The dietary basis for temporal partitioning: food habits of coexisting Acomys species

Two rodent species of the genus Acomys coexist on rocky terrain in the southern deserts of Israel. The common spiny mouse (A. cahirinus) is nocturnally active whereas the golden spiny mouse (A. russatus) is diurnally active. An early removal study suggested that competition accounts for this pattern of temporal partitioning: the golden spiny mouse is forced into diurnal activity by its congener. Theoretically, temporal segregation should facilitate coexistence if the shared limiting resources differ at different times (primarily among predators whose prey populations have activity rhythms), or if they are renewed within the period of the temporal segregation. We studied food preferences of the two Acomys species in a controlled cafeteria experiment in order to assess resource overlap and the potential for competition for food between the two species. We found no significant difference in food preferences between species. The dietary items preferred by both were arthropods. We also carried out a seasonal study of the percentage and identity of arthropods taken in the field by individuals of the two species. Individuals of both species took on annual average a high percentage of arthropods in their diets. Seasonal diet shifts reflect seasonal abundance of arthropods at Ein Gedi during day and night. Diurnal activity may also reduce interspecific interference competition between A. russatus and A. cahirinus. However, the strong interspecific dietary overlap in food preference, the heavy reliance on arthropods in spiny mouse diets, and the seasonal and circadian differences in arthropod consumption suggest that prey partitioning may be a viable mechanism of coexistence in this system. Received: 6 July 1998 / Accepted: 10 May 1999     

Food and feeding of three Distichodus species (Pisces: Characiformes) in Lake Kainji,Nigeria

The food and feeding of three Distichodus species in Lake Kainji, Nigeria was studied. Sixty 140 and 528 specimens of Distichodus brevipinnis, D. engycephalus and D. rostratus respectively were examined. All three species were exclusively herbivorous. Their feeding was intense in the evening until dusk but declined during the day. All exhibited some seasonal variation in their food preferences.     

Diapause in the seasonal cycle of stink bugs (Heteroptera,Pentatomidae) from the Temperate Zone

The paper reviews the data on diapause and related phenomena in stink bugs (Heteroptera: Pentatomidae). Using stink bugs as examples, the consecutive stages of the complex dynamic process of diapause (such as diapause preparation, induction, initiation, maintenance, termination, post-diapause quiescence, and resumption of direct development) are described and discussed. Out of 43 pentatomid species studied in relation to diapause in the Temperate Zone up to date, the majority (38 species) overwinter as adults, two species—as eggs, and another two species—as nymphs. Pentatoma rufipes is believed to be able to overwinter at different stages of its life cycle. Less than 5 % of pentatomid species are probably able to overwinter twice. Only five species have obligate diapause, others have the facultative one. Day-length and temperature are the main diapause inducing factors in the majority of species. The role of food in the control of seasonal development is essential in the pentatomid species feeding on plant seeds. In different species, different stages are sensitive to day-length. Some pentatomids retain sensitivity to photoperiod even after diapause, others lose it and become photo-refractory (temporarily or permanently). In Pentatomidae, such seasonal adaptations as photoperiodic control of nymphal growth rates, seasonal body colour change, migrations, and summer diapause (aestivation) are widely represented, whereas wing and/or wing muscle polymorphism has not been reported yet. In the subfamily Podopinae, induction of facultative reproductive winter diapause is under the control of photoperiod and temperature. All species feed on seeds and their seasonal development to a great extent reflects availability of food. However, the same food preferences and pattern of seasonal development are also characteristic to many species from the subfamily Pentatominae. All species of the subfamily Asopinae are predators. Among them, Picromerus bidens and Apateticus cynicus have obligate embryonic winter diapause, which is rear among true bugs. At the same time, A. cynicus and Podisus maculiventris belong to the same tribe but have different types of diapause: obligate embryonic diapause in A. cynicus and facultative adult diapause in P. maculiventris. Other Asopinae species studied up to date have facultative adult diapause controlled by photoperiod and temperature with probably only one exception: in Andrallus spinidens, adult diapause is controlled by temperature, and photoperiod plays only a secondary role. Thus, in spite of the similar habits and feeding types among Asopinae, the species of this subfamily have different types of diapause and the latter is controlled by different factors. In the subfamily Pentatominae, most species overwinter as adults and induction of their diapause is controlled by the long-day type photoperiodic response, in spite of the differences in their feeding preferences (within phytophagy). However, there are some exceptions in this subfamily, too: Palomena prasina, P. angulosa and Menida scotti have obligate diapause, which conditions univoltinism in these pentatomids. In M. scotti, only females have obligate adult diapause, whereas males remain physiologically active through the whole winter, this pattern being unusual for Heteroptera. The univoltine seasonal cycle of this species with summer diapause (aestivation) and apparent migrations is similar to that of shield bugs (Scutelleridae). According to the analysis of seasonal development, the evolution of seasonal adaptations in Pentatomidae does not directly reflect their phylogeny. However, individual genera, small tribes or even subfamilies have similar complexes of seasonal adaptations. At the same time, Pentatominae is a large and apparently collected taxon, but most of species in this subfamily have the same facultative adult diapause.     

Comparative ecology of Gammarus pulex (L.) and Asellus aquaticus (L.) II: fungal preferences

This paper continues to explore niche differentiation in Gammarus pulex and Asellus aquaticus by analysis of their food preferences. Individuals from both species discriminated between leaf discs colonized by different fungal species and exhibited strong preferences for Anguillospora longissima and Heliscus lugdunensis. Fungal preferences were not correlated with the relative abundance of fungi in the field and there was considerable intra-population variability in food preferences — both between individuals and for the same individual through time. Niche overlap between animals from all four study populations was high and there was no evidence of differences in the potential trophic niches of animals from sympatric and allopatric populations.     

Seasonal changes and alternation of food plant preference in some mesophyll-feeding leafhoppers

Summary The life histories of two bivoltine mesophyll-feeding leafhoppers, Lindbergina aurovittata (Douglas) and Edwardsiana rosae (L.), in South Wales are described. L. aurovittata alternates between evergreen Rubus and Quercus in the first generation and various deciduous broad-leaved trees in the second. Experiments on nymphal food preferences and adult oviposition behaviour show that nymphs of both generations tend to prefer older to younger leaves, but show little species specificity. However, adults are discriminating in oviposition preferences, which change regularly and completely in alternating generations. Similar results were obtained with E. rosae. Such obligate seasonal changes in host preferences and utilization are well known amongst aphids, but previously have not been reported in leafhoppers.     

Seasonal variation in food availability and relative importance of dietary items in the Gambian epauletted fruit bat (Epomophorus gambianus)

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The feeding ecology of Rüppell's Parrot,Poicephalus rueppellii,in the Waterberg,Namibia

Rüppell's Parrot, Poicephalus rueppellii, inhabits a markedly seasonal environment in Namibia and feed on plant seeds that respond to that seasonality. Although Rüppell's Parrots were seen feeding at 37 plant species they showed clear preferences. The diet was dominated by seeds, but also included other fruit, flowers (especially nectar), leaves, arthropods and bark. The arthropods were the larvae of lepidoptera, coleoptera and hemiptera, and spiders. Feeding was observed on 19 plant species during a year period and the proportion of observations/species/month was determined. Terminalia prunioides, Albizia anthelmintica and Acacia er/o/oba represent preferred foods and provided most of the diet at particular times of the year. The fruiting periods of most plants were highly seasonal and the parrots changed diet frequently; however, T. prunioides holds its pods all year round and was used more than any other species. Monthly diet was also analysed by food type. Seeds formed the greatest part of the diet from December to August, but flowers and insects formed a major part of the diet prior to the onset of the rains. In particular, A. anthelmintica provided nectar and harboured insects when there was very little other food available. It may be critically important in the east of this parrot's distribution where the winter-fruiting Faidherbia albida is not found. For two species there Was some evidence that soft, slightly unripe drupes were preferred over riper, harder fruits. Rüppell's Parrot is omnivorous but mostly a seed predator. It survives in a highly seasonal environment by exploiting a wide range of food items.     

Dietary overlap of grasshoppers on sandhill rangeland in northeastern Colorado

Summary Overlap in the diets of 14 species of grasshoppers on mixed-grass prairie in northeastern Colorado was estimated by microscopic examination of crop contents. Food availability estimates, taken by a weight-estimate method, facilitated the determination of food preferences. Two cases of high overlap in diets and period of habitat occupancy occurred between species which consumed equal or almost equal numbers of different foods (foodniche breadth) and had almost identical foraging behavior. The first case occurred early in the season between Xanthippus corallipes and Arphia conspersa with foodniche breadths of 14 and 11, respectively. The second case occurred later in the season between Amphitornus coloradus and Trachyrhachys kiowa both of which have foodniche breadths of 6. The amount of movement between plants while feeding was equal or almost equal in both cases, thus we observed high dietary overlap between species with equal ecological efficiencies. Dietary overlap between the 14 grasshopper species decreased as foodniche dimensions increased and the grasshopper population as a whole utilized each food resource approximately proportional to its relative abundance. Factors influencing the interpretation and importance of dietary overlap in this study included 1. non-synchronous life cycles, 2. seasonal changes in diets and food preferences, 3. complexity of the food resources, 4. variations in foodniche dimensions among grasshopper species, and 5. variations in diets between males and females within a species. Our findings agree with MacArthur and Levins theory that the number of competing species which can coexist is proportional to the total range of the environment divided by the niche breadth of the species.     

A population genomic scan in Chorthippus grasshoppers unveils previously unknown phenotypic divergence

Understanding the genetics of speciation and the processes that drive it is a central goal of evolutionary biology. Grasshoppers of the Chorthippus species group differ strongly in calling song (and corresponding female preferences) but are exceedingly similar in other characteristics such as morphology. Here, we performed a population genomic scan on three Chorthippus species (Chorthippus biguttulus, C. mollis and C. brunneus) to gain insight into the genes and processes involved in divergence and speciation in this group. Using an RNA‐seq approach, we examined functional variation between the species by calling SNPs for each of the three species pairs and using F_ST‐based approaches to identify outliers. We found approximately 1% of SNPs in each comparison to be outliers. Between 37% and 40% of these outliers were nonsynonymous SNPs (as opposed to a global level of 17%) indicating that we recovered loci under selection. Among the outliers were several genes that may be involved in song production and hearing as well as genes involved in other traits such as food preferences and metabolism. Differences in food preferences between species were confirmed with a behavioural experiment. This indicates that multiple phenotypic differences implicating multiple evolutionary processes (sexual selection and natural selection) are present between the species.     

Waterfowl management and diet of the salt marsh harvest mouse

The salt marsh harvest mouse (Reithrodontomys raviventris) is an endangered species, endemic to the marshes of the San Francisco Bay, California, USA. This species is thought to feed primarily on pickleweed (Salicornia pacifica), although its diet is poorly understood, and a large proportion of remaining habitat for salt marsh harvest mice is managed for non-pickleweed vegetation to provide habitat for waterfowl. Using 2 sets of cafeteria trials, we tested food preferences of the salt marsh harvest mouse when offered a variety of plants and invertebrates from the Suisun Marsh, Solano County, California. In a set repeated menu, and unique seasonal menus, salt marsh harvest mice showed strong preferences for food types commonly grown for waterfowl, and also for non-native plants; in contrast, pickleweed was the most preferred during only some of the set and some of the seasonal trials. These results suggest that salt marsh harvest mice have a more flexible diet than previously thought, and will allow land managers in areas such as the Suisun Marsh to promote the growth of plants that provide foods that are preferred by both waterfowl and salt marsh harvest mice. © 2019 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Food preference,food quality and diets of three herbivorous gastropods (Trochidae: Tegula) in a temperate kelp forest habitat

Summary The relationship between food preference and food quality (i.e. a food's contribution to growth and reproductive development) was examined in the laboratory for 3 species of herbivorous kelp forest gastropods (Tegula). The preference hierarchies of the 3 Tegula for 6 common algal species are the same: giant kelp (Macrocystis) is the most preferred food and brown algae are consumed at higher rates than red algae. Despite their strong preference for Macrocystis, the 3 species had significantly greater growth and/or reproductive development on a mixed-algae diet than on either brown or red algae alone. Laboratory preferences of the snails did not correspond closely with caloric content, estimated availability or quality of the algal species used in this study. However, the 3 Tegula are subject to strong benthic predation and Macrocystis provides an important spatial refuge in nature. The potential role of non-nutritional factors such as predator avoidance on the formation of food preferences is discussed.     

Herbivory on calcicolous lichens: different food preferences and growth rates in two co-existing land snails

A total of 32 calcicolous lichen species, one alga and one bryophyte were recorded on a limestone wall in the grassland Great Alvar on the Baltic island of Öland, Sweden. Fourteen (41%) of these 34 species and free-living cyanobacteria showed herbivore damage, most probably due to grazing by the land snails Chondrina clienta and Balea perversa which inhabited the limestone wall. Three laboratory experiments were conducted to examine the food preferences of individuals of C. clienta and B. perversa collected at this site and to evaluate any association between their preference and the net food quality of the lichens to the snails. Chondrina clienta and B. perversa exhibited food preferences, which differed significantly between species. Within species, variation in food choice was similar among individuals. This indicates that snail populations may be composed of polyphagous individuals with similar food preferences. Different lichen species were of different net food quality to the snails as indicated by growth rate differences. In both snail species the most preferred lichen species of the choice experiment caused the largest weight increase in juveniles, viz. Caloplaca flavovirescens for C. clienta and Aspicilia calcarea for B. perversa. This suggest that the snail species studied differ in their abilities to deal with secondary compounds and physical characteristics of certain lichens or that they can utilize the energy and nutrients of these lichens to a different extent. It is suggested that differential food preferences might reduce the intensity of interspecific competition for resources (lichens) between C. clienta and B. perversa.     

Seasonal Food Use Strategies of <Emphasis Type="Italic">Semnopithecus vetulus nestor</Emphasis>, at Panadura and Piliyandala,Sri Lanka

Field studies on Semnopithecus vetulus have shown high folivory and the ability to feed heavily on mature leaves, which are constantly available. In research spanning 19 mo, I examined the feeding behavior of 2 free-ranging groups of Semnopithecus vetulus nestor in home gardens and rubber monocultures at Panadura (PT1 group) and Piliyandala (R1 group), Sri Lanka. Overall, results showed that >80% of their diet comprised seasonal plant parts, largely fruits. Despite differences in spatial and temporal food availability in their respective habitats, seasonal plant parts dominated the diets of both groups except briefly (2 mo) for R1 when mature leaf petioles were the main plant food. Both groups increased their use of seasonal foods with heightened seasonal food availability, and increased dietary diversity with declining use of their highest-ranked specific item of diet: fruits of Artocarpus heterophyllus (jakfruit, Moraceae). PT1, which was in a species-rich environment, maintained a high intake of seasonal foods year round by exploiting a large number of species, mainly for fruits. In contrast, R1, in a habitat with significantly lower tree species richness, had a less diverse diet but maintained an equally high intake of seasonal foods, primarily fruits and seeds, by exploiting a few species heavily. My study also highlights the dietary flexibility of a single colobine species in space and time. Such information is useful for conservation planning because rapidly occurring changes are taking place in natural colobine habitats.     

广西扶绥破碎化生境中黑叶猴的食物种类多样性和季节性重叠

动物使用生境中食物种类的方式对其适应性有重要的影响。为了研究黑叶猴在破碎化栖息地中利用食物的方式,2006年1—12月,采用焦点动物取样法和连续记录技术于每月初连续观察8 d,记录破碎化栖息地中黑叶猴取食的种类和时间,分析其食物多样性和月份间种类的重叠度。结果表明,黑叶猴年均食物多样性指数为3.03(范围1.93—2.62),且多样性指数在各月间没有显著的差异(One-sample K-S Test,P=0.99),说明黑叶猴在各月份中取食的食物种数相似,不同季节利用食物种数的变异程度不大。在所有的食物种类中,仅两种食物青檀Pteroceltis tatarinowii和潺槁树Litsea glutinosa在12个月份都被取食,其他种类则表现了月份间明显的季节性替代。各月份间食物种类的相似性在0.42(3—4月)和0.75(9—10月)之间变化。黑叶猴对破碎化生境中食物种类的利用方式是:首先利用常年均有的食物种类以保证食物来源稳定,同时选择性地利用新出现的种类,使食物种类多样化,满足不同的营养需求。     

Seasonal flooding regime and ecological traits influence genetic structure of two small rodents

Although codistributed species are affected by the same abiotic factors, such as rivers and seasonal flooding regimes, ecological traits, such as locomotion habits and habitat preferences, may also influence differences in levels of genetic diversity and differentiation. We examined population genetic structure and diversity of Hylaeamys megacephalus and Oecomys aff. roberti, two cricetid rodent species from the mid‐Araguaia River in central Brazil, using mitochondrial DNA sequence data. Specifically, we aim to test whether the Araguaia River acts as a barrier to the gene flow of these two species and to assess how ecological traits, such as locomotion habits and habitat preferences, may influence differences in levels of genetic diversity and differentiation. As both species occur in flooded forests, neither showed genetic differences related to river banks. Oecomys aff. roberti showed stronger population structure that appears to be associated with isolation by distance. This arboreal species maintained stable populations in the Araguaia River, while the terrestrial H. megacephalus was more affected by seasonal floods, resulting in a genetic signature of population expansion. Our initial predictions were largely supported by our results given that locomotion habits and habitat preferences of each species appears to have played a role on the genetic structure of these two sympatric rodent species.     

Importance and seasonality of vegetable consumption and marketing in Burkina Faso

The use of vegetables in two rural communities in Burkina Faso is quantified through the use of food diaries kept by 13 households during one year. Interviews on preferences, field registration, and a market survey supplement the diaries. The use of wild species is concentrated onParkia biglobosa, Corchorus spp.,Adansonia digitata, andBombax costatum. At least five other wild species are mentioned as important but very rarely occur in the diet, indicating the usefulness of diaries compared to interviews.Capsicum frutescens, Abelmoschus esculentus, Allium cepa, andSolanum lycopersicon are the most commonly used cultivated species. Wild vegetables constitute 35% and 59% of the total vegetable consumption in the two communities. Most products are highly seasonal in supply and prices vary accordingly. Households compensate for the seasonality by drying products, but stocks are often insufficient and vegetable purchases needed. Many of the vegetable species studied should be integrated in agricultural research and extension programs.     

Ecological correlates to activity and habitat use of two prosimian primates: Eulemur rubriventer and Eulemur fulvus rufus in Madagascar

In this paper, I provide data on the possible effects of group size and seasonal changes in food availability on the activity and habitat use patterns of two species of prosimian primate: the rufous lemur (Eulemur fulvus rufus) and the red-bellied lemur (Eulemur rubriventer). General and subtle seasonal differences were observed between lemur species in (1) group size and composition, (2) activity profiles, and (3) habitat use. Rufous lemur groups were larger (mean = 8 individuals) and contained more adults than red-bellied lemur groups (mean = 3 individuals). The overall degree and distribution of diurnal activity differed between lemur species and varied within species with seasonal changes in food availability. In general, rufous lemurs traveled more often than red-bellied lemurs. During food scarcity, both species increased the amount of time spent feeding, although peak feeding and traveling times differed. Both species also preferred horizontal substrates; however, during food scarcity, red-bellied lemurs used terminal branches more often while feeding than rufous lemurs. In addition, red-bellied lemurs used the lower middle story forest and rested in taller, upper canopy trees more often than rufous lemurs. Differences in activity and habitat use patterns between lemur species were more related to seasonal changes in food availability than overall differences in group size. These behavioral patterns may represent different strategies used by each lemur species to avoid directly competing for similar resources during times of food scarcity. © 1996 Wiley-Liss, Inc.     

On the coexistence of three predatory stonefly species in a central Japanese stream

Three large-bodied stonefly species (Paragnetina tinctipennis, Oyamia lugubris, and Kamimuria tibialis) coexist in a central Japanese stream. These species have been classified as predators. Here we study their microhabitat use while focusing on the physical environments, physiological activity, and food resources. We show that Paragnetina uses a niche with faster currents than other species throughout the year. Oyamia has seasonal flexibility in microhabitat preference, physiological activity, and food resources. Kamimuria is a rather stable species, independent of seasonal patterns.     

Golden monkey ranging in relation to spatial and temporal variation in food availability

Understanding the determinants of a species’ range use aids in understanding their ecological requirements, which in turn facilitates designing effective conservation strategies. The ranging behaviour of golden monkeys (Cercopithecus mitis kandti) in Mgahinga Gorilla National Park, Uganda was studied from January 2003 to February 2004 to establish habitat preferences. In each 0.25 ha grid cell in the group’s home range we quantified the basal area of food trees (n = 12,133 trees), measured bamboo (Arundinaria alpina) stems (n = 103,548), and estimated vine and shrub coverage. The evaluation of habitat preferences was facilitated by the fact that only five plant species, plus invertebrates (7.5%) constituted 96.4% of the group’s foraging effort; this included bamboo (59.9%), Maesa lanceolata (18.7%), Hypericum revolutum (6.8%), Galiniera saxifraga (2.1%) and Ilex mitis (1.4%). Phenology data were collected for all five food tree species, three vines, and two shrubs. Range use generally followed food tree basal area distribution and not the distribution of bamboo, with the abundance of M. lanceolata being more closely associated with home range use than any other food plant. Bamboo was ubiquitous in distribution and a vital year‐round resource for golden monkeys, which they combined with other food items to meet their nutritional requirements. Illegal bamboo or tree extraction both pose a serious threat to the conservation of the golden monkey, but activities that affect food tree abundance will likely have the most influence on monkey persistence.     

The role of the antennae and maxillary palps in mediating food preference by larvae of the tobacco hornworm, Manduca sexta

The role of antennae and maxillary palps in mediating food preferences by Manduca sexta (Johan.) (Lepidoptera: Sphingidae) was examined. Fifth‐instar larvae, having different chemosensory organs remaining after microsurgery, were tested in two‐choice feeding assays using three solanaceous host species Lycopersicon esculentum (Mill.), Datura innoxia (Mill.), and Solanum pseudocapsicum (L.), an acceptable non‐host Raphanus sativus (L.) (Cruciferae), and an unacceptable non‐host Pelargonium hortorum (L.H. Bailey) (Geraniaceae). Larvae had a choice between leaf discs of two plant species or between one species and moist filter paper discs (water). The antennae are fully competent in mediating normal (unimpaired) food preferences for S. pseudocapsicum vs. water and P. hortorum vs. water. Thus, the antennae alone can mediate both acceptance and rejection behaviour. The latter is the first report of such a function in M. sexta. The antennae are partly competent (reduced preference) for S. pseudocapsicum vs. P. hortorum. No antennal competence could be demonstrated using the other plant species tested. The antennae alone are either partly needed (R. sativus vs. water) or not necessary to elicit normal food preferences for the plant species tested. The maxillary palps are fully competent in mediating normal food preference for S. pseudocapsicum vs. water, and D. innoxia vs. water. The palps are partly competent for S. pseudocapsicum vs. P. hortorum and incompetent for the other plant species tested. Thus, the maxillary palps alone could only mediate acceptance behaviour in this study. The need of the maxillary palps in normal food preferences could not be demonstrated. Interestingly, the maxillary palps alone can mediate food preferences for two normally rejected plants, R. sativus and P. hortorum. Similar results are reported for two other non‐host plant species, Vigna unguiculata (Walp.) (Leguminosae) and Vinca rosea (L.) (Apocynaceae). Perhaps, the maxillary palps inform M. sexta mostly about feeding stimulatory chemicals common to most plant species.