Food partitioning among Malagasy primates

Summary Food partitioning among lemurs was studied in relation to food patch size and plant chemistry in the eastern rainforest and a western deciduous forest of Madagascar. Patch size (i.e. crown diameter of food trees) is significantly correlated with group body weight of different lemur species. But intraspecific variability is high and prevents effective species separation. Chemical analyses of more than 400 plant parts eaten by seven different lemur species revealed major differences in their food choice with respect to protein concentrations, condensed tannins and alkaloids. Among the leaf eating lemurs discriminant analysis segregates three groups à two species based on chemical characteristics of their food. Whereas differences in food chemistry are pronounced between groups they are lacking between the two species within each group. The two species of each group avoid interference competition by different activity rhythms. Actual competition for slowly renewable resources such as leaves and fruit, however, can not be reduced by different activities. Here interspecific differences in gross categories of food, food species composition and different habitat utilization due to other constraints may contribute to the possible coexistence of species. Thus interspecific differences in food selection in relation to primary and secondary plant chemicals is an integrated part of the mechanisms allowing several primate species to coexist in sympatry.     

Evolutionary responses to environmental heterogeneity in central american echinoid larvae: plastic versus constant phenotypes

Do changes in food resources lead to evolutionary changes in phenotypic plasticity or in different constant phenotypes? I addressed this question by studying plasticity of larval feeding arms for “geminate species pairs” in three echinoid genera. These closely related species were geographically isolated when the Panamanian Isthmus raised 2.8–3.1 million years ago, creating two different food level environments: high but variable food levels in the eastern Pacific versus chronically low food levels in the western Caribbean. I reared larvae of geminate species in different replicated food environments for 10 days postfertilization, collected morphological measurements of individual arm and body lengths, and calculated degrees of plasticity of relative arm length for each species. In contrast to previous studies with temperate echinoids, there was no significant plasticity of arm length in either the Pacific or Caribbean species considered here. Caribbean species, however, had significantly longer relative arm lengths than Pacific species, regardless of food levels. These results suggest that historical changes in food levels have led to the evolution of constant rather than plastic differences between Pacific and Caribbean echinoids. The evolution of plasticity may be limited by the timing of reproduction or by egg size in this system.     

Measuring fruit patch size for three sympatric indonesian primate species

Food availability is one of the basic factors affecting primate density and socioecology, but food availability is difficult to assess. Two different ways to obtain accurate estimates of food availability have been proposed: using phenology data or using the behaviour of animals. Phenology data can be refined by only including trees that are large enough to be used; including (potential) tree species in which by the concerned primate species forage; or including (fruiting) trees of these species that actually produce fruit. Alternatively, the sizes of the actually visited trees (foraging trees) give an estimate of fruit availability. These measures are compared for three sympatric primate species at the Ketambe Research Station, Sumatra, Indonesia: the Thomas langur, the long-tailed macaque and the orangutan. The sizes of fruiting trees and the foraging trees are larger than the potential trees. The sizes of the potential trees and of the fruiting trees are similar for the three primate species. This, however, is not reflected in the use of trees: the langurs forage on average in trees of similar size to those producing fruit, whereas the macaques and orangutans forage in trees larger than those producing fruit. The use of trees does not necessitate a different cut off point of included dbhs for the three compared primate species. The use of trees of different sizes, however, may be regulated by food competition. This indicates that sympatric primates make different foraging decisions and that behavioural measures of food availability will be less reliable.     

Genetic factors affecting food‐plant specialization of an oligophagous seed predator

Several ecological and genetic factors affect the diet specialization of insect herbivores. The evolution of specialization may be constrained by lack of genetic variation in herbivore performance on different food‐plant species. By traditional view, trade‐offs, that is, negative genetic correlations between the performance of the herbivores on different food‐plant species favour the evolution of specialization. To investigate whether there is genetic variation or trade‐offs in herbivore performance between different food plants that may influence specialization of the oligophagous seed‐eating herbivore, Lygaeus equestris (Heteroptera), we conducted a feeding trial in laboratory using four food‐plant species. Although L. equestris is specialized on Vincetoxicum hirundinaria (Apocynaceae) to some degree, it occasionally feeds on alternative food‐plant species. We did not find significant negative genetic correlations between mortality, developmental time and adult biomass of L. equestris on the different food‐plant species. We found genetic variation in mortality and developmental time of L. equestris on some of the food plants, but not in adult biomass. Our results suggest that trade‐offs do not affect adaptation and specialization of L. equestris to current and novel food‐plant species, but the lack of genetic variation may restrict food‐plant utilization. As food‐plant specialization of herbivores may have wide‐ranging effects, for instance, on coevolving plant–herbivore interactions and speciation, it is essential to thoroughly understand the factors behind the specialization process. Our findings provide valuable information about the role of genetic factors in food‐plant specialization of this oligophagous herbivore.     

Balkans’ Asteraceae Species as a Source of Biologically Active Compounds for the Pharmaceutical and Food Industry

Herbal drugs are a useful source of different bioactive compounds. Asteraceae species, as the most widespread vascular plants, can be used both as food and as medicine due to the great diversity of recorded chemical components – different phenolic compounds, terpenes, carotenoids, vitamins, alkaloids, etc. The Balkan Peninsula is characterized by great diversity of plants from Asteraceae family, including presence of rare and endemic species. In this review, results of the survey of chemical composition and biological activity, mainly focusing on antioxidant, antimicrobial and anticancer effects of selected Balkans’ Asteraceae species were provided. In addition, information on edible plants from Asteraceae family is presented, due to growing interest for the so‐called ‘healthy diet’ and possible application of Balkans’ Asteraceae species as food of high nutritional value or as a source of functional food ingredients.     

高黎贡山赧亢白眉长臂猿春季食物选择

2007年3月9日—4月28日,在高黎贡山赧亢跟踪观察白眉长臂猿(Hoolock hoolock)的春季食性及取食行为,将其行为分为食果、食果汁和食叶。采用瞬时扫描法记录白眉长臂猿的取食行为,取食的种类、部位和地点等。在其活动区域内,以取食树为中心设置20m×20m的利用样方和以随机方式设置同样大小的可利用样方各19个。在样方内收集与取食树及食物资源相关的6个因子的数据。统计食物种类和资源量、选择指数、取食点的选择性等。结果表明,赧亢白眉长臂猿春季取食的食物共10种,其中果实类植物3种,果汁类植物1种,嫩叶类植物6种。10种食物中,白眉长臂猿对印度木荷(Schima khasiana)的果实和缅甸木莲(Maglietia haokeri)的嫩叶呈弱选择,对其他8种食物资源均呈强选择。Mann-WhitneyU-检验结果表明,利用样方和可利用样方间的食物资源量及食物种类数均差异极显著,以利用样方的资源量大,每一样方食物种类较多。果实是赧亢白眉长臂猿春季的主要食物资源,而嫩叶是补充。呈强选择的食物并不一定是取食频次高的食物;反之,取食频次高的食物也不一定呈强选择。白眉长臂猿常选择易处理的果实和粗灰分含量少的嫩叶,且果实是它摄取水分的主要来源。白眉长臂猿通常选择食物资源和种类相对集中的区域取食,这可以减少动物因寻找食物所耗费的能量,同时获得多种食物,满足其生理对营养的需求。     

Four years host–parasitoid food web: testing sampling effort on trophic levels

Incomplete sampling is a major problem affecting data quality with respect to food webs. We described a host–parasitoid food web based on data from four years of sampling, evaluated the dataset robustness of the food web, and tested the hypothesis that different trophic levels require different sampling efforts. We sampled Senegalia tenuifolia fruits at eight sampling sites in three areas, during four years (2011–2014) in the Brazilian cerrado (savanna). We recorded 26 insect species in three trophic levels associated with S. tenuifolia. For species accumulation curves, all insect trophic levels, areas and years reached the asymptote, except for one area. The cumulative species richness in each trophic level suggested that the third level (primary parasitoid) should be sampled for a longer time than the second and fourth levels, supporting our hypothesis. In conclusion, the sampling effort employed was sufficient to assess most of the insect species richness, and provided a high-quality and well-represented host-parasitoid food web, even though trophic levels require different efforts.     

中国秋海棠属植物的传统利用

秋海棠属植物除了具有较高的观赏价值外,在中国还作为药用、食用、饮料和饲料等被利用。本文应用民族植物学研究方法,通过野外调查、文献和标本收集整理和研究,共记载了中国产26种秋海棠属植物被作为药用、食用、饮料和饲料加以利用。在所记载的26种国产秋海棠属植物中,有24种作药用,8种作食用(蔬菜)或饮料,5种作饲料。3种作饮料的种类在其自然分布地被广泛利用。9种秋海棠作为多种用途加以利用,其中8种既被作为药用、食用和饮料,也被作为饲料加以利用。本研究还表明,国产秋海棠属植物中,有些种类由于过度采集利用或其它因素已变得稀有或濒危。由此提出,合理开发利用和有效保护应成为今后中国秋海棠属植物研究的重要内容。     

Global synthesis suggests that food web connectance correlates to invasion resistance

Biological invasions are a key component of global change, and understanding the drivers of global invasion patterns will aid in assessing and mitigating the impact of invasive species. While invasive species are most often studied in the context of one or two trophic levels, in reality species invade communities comprised of complex food webs. The complexity and integrity of the native food web may be a more important determinant of invasion success than the strength of interactions between a small subset of species within a larger food web. Previous efforts to understand the relationship between food web properties and species invasions have been primarily theoretical and have yielded mixed results. Here, we present a synthesis of empirical information on food web connectance and species invasion success gathered from different sources (estimates of food web connectance from the primary literature and estimates of invasion success from the Global Invasive Species Database as well as the primary literature). Our results suggest that higher‐connectance food webs tend to host fewer invaders and exert stronger biotic resistance compared to low‐connectance webs. We argue that while these correlations cannot be used to infer a causal link between food web connectance and habitat invasibility, the promising findings beg for further empirical research that deliberately tests for relationships between food web connectance and invasion.     

The phylogenetic component of food web structure and intervality

Despite the exceptional complexity formed by species and their interactions in ecological networks, such as food webs, regularities in the network structures are repeatedly demonstrated. The interactions are determined by the characteristics of a species. The characteristics are in turn determined by the species’ phylogenetic relationships, but also by factors not related to evolutionary history. Here, we test whether species’ phylogenetic relationships provides a significant proxy for food web intervality. We thereafter quantify the degree to which different species traits remain valuable predictors of food web structure after the baseline effect of species’ relatedness has been removed. We find that the phylogenetic relationships provide a significant background from which to estimate food web intervality and thereby structure. However, we also find that there is an important, non-negligible part of some traits, e.g., body size, in food webs that is not accounted for by the phylogenetic relationships. Additionally, both these relationships differ depending if a predator or a prey perspective is adopted. Clearly, species’ evolutionary history as well as traits not determined by phylogenetic relationships shapes predator-prey interactions in food webs, and the underlying evolutionary processes take place on slightly different time scales depending on the direction of predator-prey adaptations.     

The importance of mangroves, mud and sand flats, and seagrass beds as feeding areas for juvenile fishes in Chwaka Bay, Zanzibar: gut content and stable isotope analyses

The relative importance of bay habitats, consisting of mangrove creeks and channel, seagrass beds, and mud and sand flats, as feeding grounds for a number of fish species was studied in Chwaka Bay, Zanzibar, Tanzania, using gut content analysis and stable isotope analysis of carbon and nitrogen. Gut content analysis revealed that within fish species almost the same food items were consumed regardless of the different habitats in which they were caught. Crustaceans (mainly copepods, crabs and shrimps) were the preferred food for most zoobenthivores and omnivores, while fishes and algae were the preferred food for piscivores and herbivores, respectively. The mean δ¹³C values of fishes and food items from the mangrove habitats were significantly depleted to those from the seagrass habitats by 6·9 and 9·7‰ for fishes and food items, respectively, and to those from the mud and sand flats by 3·5 and 5·8‰, respectively. Fishes and food items from the mud and sand flats were significantly depleted as compared to those of the seagrass habitats by 3·4 and 3·9‰, for fishes and food, respectively. Similar to other studies done in different geographical locations, the importance of mangrove and seagrass themselves as a primary source of carbon to higher trophic levels is limited. The different bay habitats were all used as feeding grounds by different fish species. Individuals of the species Gerres filamentosus , Gerres oyena , Lethrinus lentjan , Lutjanus fulviflamma , Pelates quadrilineatus and Siganus sutor appeared to show a connectivity with respect to feeding between different habitats by having δ¹³C values which were in-between those of food items from two neighbouring habitats. This connectivity could be a result of either daily tidal migrations or recent ontogenetic migration.     

High food quality of prey lowers its risk of extinction

The mineral and biochemical food quality of prey may limit predator production. This well‐studied direct bottom–up effect is especially prominent for herbivore–plant interactions. Low‐quality prey species, particularly when defended, are generally considered to be less prone to predator‐driven extinction. Undefended high‐quality prey species sustain high predator production thereby potentially increasing their own extinction risk. The food quality of primary producers is highly species‐specific. In communities of competing prey species, predators thus may supplement their diets of low‐quality prey with high‐quality prey, leading to indirect horizontal interactions between prey species of different food quality. We explore how these predator‐mediated indirect interactions affect species coexistence in a general predator–prey model that is parametrized for an experimental algae– rotifer system. To cover a broad range of three essential functional traits that shape many plant–herbivore interactions we consider differences in 1) the food quality of the prey species, 2) their competitive ability for nutrient uptake and 3) their defence against predation. As expected, low food quality of prey can, similarly to defence, provide protection against extinction by predation. Counterintuitively, our simulations demonstrate that being of high food quality also prevents extinction of that prey species and additionally promotes coexistence with a competing, low‐quality prey. The persistence of the high‐quality prey enables a high conversion efficiency and control of the low‐quality prey by the predator and allows for re‐allocation of nutrients to the high‐quality competitor. Our results show that high food quality is not necessarily detrimental for a prey species but instead can protect against extinction and promote species richness and functional biodiversity.     

The reduction of food web robustness by parasitism: fact and artefact

A robust food web is one which suffers few secondary extinctions after primary species losses. While recent research has shown that a food web with parasitism is less robust than one without, it still remains unclear whether the reduction in robustness is due to changes in network complexity or unique characteristics associated with parasitism. Here, using several published food webs, simulation experiments with different food web models and extinction scenarios were conducted to elucidate how such reduction can be achieved. Our results show that, regardless of changes in network complexity and preferential parasitism, the reduction in food web robustness is mainly due to the life cycle constraint of parasites. Our findings further demonstrate that parasites are prone to secondary extinctions and that their extinctions occur earlier than those involving free-living species. These findings suggest that the vulnerable nature of parasites to species loss makes them highly sensitive indicators of food web integrity.     

Digestive and feeding characteristics of the chondrosteans

Synopsis Structure and function of the digestive system and feeding characteristics of the chondrosteans are reviewed. Although the group exhibits a wide diversity of feeding habits including piscivory, benthophagy, and planktivory, they are principally carnivores throughout their life history. Examination of digestive system structure reveals the basic structure to be similar among the species with some modification to accomodate the different food types. For the species studied, composition of the adult digestive enzyme complement is consistent with the carnivorous habits with proteases dominating and only low levels of carbohydrase activity. There are three secretory phases during development of the digestive system. Each corresponds with different food habits of the different life-history intervals. Vision is apparently not utilized for feeding in any interval. Instead food is recognized and located primarily by gustation, olfaction, textural qualities, and, possibly, electroreception.     

Mechanical functions of setae from the mouth apparatus of seven species of decapod crustaceans

The mouthpart setae of seven species of decapods were examined with macro-video recordings and scanning electron microscopy. The general mechanical (nonsensory) functions of the different mouthparts are described and an account of their setation is given. This offers the possibility to determine the mechanical functions of the different types of setae. Pappose setae do not participate in food handling but in general make setal barriers. Plumose setae likewise do not contact food objects but assist in current generation. Papposerrate setae are rare but they were seen to assist in pushing food particles into the mouth. Serrulate setae are very common and mainly participate in gentle food handling and grooming. Serrate setae are used for more rough food manipulation and grooming. The roughest shredding, tearing, and manipulation of prey items are handled by the cuspidate setae. Simple setae seem to be divided into two populations with very different functions. On the maxillipeds of Panulirus argus they are used for shredding, tearing, and holding the food objects, but on the basis of maxilla 2 of three other species they appear to have very little mechanical influence and only when handling small prey items. The functional scheme seems to be consistent within the Decapoda.     

Feeding of an Iberian stream cyprinid assemblage: seasonality of resource use in a highly variable environment

Food resource use by seven cyprinids from an Iberian stream was analysed over 9 months. Differences in food resource use were found both between species and within species between seasons. Plant material was a more important food for carp, nase, goldfish and barbel than for gudgeon, roach and chub, irrespective of the season. Chironomid larvae were the staple animal food for the former five species throughout the year. Roach and chub, especially the latter, displayed large seasonal variations in prey use, with chironomid larvae only being important during autumn. Ephemerellid nymphs and ephemeropteran imagos dominated the animal diet of chub during spring and summer, respectively. Dipteran adults and Formicidae were the most important prey for roach during spring and summer, with other common prey being ephemerellid nymphs and hydropsychid larvae. Food resource overlap among the three dominant species (roach, barbel and chub) displayed a large seasonal variation. High overlaps were observed during autumn when these species used the same resources. During summer overlaps were much lower with each species specialising on different prey. The remaining less abundant species had large diet overlaps amongst themselves and with barbel, over all seasons. It is suggested that morphological constraints, habitat partitioning and temporal changes in food resource limitation may be involved in producing these patterns of food resource use.     

Horizontal transmission of Wolbachia in a Drosophila community

Abstract.  1.  Wolbachia bacteria are reproductive parasites of arthropods and infect an estimated 20% of all insect species worldwide. In order to understand patterns of Wolbachia infection, it is necessary to determine how infections are gained or lost. Wolbachia transmission is mainly vertical, but horizontal transmission between different host species can result in new infections, although its ecological context is poorly understood. Horizontal transmission is often inferred from molecular phylogenies, but could be confounded by recombination between different Wolbachia strains.
2. This study addressed these issues by using three genes: wsp , ftsZ , and groE , to study Wolbachia infections in fruit- and fungus-feeding Drosophila communities in Berkshire, U.K.
3. Identical sequences were found for all three genes in Drosophila ambigua and Drosophila tristis. This suggests horizontal transmission of Wolbachia between these two previously unstudied Drosophila species, which may be the result of the two host species sharing the same food substrates or parasites.
4.  Wolbachia infections might be lost from species due to curing by naturally occurring antibiotics and the presence of these is likely to vary between larval food substrates.
5. It was investigated whether Wolbachia incidence was lower in fungus-feeding than in fruit-feeding Drosophila species, but no significant difference based on food substrate was found.