scholarly journals Grazing by large savanna herbivores indirectly alters ant diversity and promotes resource monopolisation

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6226 ◽  
Author(s):  
Jean Purdon ◽  
Catherine L. Parr ◽  
Michael J. Somers
Keyword(s):  
Body Size ◽  
Habitat Complexity ◽  
Habitat Structure ◽  
Foraging Behaviour ◽  
Layer Structure ◽  
Structural Complexity ◽  
Structure And Function ◽  
Bunch Grass ◽  
And Function ◽  
Ant Diversity

In savannas, grazing is an important disturbance that modifies the grass layer structure and composition. Habitat structural complexity influences species diversity and assemblage functioning. By using a combination of natural sites and manipulated experiments, we explored how habitat structure (grazing lawns and adjacent bunch grass) affects ant diversity and foraging behaviour, specifically the efficiency of resource acquisition, resource monopolisation and ant body size. We found that in the natural sites there was no difference in the amount of time ants took to locate resources, but in the manipulated experiments, ants were faster at locating resources and were more abundant in the simple treatments than in the more complex treatments. Ant body size was only affected by the manipulated experiments, with smaller ants found in the more complex treatments. In both the grazing lawn and bunch grass habitats there were differences in assemblage patterns of ants discovering resources and those dominating them. Seasonality, which was predicted to affect the speed at which ants discovered resources and the intensity of resource monopolisation, also played a role. We show that ants in winter monopolised more baits and discovered resources at a slower rate, but only at certain times within the experiment. Grazing in conjunction with season thus had a significant effect on ant diversity and foraging behaviour, with dominant ants promoted where habitat complexity was simplified when temperatures were low. Our results indicate that structural complexity plays a major role in determining ant assemblage structure and function in African savannas.

scholarly journals Carbohydrate complexity structures stable diversity in gut-derived microbial consortia under high dilution pressure

2020 ◽  
Author(s):  
Tianming Yao ◽  
Ming-Hsu Chen ◽  
Stephen R. Lindemann
Keyword(s):  
Microbial Diversity ◽  
Structural Complexity ◽  
Structure And Function ◽  
Microbial Consortia ◽  
Carbohydrate Structure ◽  
High Dilution ◽  
Chemical Complexity ◽  
Metabolic Interactions ◽  
And Function

ABSTRACTDietary fibers are major substrates for the colonic microbiota, but the structural specificity of these fibers for the diversity, structure, and function of gut microbial communities are poorly understood. Here, we employed an in vitro sequential batch fecal culture approach to determine: 1) whether the chemical complexity of a carbohydrate structure influences its ability to maintain microbial diversity in the face of high dilution pressure and 2) whether substrate structuring or obligate microbe-microbe metabolic interactions (e.g. exchange of amino acids or vitamins) exert more influence on maintained diversity. Sorghum arabinoxylan (SAX, complex polysaccharide), inulin (low-complexity oligosaccharide) and their corresponding monosaccharide controls were selected as model carbohydrates. Our results demonstrate that complex carbohydrates stably sustain diverse microbial consortia. Further, very similar final consortia were enriched on SAX from the same individual’s fecal microbiota across a one-month interval, suggesting that polysaccharide structure is more influential than stochastic alterations in microbiome composition in governing the outcomes of sequential batch cultivation experiments. SAX-consuming consortia were anchored by Bacteroides ovatus and retained diverse consortia of >12 OTUs; whereas final inulin-consuming consortia were dominated either by Klebsiella pneumoniae or Bifidobacterium sp. and Escherichia coli. Furthermore, auxotrophic interactions were less influential in structuring microbial consortia consuming SAX than the less-complex inulin. These data suggest that carbohydrate structural complexity affords independent niches that structure fermenting microbial consortia, whereas other metabolic interactions govern the composition of communities fermenting simpler carbohydrates.IMPORTANCEThe mechanisms by which gut microorganisms compete for and cooperate on human-indigestible carbohydrates of varying structural complexity remain unclear. Gaps in this understanding make it challenging to predict the effect of a particular dietary fiber’s structure on the diversity, composition, or function of gut microbiomes, especially with inter-individual variability in diets and microbiomes. Here, we demonstrate that carbohydrate structure governs the diversity of gut microbiota under high dilution pressure, suggesting that such structures may support microbial diversity in vivo. Further, we also demonstrate that carbohydrate polymers are not equivalent in the strength by which they influence community structure and function, and that metabolic interactions among members arising due to auxotrophy exert significant influence on the outcomes of these competitions for simpler polymers. Collectively, these data suggest that large, complex dietary fiber polysaccharides structure the human gut ecosystem in ways that smaller and simpler ones may not.

scholarly journals STRUCTURAL COMPLEXITY OF ARTIFICIAL HABITAT AND THE FEEDING SUCCESS OF PREDATORY DRAGONFLY AND DAMSELFLY

2013 ◽  
Vol 13 (2) ◽  
Author(s):  
Khairuddin, Lalu Japa Dan Nur Lestari
Keyword(s):  
Habitat Complexity ◽  
Habitat Structure ◽  
Simple Structure ◽  
Complex Structure ◽  
Structural Complexity ◽  
Artificial Habitat ◽  
Artificial Habitats ◽  
Feeding Success ◽  
Structure Complexity

AbstractThe effect of different habitat complexity structure on the feeding success of predatoryDragonfly and Damselfly over the four of three hours trials was tested using an artificialhabitat complexity structure. Complexity of artificial habitat structure was performed usingwoody bamboo stick of 5 cm in length and 2 mm in diameter. The artificial habitats were setin plastic tank with length and wide of 17 cm and 11.5 cm, respectively and 5.5 cm high. Thedeep of water colom was about 4.5 cm. Preys were larvae of mosquitoes. There was highlysignificant of feeding success of predators in simple structure of habitats and significantenough in complex structure of habitats. In other words, feeding success of predatoryDragonfly and Damselfly was much higher in the simple habitats structure compared to thatof the complex one.Key Words : Artificial Habitat, Damselfly, Dragonfly, Feeding, and PredatoryAbstrakPengaruh kompleksitas struktur habitat terhadap keberhasilan pemangsaan predator Dragonflydan Damselfly selama empat kali tiga jam perlakuan diteliti di laboratorium menggunakanhabitat buatan. Kompleksitas struktur habitat dibuat dengan tongkat dari bambu berukuranpanjang 5 cm dengan diameter 2 mm. Habitat buatan dibuat di bak plastik berukuran panjangdan lebar masing-masing 17 cm dan 11,5 cm, dan tinggi 5,5 cm dengan kedalaman kolom airsekitar 4,5 cm. Larva nyamuk digunakan sebagai pangsa dalam penelitian ini. Setiapperlakuan terdiri dari dua ulangan. Setiap perlakuan berlangsung empat kali masing-masingselama tiga jam. Hasil memperlihatkan, keberhasilan pemangsaan Dragonfly dan Damselflysangat signifikan pada habitat stuktur sederhana, dan cukup signifikan pada habitat yangkompleks. Dengan kata lain, keberhasilan pemangsaan Dragonfly dan Damselfly jauh lebihtinggi pada habitat berstruktur sederhana dibanding dengan pada habitat berstrukturkompleks.Kata Kunci : Damselfly, Draggonfly, Habitat Buatan, Pemangsaan, Pemangsa (Predator)

Advances in understanding the physiology, behaviour, and ecology of sea otters

2018 ◽  
Author(s):  
James A. Estes ◽  
M. Tim Tinker ◽  
Terrie M. Williams
Keyword(s):  
Marine Mammal ◽  
Life Histories ◽  
Foraging Behaviour ◽  
Post Partum ◽  
Structure And Function ◽  
Sea Otter ◽  
Sea Otters ◽  
Coastal Marine ◽  
Coastal Marine Ecosystems ◽  
And Function

Sea otters are the only fully marine-living mustelid and the smallest extant marine mammal. They have the highest mass-specific metabolic rate of any marine mammal, which coupled with the lack of blubber for insulator and energy storage, relegates them to operating as an extreme income strategist, and appears to have led to a life history tactic in which pregnancy rate is fixed while reproductive success varies with the mother’s body condition at the time of birth, which triggers a decision immediately post-partum to care for or abandon her pup. When resources are limiting, sea otters assume highly individualized diets, which are inherited matrilineally. Sea otters exert strong limiting influences on their macroinvertebrate prey, leading to far reaching indirect effects on the structure and function of coastal marine ecosystems. This chapter reviews and synthesizes the interplay between sea otter energetics and life histories, diet and foraging behaviour, and ecosystem influences.

Bowman's Layer Structure and Function

Cornea ◽  
2000 ◽  
Vol 19 (4) ◽  
pp. 417-420 ◽  
Author(s):  
Steven E. Wilson ◽  
Jong-Wook Hong
Keyword(s):  
Layer Structure ◽  
Structure And Function ◽  
And Function

scholarly journals Exploitative Competition and Risk of Parasitism in Two Host Ant Species: The Roles of Habitat Complexity, Body Size, and Behavioral Dominance

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Elliot B. Wilkinson ◽  
Donald H. Feener
Keyword(s):  
Body Size ◽  
Habitat Complexity ◽  
Structural Complexity ◽  
Resource Discovery ◽  
Relative Importance ◽  
Exploitative Competition ◽  
Specific Manner ◽  
Species Specific ◽  
Host Body Size

Habitat structural complexity can slow resource discovery by ants but can also lower the risk of parasitism during foraging. The relative importance of these two ecological facets of habitat complexity may differ in a species-specific manner and thus may be important in the outcome of exploitative competition over food resources. For the host ant speciesPheidole diversipilosaandP. bicarinata, we used in situ experimental manipulations to explore whether the effects of habitat complexity on exploitative competition depended on host body size and behavioral dominance, two characteristics likely to affect mobility and utilization of refuge from specialist Dipteran parasitoids (Apocephalus orthocladiusandA. pugilist, resp.). We found that habitat complexity affected the resource discovery and harvest components of exploitative competition in an opposing fashion for each species and discuss these results in light of the differences in body size and behavioral dominance between the two hosts.

scholarly journals Shade alters savanna grass layer structure and function along a gradient of canopy cover

2020 ◽  
Author(s):  
Natashi A. L. Pilon ◽  
Giselda Durigan ◽  
Jess Rickenback ◽  
R. Toby Pennington ◽  
Kyle G. Dexter ◽  
...  
Keyword(s):  
Layer Structure ◽  
Canopy Cover ◽  
Structure And Function ◽  
And Function

scholarly journals Effects of land abandonment and changing habitat structure on avian assemblages in upland pastures of Bulgaria

2009 ◽  
Vol 20 (2) ◽  
pp. 200-213 ◽  
Author(s):  
STOYAN C. NIKOLOV
Keyword(s):  
Habitat Complexity ◽  
Habitat Structure ◽  
Structural Characteristics ◽  
Conservation Status ◽  
Grassland Birds ◽  
Bird Species ◽  
Structural Complexity ◽  
Bird Community ◽  
Bird Species Richness ◽  
Point Count

SummaryOver the past half century, grassland birds in Europe have declined dramatically and in order to maintain and restore their populations it is critical to understand how habitat structures and quality within pastures affect birds. This study investigated the effects of habitat structure and pasture abandonment on grassland birds in IBA Ponor, western Bulgaria. Birds were sampled using the point count method at 143 randomly located circular plots and a total of 1,401 observations of birds from 31 species were recorded. The results showed that habitat complexity, management and landscape position influenced bird community structure and species occurrence within the upland pastures. Extensively grazed pastures supported higher structural complexity of vegetation cover and higher bird-species richness and diversity compared with abandoned ones. Moreover, bird species with a preference for grazed rather than abandoned pastures had higher conservation status and most were associated with shrub cover. To maintain high levels of avian diversity, habitat complexity within pastures should be maintained through extensive grazing, to ensure availability of scrub vegetation wherever possible. Finally, this study provided evidence that agri-environmental schemes should not be directly extrapolated from one country or region to another without been tested first, because within the same management, differences in habitat structural characteristics may exist due to the landscape and socio-economic characteristics of the region.

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