scholarly journals The Induction of Larval Resource Preference in Heterogeneous Habitats

2018 ◽  
Author(s):  
Vrinda Ravi Kumar ◽  
Swastika Issar ◽  
Deepa Agashe

ABSTRACTAnimals often have to evaluate and choose between multiple food sources in their habitat, and these potentially complex decisions can have a large impact on their fitness. Among other factors, previous experience with an alternative resource can significantly increase subsequent preference for the resource ("induction of preference"). Such induction of resource preference is particularly relevant in spatially or temporally heterogeneous habitats. Although most mobile species – especially generalists – probably frequently encounter habitat heterogeneity, the impact of preference induction on individual behaviour and fitness in heterogeneous habitats is poorly understood. We analysed larval preference induction in wheat-adapted generalist red flour beetles (Tribolium castaneum) under three types of habitat heterogeneity. We first analysed the induction of larval preference for novel resources (other cereal flours) under temporal heterogeneity, exposing larvae to new resources during development. We found that larvae preferred a new resource if they experienced it recently, but that the magnitude of induction varied across resources. Interestingly, we also observed specific induction for a homogenous mix of wheat and a novel resource, with larvae preferring the mix over either pure resource. To analyse induction under spatial heterogeneity, we placed beetle eggs in one of two alternative resource patches and tested the preference of emerged larvae. Unexpectedly, hatching into a novel resource did not always induce preference. Finally, we found that induction of preference for new resources could be maladaptive for larval development. Together, our work demonstrates that experience-based plasticity of larval resource choice may strongly impact larval preference and fitness in heterogeneous habitats.


2014 ◽  
Vol 1010-1012 ◽  
pp. 121-125
Author(s):  
Wen Bin Li ◽  
Zhi Ming Mo ◽  
Xing Ting Chen ◽  
Chun Huang ◽  
Ming Feng Xu

To examine the impact of habitat heterogeneity on the bird communities, we investigated the structural differences of various bird communities occurring in heterogeneous habitats in the subtropical hilly areas of southern China. We used indicator Species Analysis (ISA) to test the association of specific bird species to particular habitats. We performed Two-way Cluster Analysis to find species patterning in response to habitat fragmentation. Our results demonstrated that heterogeneous habitats promoted bird diversity and human activities affected bird behavior. Indicator Species Analysis demonstrated that similar habitats had similar bird communities, while different habitats supported various bird indicator species. Although habitat diversity increased bird diversity of a region, it was unfavorable for the maintenance of specialized birds in the forests of the subtropical hilly area.



2014 ◽  
Vol 112 (8) ◽  
pp. 1373-1383 ◽  
Author(s):  
Susan I. Barr ◽  
Loretta DiFrancesco ◽  
Victor L. Fulgoni

Although breakfast is associated with more favourable nutrient intake profiles in children, limited data exist on the impact of breakfast on nutrient adequacy and the potential risk of excessive intakes. Accordingly, we assessed differences in nutrient intake and adequacy among breakfast non-consumers, consumers of breakfasts with ready-to-eat cereal (RTEC) and consumers of other types of breakfasts. We used cross-sectional data from 12 281 children and adolescents aged 4–18 years who took part in the nationally representative Canadian Community Health Survey, 2004. Mean nutrient intakes (obtained using a multiple-pass 24 h recall method) were compared among the breakfast groups using covariate-adjusted regression analysis. Usual nutrient intake distributions, generated using the National Cancer Institute method, were used to determine the prevalence of nutrient inadequacy or the potential risk of excessive intakes from food sources alone and from the combination of food plus supplements. Of these Canadian children, 10 % were breakfast non-consumers, 33 % were consumers of RTEC breakfasts and 57 % were consumers of other types of breakfasts. Non-consumption of breakfast increased with age (4–8 years: 2 %; 9–13 years: 9 %; 14–18 years: 18 %). Breakfast consumers had higher covariate-adjusted intakes of energy, many nutrients and fibre, and lower fat intakes. The prevalence of nutrient inadequacy for vitamin D, Ca, Fe and Mg (from food alone or from the combination of food plus supplements) was highest in breakfast non-consumers, intermediate in consumers of other types of breakfasts and lowest in consumers of RTEC breakfast. For vitamin A, P and Zn, breakfast non-consumers had a higher prevalence of nutrient inadequacy than both breakfast groups. The potential risk of excessive nutrient intakes was low in all groups. Efforts to encourage and maintain breakfast consumption in children and adolescents are warranted.



2021 ◽  
Author(s):  
◽  
Cielle Stephens

Ecological restoration often involves revegetation. I have investigated the impact of revegetation on the distribution, abundance and body condition of skinks on Stephens Island (Takapourewa). I tested the prediction that only one, Oligosoma infrapunctatum, of the four skink species (Oligosoma lineoocellatum, O. nigriplantare polychroma, O. infrapunctatum andO. zelandicum) will benefit in terms of abundance and distribution from revegetation. Stephens Island is a Wildlife Sanctuary in the north-western Marlborough Sounds, New Zealand. The island is known for its diverse and abundant reptile community. Prior to the mid 19th century Stephens Island was covered in forest. Nearly 80% of this forest was destroyed following the establishment of a lighthouse and farm on the island in 1894. In 1989, when the control of Stephens Island passed to the Department of Conservation, reforestation became a key conservation goal. Stephens Island is currently a mosaic of different habitat types from pasture to coastal forest. Pitfall traps caught skinks for a mark-recapture study in four replicated habitat types: forest, tussock, pasture and replanted.<br><br>Oligosoma lineoocellatum comprised 75% of all individuals caught. Densities of O. lineoocellatum were higher in replanted habitat (3020/ha in December and 3770/ha in March) than tussock (2690/ha in December and 2560/ha in March) and lowest in the pasture (1740/hain December and 1960/ha in March). Rates of captures were too low to perform density estimates for the other three species. Trap occupancy rates indicate O. nigriplantare polychroma is more common in the tussock habitat, and O. infrapunctatum is more common in the replanted habitat. Few O. zelandicum were found, primarily in the tussock habitat. Pasture areas replanted 13 years ago (now scrub habitat) support a higher diversity and abundance of skinks. Forest areas remain depauperate of skinks. Skink preference for replanted areas suggests that, for now, revegetation benefits their populations, possibly due to greater food sources, lower predation pressure and a wider thermal range.<br><br>Body condition (log weight/ log snout-vent length) and proportion of tail loss of skinks were similar in the different habitat types. However, both O. nigriplantare polychroma and O.lineoocellatum had higher body condition in the replanted than the tussock habitat. Juvenile skinks had significantly lower body condition and a lower proportion of tail loss. Skink body condition was not negatively affected by revegetation or by different habitats, despite the large differences between the habitats. Revegetation currently benefits skink populations. Maintaining a mosaic of habitat types is recommended, because, should revegetation create more forest habitat through plantations or plant succession, it is likely that the population of all four species of skink will decline.<br>



Author(s):  
Michael A Robidoux ◽  
Derek Winnepetonga ◽  
Sylvia Santosa ◽  
François Haman

The food security crisis and disproportionately high burden of dietary related disease amongst northern Indigenous populations in Canada continues to be a troubling reality with little sign of improvement. The Government of Canada is responding by developing programs to support local food initiatives for northern isolated communities. While such investments appear commendable, the impact of local food harvesting to improve food security has yet to be determined. While there are clear nutritional and cultural benefits to traditional food sources, communities face considerable barriers acquiring it in sufficient amounts because of historically imposed lifestyle changes that have increased food insecurity rates. This study responds by providing a novel multidisciplinary approach that draws from firsthand experiences working with First Nations community members in a remote subarctic region in northwestern, Ontario to estimate their community’s total food requirement and the amount of wild animal food sources needed to sustain yearly food intake. This transferrable energy demand approach will be critical for policy makers to put into perspective the amount of wild food needed to have an impact on food security rates and ultimately improve dietary related diseases. Novelty: • It will provide government policy makers information about current harvest yields in a remote northern First Nation to understand the potential contribution of traditional food to improve local food security • Provides Indigenous communities a means to assess local food resources to measure the caloric contributions of traditional foods toward household food security



2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
A Varga ◽  
E Sarkadi Nagy ◽  
L Zámbó ◽  
É Illés ◽  
M Bakacs ◽  
...  

Abstract Trans fatty acids are formed during the industrial processing of food, and are proven to be harmful for the human body. They have been associated with increased risk of cardiovascular disease, abdominal obesity, diabetes, and certain types of cancer. Decree 71/2013. (XI. 20.) of the Ministry of Human Capacities, which has been in force since 2014, defines the highest permitted amount of trans fats in food products placed on the market in Hungary. The impact of the decree on the industrially produced trans fatty acids (iTFA) availability and population intake was assessed in 2017. Results demonstrated that iTFA were replaced by other fatty acids due to the legislation. In 2019, we investigated food groups which had high measured TFA content before the regulation entered into force and compared the total fat and fatty acid profiles to the same brand or similar products being on the market afterwards. In collaboration with the World Health Organization, this was the first assessment to determine to which extent manufacturers increased saturated fat (SFA) content of foodstuffs to reduce iTFA content. In those product groups, which were identified as significant food sources of iTFA before introducing the regulation (biscuits, coffee creamers and flavorings, sweets, bakery products, confectionary, wafers, margarines) we found no significant changes in the total fat content, while in most foodstuffs the average proportion of SFA was higher after reformulation, as iTFA were mainly substituted with SFA in 61% of the products, with cis-MUFA in 25% and cis-PUFA in 14% of the products, respectively. Evidence from this analysis supports concerns that eliminating iTFA in certain foodstuffs leads to unwanted substitution with saturated fat, hence reducing the possible health benefits. Given the high SFA intake and the unfavourable cardiovascular statistics in Hungary, the consumption frequency and portion size control of these products are advised. Key messages Monitoring the changes of food composition is important in order to evaluate the effect of the regulation. Manufacturers should be encouraged to reduce the SFA content to a technologically feasible level.



Author(s):  
Jorge Marques Pinto ◽  
Viviane Merzbach ◽  
Ashley G. B. Willmott ◽  
Jose Antonio ◽  
Justin Roberts

Abstract Background Prevalence of vitamin D insufficiency/deficiency has been noted in athletic populations, although less is known about recreationally active individuals. Biofortification of natural food sources (e.g. UV radiated mushrooms) may support vitamin D status and is therefore of current scientific and commercial interest. The aim of this study was to assess the impact of a mushroom-derived food ingredient on vitamin D status in recreationally active, healthy volunteers. Methods Twenty-eight participants were randomly assigned to either: 25 μg (1000 IU) encapsulated natural mushroom-derived vitamin D2; matched-dose encapsulated vitamin D3 or placebo (PL) for 12 weeks. Venous blood samples were collected at baseline, week 6 and 12 for analysis of serum 25(OH)D2 and 25(OH)D3 using liquid chromatography mass spectrometry. Habitual dietary intake and activity were monitored across the intervention. Results Vitamin D status (25(OH)DTOTAL) was significantly increased with vitamin D3 supplementation from 46.1 ± 5.3 nmol·L− 1 to 88.0 ± 8.6 nmol·L− 1 (p < 0.0001) across the intervention, coupled with an expected rise in 25(OH)D3 concentrations from 38.8 ± 5.2 nmol·L− 1 to 82.0 ± 7.9 nmol·L− 1 (p < 0.0001). In contrast, D2 supplementation increased 25(OH)D2 by + 347% (7.0 ± 1.1 nmol·L− 1 to 31.4 ± 2.1 nmol·L− 1, p < 0.0001), but resulted in a − 42% reduction in 25(OH)D3 by week 6 (p = 0.001). A net + 14% increase in 25(OH)DTOTAL was established with D2 supplementation by week 12 (p > 0.05), which was not statistically different to D3. Vitamin D status was maintained with PL, following an initial − 15% reduction by week 6 (p ≤ 0.046 compared to both supplement groups). Conclusions The use of a UV radiated mushroom food ingredient was effective in maintaining 25(OH)DTOTAL in healthy, recreationally active volunteers. This may offer an adjunct strategy in supporting vitamin D intake. However, consistent with the literature, the use of vitamin D3 supplementation likely offers benefits when acute elevation in vitamin D status is warranted.



BioScience ◽  
2019 ◽  
Vol 69 (11) ◽  
pp. 867-876 ◽  
Author(s):  
Michaela Schratzberger ◽  
Martijn Holterman ◽  
Dick van Oevelen ◽  
Johannes Helder

Abstract Free-living nematodes, an ancient animal phylum of unsegmented microscopic roundworms, have successfully adapted to nearly every ecosystem on Earth: from marine and freshwater to land, from the polar regions to the tropics, and from the mountains to the ocean depths. They are globally the most abundant animals in sediments and soils. In the present article, we identify the factors that collectively explain the successful ecological proliferation of free-living nematodes and demonstrate the impact they have on vital sediment and soil processes. The ecological success of nematodes is strongly linked to their ability to feed on various food sources that are present in both sediments and soils, and to proliferate rapidly and survive in contrasting environmental conditions. The adaptations, roles, and behaviors of free-living nematodes have important implications for the resilience of sediments and soils, and for emergent animal communities responding to human alterations to ecosystems worldwide.



1998 ◽  
Vol 33 (3) ◽  
pp. 282-391
Author(s):  
John D. Sedlacek ◽  
Robert J. Barney ◽  
Paul A. Weston ◽  
Bryan D. Price

The impact of malathion treatment and duration of storage prior to treatment on species composition and relative abundance of beetle pests was investigated in shelled corn in newly-constructed galvanized steel bins. Corn was sampled monthly for insects with plastic probe traps from January through September 1989. Red and confused flour beetles, Tribolium spp., hairy fungus beetle, Typhaea stercorea (L.), flat and rusty grain and flour mill beetles, Cryptolestes spp., and foreign grain beetle, Ahasverus advena (Waltl), were most abundant in traps, but plaster beetle, Cartodere constricta (Gyllenhal), minute brown fungus beetle, Corticaria pubescens (Gyllenhal), antlike flower beetle, Anthicus spp., and larger black flour beetle, Cynaeus angustus (LeConte), also were trapped. Greater numbers of the four major beetle species were trapped in older corn and in corn that was not treated with malathion and, depending on species, trap catch peaked in August or September. Information gathered during this investigation adds to our knowledge of insect infestation and insecticide application to on-farm stored corn and confirmed earlier reports that T. stercorea and A. advena potentially are pests of stored shelled corn. Thorough inspection and sampling should be conducted throughout the storage period, but especially after grain temperatures warm above 20°C.



1978 ◽  
Vol 35 (12) ◽  
pp. 1572-1579 ◽  
Author(s):  
Mark D. Morgan ◽  
Stephen T. Threlkeld ◽  
Charles R. Goldman

Introductions of opossum shrimp (Mysis relicta) and kokanee salmon (Oncorhynchus nerka) are common management tools for improvement of local sport fisheries. This paper summarizes published information from varied sources and presents supplemental data on the impact of these introductions on the Lake Tahoe zooplankton and fish communities. Concomitant with peak spawning runs of kokanee and the establishment and high densities of Mysis was the disappearance of the three pelagic cladoceran species in the lake. Population dynamics analysis of the cladoceran populations indicate that their elimination was due to increasing death rates (related to Mysis and kokanee predation) and decreasing birth rates (possibly related to cultural eutrophication). Changes have also been observed in the fish populations. Lake trout have altered their food habits to include large quantities of Mysis, but this has been done to the exclusion of other prey types. Thus, improvement in lake trout condition has been indicated only in years when Mysis is abundant. Recent evidence of a sustained decline in the mysid population suggests that unless lake trout shift back to more traditional food sources, their condition could deteriorate to below pre-mysid levels. Finally, mean weight and abundance of kokanee spawners have declined since the cladoceran disappearance, suggesting a negative impact on the whole population which fed heavily on cladocerans. Key words: opossum shrimp, kokanee salmon, population dynamics, cladoceran decline, introductions, subalpine lake



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