scholarly journals Consequences of consumer origin and omnivory on stability in experimental food web modules

2019 ◽  
Author(s):  
Monica Granados ◽  
Katie S. Pagnucco ◽  
Anthony Ricciardi
Keyword(s):  
Food Web ◽  
Coefficient Of Variation ◽  
Species Interactions ◽  
Native Species ◽  
Weak Interactions ◽  
Temporal Stability ◽  
List Type ◽  
Species Identity ◽  
Novel Ecosystem ◽  
Native Populations

AbstractFood web stability, a fundamental characteristic of ecosystems, is influenced by the nature and strength of species interactions. Theory posits that food webs are stabilized by omnivory and disrupted by novel consumers.To test the effects of secondary consumer origin and trophic level on basal resource stability, we constructed crayfish-snail-algae modules using four congeneric species of crayfish (Faxonius spp.), two from native populations (F. propinquus and F. virilis) and two from non-native populations (F. limosus and F. rusticus). We performed surgical manipulations of crayfish feeding structures to create omnivore food web and predator food chain modules. We compared the temporal stability of these modules using measures of the coefficient of variation of the basal resource (benthic algae).Consistent with theoretical and empirical predictions, food web modules with omnivory had the lowest coefficient of variation. However, contrary to prediction, we did not find consistently higher coefficients of variation in modules with non-native species. Rather, across species, we found the lowest coefficient of variation in modules with one of the non-native species (F. rusticus) and one native species (F. virilis), owing to stronger interactions between these crayfish species and their snail and algal food resources.The results suggest that omnivory is indeed stabilizing and that very weak interactions or very low attack rates of the consumer on the basal resource can be unstable. Thus, we demonstrate that omnivores may have different impacts than predators when introduced into a novel ecosystem, differences that can supersede the effect of species identity.

scholarly journals Genetic identity and genotype × genotype interactions between symbionts outweigh species level effects in an insect microbiome

2021 ◽  
Author(s):  
Melanie R. Smee ◽  
Sally A. Raines ◽  
Julia Ferrari
Keyword(s):  
Species Interactions ◽  
Acyrthosiphon Pisum ◽  
Parasitoid Wasp ◽  
Extensive Study ◽  
Genetic Identity ◽  
Host Genotype ◽  
Species Identity ◽  
Microbial Symbionts ◽  
And Performance ◽  
Multiple Species

AbstractMicrobial symbionts often alter the phenotype of their host. Benefits and costs to hosts depend on many factors, including host genotype, symbiont species and genotype, and environmental conditions. Here, we present a study demonstrating genotype-by-genotype (G×G) interactions between multiple species of endosymbionts harboured by an insect, and the first to quantify the relative importance of G×G interactions compared with species interactions in such systems. In the most extensive study to date, we microinjected all possible combinations of five Hamiltonella defensa and five Fukatsuia symbiotica (X-type; PAXS) isolates into the pea aphid, Acyrthosiphon pisum. We applied several ecological challenges: a parasitoid wasp, a fungal pathogen, heat shock, and performance on different host plants. Surprisingly, genetic identity and genotype × genotype interactions explained far more of the phenotypic variation (on average 22% and 31% respectively) than species identity or species interactions (on average 12% and 0.4%, respectively). We determined the costs and benefits associated with co-infection, and how these compared to corresponding single infections. All phenotypes were highly reliant on individual isolates or interactions between isolates of the co-infecting partners. Our findings highlight the importance of exploring the eco-evolutionary consequences of these highly specific interactions in communities of co-inherited species.

Galapagos Tortoises and Sea Turtles in Gold Rush-Era California

2014 ◽  
Vol 91 (2) ◽  
pp. 20-39 ◽  
Author(s):  
Cyler Conrad ◽  
Allen Pastron
Keyword(s):  
San Francisco ◽  
Native Species ◽  
Sea Turtles ◽  
Rare Event ◽  
Legal Protection ◽  
Sea Turtle ◽  
Gold Rush ◽  
Late Nineteenth Century ◽  
Scientific Curiosity ◽  
Native Populations

Spotting a sea turtle or Galapagos tortoise on the early wharfs and streets of San Francisco or Sacramento, California during the Gold Rush (1848-1855) would not have been a rare event. Massive population influx into the San Francisco Bay region during this time resulted in substantial impacts to native species and habitats of all taxa, but the demand for food resulted in many resources, turtles and tortoises included, being imported into the cities. Providing a fresh and delectable food source, these terrapin were brought to San Francisco and Sacramento to feed the hungry Gold Rush populous. Their taste, popularity and demand also resulted in small numbers being imported into gold mining towns in the San Joaquin Valley and foothills of the Sierra Nevada’s. Remarkable as this process was, the consumption and importation of both sea turtles and Galapagos tortoises during the Gold Rush pushed native populations of these species to the brink of extinction during the mid to late-nineteenth century. Declining numbers of terrapin and increased scientific curiosity, with a desire to safeguard these creatures for future generations, resulted in their eventually legal protection and conservation. In many ways the impacts of the decimation of terrapin in the eastern Pacific during the Gold Rush are still felt today, as conservation and breeding efforts continue in an attempt to return native turtle and tortoise populations to pre-Euro-American contact levels. This research describes the historical, and new archaeofaunal, evidence of the terrapin import market in San Francisco, Sacramento and beyond during the dynamic period of the California Gold Rush.

scholarly journals The influence of fish cage culture on δ13C and δ15N of filter-feeding Bivalvia (Mollusca)

2013 ◽  
Vol 73 (4) ◽  
pp. 743-746
Author(s):  
E. Benedito ◽  
L. Figueroa ◽  
A.M Takeda ◽  
GI. Manetta
Keyword(s):  
Food Web ◽  
Native Species ◽  
Corbicula Fluminea ◽  
Cage Culture ◽  
Aquatic Food Web ◽  
Δ13c And Δ15n ◽  
Value Analysis ◽  
Fine Powders ◽  
Before And After ◽  
Aquatic Food

The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ13C and δ15N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filterer C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ13C) and nitrogen (δ15N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ13C and δ15N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ13C and δ15N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem.

scholarly journals Food-web modification in the eastern Gulf of Finland after invasion of Marenzelleria arctia (Spionidae, Polychaeta)

NeoBiota ◽  
2021 ◽  
Vol 66 ◽  
pp. 75-94
Author(s):  
Sergey Golubkov ◽  
Alexei Tiunov ◽  
Mikhail Golubkov
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Food Chain ◽  
Native Species ◽  
Isotope Analysis ◽  
Marine Species ◽  
Trophic Levels ◽  
Benthivorous Fish ◽  
Neva Estuary ◽  
The Baltic

The paucity of data on non-indigenous marine species is a particular challenge for understanding the ecology of invasions and prioritising conservation and research efforts in marine ecosystems. Marenzelleria spp. are amongst the most successful non-native benthic species in the Baltic Sea during recent decades. We used stable isotope analysis (SIA) to test the hypothesis that the dominance of polychaete worm Marenzelleria arctia in the zoobenthos of the Neva Estuary after its invasion in the late 2000s is related to the position of this species in the benthic food webs. The trend towards a gradual decrease in the biomass of Marenzelleria worms was observed during 2014–2020, probably due to significant negative relationships between the biomass of oligochaetes and polychaetes, both of which, according to SIA, primarily use allochthonous organic carbon for their production. The biomass of benthic crustaceans practically did not change and remained very low. The SIA showed that, in contrast to the native crustacean Monoporeia affinis, polychates are practically not consumed either by the main invertebrate predator Saduria entomon, which preys on M. affinis, oligochaetes and larvae of chironomids or by benthivorous fish that prefer native benthic crustaceans. A hypothetical model for the position and functional role of M. arctia in the bottom food web is presented and discussed. According the model, the invasion of M. arctia has created an offshoot food chain in the Estuary food webs. The former dominant food webs, associated with native crustaceans, are now poorly developed. The lack of top-down control obviously contributes to the significant development of the Marenzelleria food chain, which, unlike native food chains, does not provide energy transfer from autochthonous and allochthonous organic matter to the upper trophic levels. The study showed that an alien species, without displacing native species, can significantly change the structure of food webs, creating blind offshoots of the food chain.

scholarly journals Genotype-Species Interactions in Neighbourhoods of Forest Tree Communities

2007 ◽  
Vol 56 (1-6) ◽  
pp. 101-110 ◽  
Author(s):  
Chr. Wehenkel ◽  
F. Bergmann ◽  
H.-R. Gregorius
Keyword(s):  
Species Interactions ◽  
Species Coexistence ◽  
Biotic Interactions ◽  
Forest Tree ◽  
Target Species ◽  
Species Identity ◽  
Enzymatic Function ◽  
Genotype Frequencies ◽  
Tree Communities ◽  
Large Survey

Abstract Studies on plant communities of various annual species suggest that there are particular biotic interactions among individuals from different species which could be the basis for long-term species coexistence. In the course of a large survey on species-genetic diversity relationships in several forest tree communities, it was found that statistically significant differences exist among isozyme genotype frequencies of conspecific tree groups, which differ only by species identity of their neighbours. Based on a specific measure, the association of the neighbouring species with the genotypes of the target species or that of the genotypes with the neighbouring species was quantified. Since only AAT and HEK of the five analysed enzyme systems differed in their genotype frequencies among several tree groups of the same target species, a potential involvement of their enzymatic function in the observed differences was discussed. The results of this study demonstrate a fine-scale genetic differentiation within single tree species of forest communities, which may be the result of biotic interactions between the genetic structure of a species and the species composition of its community. This observation also suggests the importance of intraspecific genetic variation for interspecific adaptation.

scholarly journals Competitive Replacement of Invasive Congeners May Relax Impact on Native Species: Interactions among Zebra, Quagga, and Native Unionid Mussels

PLoS ONE ◽  
2014 ◽  
Vol 9 (12) ◽  
pp. e114926 ◽  
Author(s):  
Lyubov E. Burlakova ◽  
Brianne L. Tulumello ◽  
Alexander Y. Karatayev ◽  
Robert A. Krebs ◽  
Donald W. Schloesser ◽  
...  
Keyword(s):  
Species Interactions ◽  
Native Species ◽  
Unionid Mussels

scholarly journals An ecosystem model of food web and fisheries interactions in the Baltic Sea

2003 ◽  
Vol 60 (5) ◽  
pp. 939-950 ◽  
Author(s):  
Chris J Harvey ◽  
Sean P Cox ◽  
Timothy E Essington ◽  
Sture Hansson ◽  
James F Kitchell
Keyword(s):  
Baltic Sea ◽  
Food Web ◽  
Species Interactions ◽  
Gadus Morhua ◽  
Population Analysis ◽  
Clupea Harengus ◽  
Trophic Relationships ◽  
The Baltic Sea ◽  
Management Actions ◽  
The Baltic

Abstract Because fisheries operate within a complex array of species interactions, scientists increasingly recommend multispecies approaches to fisheries management. We created a food web model for the Baltic Sea proper, using the Ecopath with Ecosim software, to evaluate interactions between fisheries and the food web from 1974 to 2000. The model was based largely on values generated by multispecies virtual population analysis (MSVPA). Ecosim outputs closely reproduced MSVPA biomass estimates and catch data for sprat (Sprattus sprattus), herring (Clupea harengus), and cod (Gadus morhua), but only after making adjustments to cod recruitment, to vulnerability to predation of specific species, and to foraging times. Among the necessary adjustments were divergent trophic relationships between cod and clupeids: cod exhibited top-down control on sprat biomass, but had little influence on herring. Fishing, the chief source of mortality for cod and herring, and cod reproduction, as driven by oceanographic conditions as well as unexplained variability, were also key structuring forces. The model generated many hypotheses about relationships between key biota in the Baltic Sea food web and may ultimately provide a basis for estimating community responses to management actions.

Multiple feedbacks due to biotic interactions across trophic levels can lead to persistent novel conditions that hinder restoration.

2020 ◽  
pp. 402-420
Author(s):  
Stephanie G. Yelenik ◽  
Carla M. D'Antonio ◽  
Evan M. Rehm ◽  
Iain R. Caldwell
Keyword(s):  
Species Interactions ◽  
Native Species ◽  
Biotic Interactions ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Native Grasses ◽  
Positive Feedbacks ◽  
Mesic Forest ◽  
Management Context ◽  
Multiple Challenges

Abstract Unlike traditional successional theory, Alternate Stable Equilibrium (ASE) theory posits that more than one community state is possible in a single environment, depending on the order that species arrive. ASE theory is often invoked in management situations where initial stressors have been removed, but native-dominated communities are not returning to degraded areas. Fundamental to this theory is the assumption that equilibria are maintained by positive feedbacks between colonizers and their environment. While ASE has been relatively well studied in aquatic ecosystems, more complex terrestrial systems offer multiple challenges, including species interactions across trophic levels that can lead to multiple feedbacks. Here, we discuss ASE theory as it applies to terrestrial, invaded ecosystems, and detail a case study from Hawai'i that exemplifies how species interactions can favour the persistence of invaders, and how an understanding of interactions and feedbacks can be used to guide management. Our system includes intact native-dominated mesic forest and areas cleared for pasture, planted with non-native grasses, and later planted with a monoculture of a native nitrogen-fixing tree in an effort to restore forests. We discuss interactions between birds, understorey fruiting native species, understorey non-native grasses, soils and bryophytes in separate feedback mechanisms, and explain our efforts to identify which of these feedbacks is most important to address in a management context. Finally, we suggest that using models can help overcome some of the challenges that terrestrial ecosystems pose when studying ASE.

How a network approach has advanced the field of plant invasion ecology.

2020 ◽  
pp. 324-339
Author(s):  
Carine Emer ◽  
◽  
Sérgio Timóteo ◽  
◽  
Keyword(s):  
Species Interactions ◽  
Plant Invasion ◽  
Native Species ◽  
Invasion Biology ◽  
Plant Invasions ◽  
Network Approach ◽  
Native Plant Species ◽  
Functional Roles ◽  
Network Approaches ◽  
Plant Herbivore

Every organism on Earth, whether in natural or anthropogenic environments, is connected to a complex web of life, the famous 'entangled bank' coined by Darwin in 1859. Non-native species can integrate into local 'banks' by establishing novel associations with the resident species. In that context, network ecology has been an important tool to study the interactions of non-native species and the effects on recipient communities due to its ability to simultaneously investigate the assembly and disassembly of species interactions as well as their functional roles. Its visually appealing tools and relatively simple metrics gained momentum among scientists and are increasingly applied in different areas of ecology, from the more theoretical grounds to applied research on restoration and conservation. A network approach helps us to understand how plant invasions may or may not form novel species associations, how they change the structure of invaded communities, the outcomes for ecosystem functionality and, ultimately, the implications for the conservation of ecological interactions. Networks have been widely used on pollination studies, especially from temperate zones, unveiling their nested patterns and the mechanisms by which non-native plants integrate into local communities. Yet, very few papers have used network approaches to assess plant invasion effects in other systems such as plant-herbivore, plant-pathogen or seed-dispersal processes. Here we describe how joining network ecology with plant invasion biology started and how it has developed over the last few decades. We show the extent of its contribution, despite contradictory results and biases, to a better understanding of the role of non-native plant species in shaping community structure. Finally, we explore how it can be further improved to answer emerging questions.

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