from spring to fall, but not during winter. Individual differences in foraging and ranging behavior may explain the spatial distribution of prairie dog versus cattle in scats. Further work is needed to determine whether sciurid prey, deer, or livestock carrion support large predator populations on grassland habitats to a level that may negatively affect coexisting prey species, including species at risk.

FIGURE 7 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 7. Lateral fields (A-C) and tail shape variations (D-I). A. Four lateral lines in Ditylenchus dipsaci; B. Six lateral lines in D. myceliophagus; C. Additional lines between main lines in D. destructor; D. Pointed tail terminus in male of D. destructor; E. Thick tail with rounded terminus in D. myceliophagus; F. Thin tail with pointed terminus in D. medicaginis; G & H. Finely rounded tail terminus in D. geraerti and D. destructor; I. Mucronate tail terminus in D. parvus. All scale-bars = 10 µm.

FIGURE 6 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 6. Effect of different temperature treatments on means of morphometric indices of pure population of Ditylenchus myceliophagus. Bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

FIGURE 5 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 5. Effect of different temperature treatments on means of morphometric indices of pure populations of Ditylenchus dipsaci (Garlic and alfalfa populations). In each population, bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

FIGURE 3 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 3. Effect of different diet treatments on means of morphometric indices of pure population of Ditylenchus myceliophagus. Bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

FIGURE 4 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 4. Effect of different temperature treatments on means of morphometric indices of pure populations of Ditylenchus destructor (Hamadan, Kerman and Fars populations; codes 188, 347 and 348, respectively). In each population, bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

FIGURE 2 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 2. Effect of different diet treatments on means of morphometric indices of pure populations of Ditylenchus dipsaci (Garlic and alfalfa populations). In each population, bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

FIGURE 1 in Intraspecific variations of morphometric indices of some species of the genus Ditylenchus Filipjev, 1936 (Nematoda: Anguinidae) in relation to diet and temperature

FIGURE 1. Effect of different diet treatments on means of morphometric indices of pure population of Ditylenchus destructor (Hamadan population, code 188). Bars with the same letter(s) are not significantly different (P <0.05), according to Duncan's Multiple Range Test.

opencc-zeroMay 2022View details →

Data from: Variation in red fox Vulpes vulpes diet in five continents

Understanding variation in the diet of widely distributed species can help us to predict how they respond to future environmental and anthropogenic changes. We studied the diet of the red fox Vulpes vulpes, one of the world's most widely distributed carnivores. We compiled dietary data from 217 studies at 276 locations in five continents to assess how fox diet composition varied according to geographic location, climate, anthropogenic impact and sampling method. The diet of foxes showed substantial variation throughout the species' range, but with a general trend for small mammals and invertebrates to be the most frequently occurring dietary items. The incidence of small and large mammals and birds in fox diets was greater away from the equator. The incidence of invertebrates and fruits increased with mean elevation, while the occurrence of medium-sized mammals and birds decreased. Fox diet differed according to climatic and anthropogenic variables. Diet richness decreased with increasing temperature and precipitation. The incidence of small and large mammals decreased with increasing temperature. The incidence of birds and invertebrates decreased with increasing mean annual precipitation. Higher Human Footprint Index was associated with lower incidence of large mammals and higher incidence of birds and fruit in fox diet. Sampling method influenced fox diet estimation: estimated percentage of small and medium-sized mammals and fruit was lower in studies based on stomach contents, while large mammals were more likely to be recorded in studies of stomach contents than in studies of scats. Our study confirms the flexible and opportunistic dietary behaviour of foxes at the global scale. This behavioural trait allows them to thrive in a range of climatic conditions, and in areas with different degrees of human-induced habitat change. This knowledge can help place the results of local-scale fox diet studies into a broader context and to predict how foxes will respond to future environmental changes. <div></div>

opencc-zeroOct 2022View details →

Mechanisms of individual variation in large herbivore diets: Roles of spatial heterogeneity and state-dependent foraging

Many populations of consumers consist of relatively specialized individuals that eat only a subset of the foods consumed by the population at large. Although the ecological significance of individual specialization is recognized, it is difficult to document and its underlying mechanisms are poorly understood. Optimal foraging theory provides a useful framework for predicting how individuals might select different diets, positing that animals balance the 'opportunity cost' of stopping to eat an available food item against the cost of searching for something more nutritious; diet composition should be contingent on the distribution of food, and foragers should be more specialized when individuals have high energy reserves to spend searching for high-quality foods. We tested these predicted mechanisms of individual niche differences by quantifying environmental (resource heterogeneity) and organismal (nutritional condition) determinants of diet in a widespread browsing antelope (bushbuck, Tragelaphus sylvaticus) in an African floodplain-savanna ecosystem. We quantified individual diet breadth and composition using DNA metabarcoding of fecal samples collected repeatedly from 15 GPS-collared animals (6–14 samples per individual, median 12). Bushbuck diets were structured by spatial heterogeneity and constrained by individual conditions. We observed significant individual-level partitioning of food plants by bushbuck both within and between two adjacent habitat types (floodplain and woodland). Individuals with home ranges that were closer together and/or had similar vegetation structures (measured using LiDAR) ate more similar diets, supporting the prediction that heterogeneous resource distribution promotes individual differentiation. Individuals in good nutritional condition had significantly narrower diets (fewer plant taxa), searched their home ranges more intensively (intensity-of-use index), and had higher-quality diets (percent digestible protein) than those in poor condition, supporting the prediction that animals with greater endogenous reserves are more specialized because they can invest time in searching for nutritious foods. Our results support predictions from optimal foraging theory about the energetic basis of individual specialization and provide a potentially generalizable framework for understanding how individual niche width is governed by animal behavior and physiology in heterogeneous landscapes.

opencc-zeroApr 2018View details →

Supplementary material 1 from: Rosenfeld S, Marambio J, Ojeda J, Rodríguez JP, González-Wevar C, Gerard K, Contador T, Pizarro G, Mansilla A (2018) Trophic ecology of two coexisting Sub-Antarctic limpets of the genus Nacella: Spatio-temporal variation in food availability and diet composition of Nacella magellanica and N. deaurata in the Sub-Antarctic Ecoregion of Magellan . ZooKeys 738: 1-25. https://doi.org/10.3897/zookeys.738.21175

Tables S1–S11 : Explanation note: This is a DOC file with all the temporal information of the occurrence of the algae taxa in both localities, and all the information of the PERMANOVA analyzes used in this study.

opennotspecifiedMay 2018View details →

FIG. 2 in Spatial, Seasonal, and Sexual Variation in the Diet of Graptemys flavimaculata, a Threatened Turtle of the Pascagoula River System, Mississippi, USA

FIG. 2. Diets of male and female Graptemys flavimaculata from the Leaf (LR) and lower Pascagoula Rivers (PR) by season (Spring—dark gray, Summer—black, Fall—light gray). Prey items are sorted alphabetically with minor items not included.