scholarly journals Parasite mediated competition facilitates invasion

2017 ◽  
Author(s):  
Senay Yitbarek ◽  
Ivette Perfecto ◽  
John H. Vandermeer
Keyword(s):  
Puerto Rico ◽  
Indirect Effects ◽  
Arrival Time ◽  
Trophic Levels ◽  
Competitive Interactions ◽  
Arboreal Ants ◽  
Wasmannia Auropunctata ◽  
Introduced Range ◽  
Phorid Flies ◽  
Phorid Fly

Parasites play an important role in invasion success with important consequences for biodiversity and community structure. While much research has focused on direct effects of parasites on biological invasions, parasites can also indirectly influence interactions within the invaded community across trophic levels. For instance, parasites can mediate competitive interactions between native and exotic species through trait-mediated indirect effects. We consider the interactions between the parasitoid fly Pseudacteon sp. (Diptera: Phoridae), and its native host ant Linipethema iniquum, and the exotic ant Wasmannia auropunctata in the introduced range of Puerto Rico. We examined the effects of phorid flies on the competitive outcome between the arboreal ants W. auropunctata and native ant L. iniquum. Furthermore, we investigate the searching efficiency of phorid flies in detecting L. iniquum nests. To study the indirect effects on ant competition, we monitored ant recruitment to baits over a 60-min time interval in the presence and absence of phorid fly parasitoids. We then performed field experiments and measured phorid arrival time to arboreal nests of L. iniquum located in both a) W. auropunctata patches and in b) isolated patches dominated by L. iniquum nests. We found that the presence of phorid fly significantly reduced recruitment of L. iniquum workers to baits through induced behavioral changes thereby increasing the ability of W. auropunctata to acquire resources. In addition, we found that phorid arrival time in isolated patches of L. iniquum patches was faster as compared to L. iniquum nests located within W. auropunctata patches. Our results show that phorid fly parasitoids indirectly may influence competitive interactions by attacking the host-ant L. iniquum and consequently providing an advantage to local spread of W. auropuntata populations in Puerto Rico. However, the spatial dynamics of arboreal ants shows that L. iniquum seeks protection from phorid fly parasotoids by moving their nests to W. auropunctata dominated patches.

Trophic Cascades in Grasslands

2018 ◽  
Author(s):  
Brian J. Wilsey
Keyword(s):  
Indirect Effects ◽  
Prey Species ◽  
Trophic Levels ◽  
Herbaceous Plant ◽  
Direct Effects ◽  
Temperate Grasslands ◽  
Cascading Effect ◽  
Top Predators ◽  
Invertebrate Predators ◽  
Ecology Of Fear

Top predators have effects that can ‘cascade down’ on lower trophic levels. Because of this cascading effect, it matters how many trophic levels are present. Predators are either ‘sit and wait’ or ‘active’. Wolves are top predators in temperate grasslands and can alter species composition of smaller-sized predators, prey, and woody and herbaceous plant species, either through direct effects or indirect effects (‘Ecology of Fear’). In human derived grasslands, invertebrate predators fill a similar ecological role as wolves. Migrating populations of herbivores tend to be more limited by food than non-migratory populations. The phenology and synchrony of births vary among prey species in a way that is consistent with an adaptation to predation. Precocious species have highly synchronous birth dates to satiate predators. Non-precocious species (‘hiders’) have asynchronous births. Results from studies that manipulate both predators and food support the hypothesis that bottom-up and top-down effects interact.

scholarly journals Crying wolf to a predator: deceptive vocal mimicry by a bird protecting young

2015 ◽  
Vol 282 (1809) ◽  
pp. 20150798 ◽  
Author(s):  
Branislav Igic ◽  
Jessica McLachlan ◽  
Inkeri Lehtinen ◽  
Robert D. Magrath
Keyword(s):  
Indirect Effects ◽  
Trophic Levels ◽  
Alarm Calls ◽  
Toxic Species ◽  
Vocal Mimicry ◽  
Primary Nest ◽  
Defence Strategy ◽  
Multiple Species ◽  
Defensive Mimicry ◽  
As If

Animals often mimic dangerous or toxic species to deter predators; however, mimicry of such species may not always be possible and mimicry of benign species seems unlikely to confer anti-predator benefits. We reveal a system in which a bird mimics the alarm calls of harmless species to fool a predator 40 times its size and protect its offspring against attack. Our experiments revealed that brown thornbills ( Acanthiza pusilla ) mimic a chorus of other species' aerial alarm calls, a cue of an Accipiter hawk in flight, when predators attack their nest. The absence of any flying predators in this context implies that these alarms convey deceptive information about the type of danger present. Experiments on the primary nest predators of thornbills, pied currawongs ( Strepera graculina ), revealed that the predators treat these alarms as if they themselves are threatened by flying hawks, either by scanning the sky for danger or fleeing, confirming a deceptive function. In turn, these distractions delay attack and provide thornbill nestlings with an opportunity to escape. This sophisticated defence strategy exploits the complex web of interactions among multiple species across several trophic levels, and in particular exploits a predator's ability to eavesdrop on and respond appropriately to heterospecific alarm calls. Our findings demonstrate that prey can fool predators by deceptively mimicking alarm calls of harmless species, suggesting that defensive mimicry could be more widespread because of indirect effects on predators within a web of eavesdropping.

scholarly journals Trait-mediated trophic cascade creates enemy-free space for nesting hummingbirds

2015 ◽  
Vol 1 (8) ◽  
pp. e1500310 ◽  
Author(s):  
Harold F. Greeney ◽  
M. Rocio Meneses ◽  
Chris E. Hamilton ◽  
Eli Lichter-Marck ◽  
R. William Mannan ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Fragmentation ◽  
Breeding Success ◽  
Indirect Effects ◽  
Trophic Cascade ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Ecological Communities ◽  
Top Predators ◽  
Enemy Free Space

The indirect effects of predators on nonadjacent trophic levels, mediated through traits of intervening species, are collectively known as trait-mediated trophic cascades. Although birds are important predators in terrestrial ecosystems, clear examples of trait-mediated indirect effects involving bird predators have almost never been documented. Such indirect effects are important for structuring ecological communities and are likely to be negatively impacted by habitat fragmentation, climate change, and other factors that reduce abundance of top predators. We demonstrate that hummingbirds in Arizona realize increased breeding success when nesting in association with hawks. An enemy-free nesting space is created when jays, an important source of mortality for hummingbird nests, alter their foraging behavior in the presence of their hawk predators.

Trophic cascades in benthic marine ecosystems: lessons for fisheries and protected-area management

2000 ◽  
Vol 27 (2) ◽  
pp. 179-200 ◽  
Author(s):  
J.K. PINNEGAR ◽  
N.V.C. POLUNIN ◽  
P. FRANCOUR ◽  
F. BADALAMENTI ◽  
R. CHEMELLO ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Large Scale ◽  
Trophic Cascades ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Kelp Forests ◽  
Resource Exploitation ◽  
Rocky Subtidal ◽  
Fishery Exploitation ◽  
Cascade Effects

An important principle of environmental science is that changes in single components of systems are likely to have consequences elsewhere in the same systems. In the sea, food web data are one of the few foundations for predicting such indirect effects, whether of fishery exploitation or following recovery in marine protected areas (MPAs). We review the available literature on one type of indirect interaction in benthic marine ecosystems, namely trophic cascades, which involve three or more trophic levels connected by predation. Because many indirect effects have been revealed through fishery exploitation, in some cases we include humans as trophic levels. Our purpose is to establish how widespread cascades might be, and infer how likely they are to affect the properties of communities following the implementation of MPAs or intensive resource exploitation. We review 39 documented cascades (eight of which include humans as a trophic level) from 21 locations around the world; all but two of the cascades are from shallow systems underlain by hard substrata (kelp forests, rocky subtidal, coral reefs and rocky intertidal). We argue that these systems are well represented because they are accessible and also amenable to the type of work that is necessary. Nineteen examples come from the central-eastern and north-eastern Pacific, while no well-substantiated benthic cascades have been reported from the NE, CE or SW Atlantic, the Southern Oceans, E Indian Ocean or NW Pacific. The absence of examples from those zones is probably due to lack of study. Sea urchins are very prominent in the subtidal examples, and gastropods, especially limpets, in the intertidal examples; we suggest that this may reflect their predation by fewer specialist predators than is the case with fishes, but also their conspicuousness to investigators. The variation in ecological resolution amongst studies, and in intensity of study amongst systems and regions, indicates that more cascades will likely be identified in due course. Broadening the concept of cascades to include pathogenic interactions would immediately increase the number of examples. The existing evidence is that cascade effects are to be expected when hard-substratum systems are subject to artisanal resource exploitation, but that the particular problems of macroalgal overgrowth on Caribbean reefs and the expansion of coralline barrens in the Mediterranean rocky-sublittoral will not be readily reversed in MPAs, probably because factors other than predation-based cascades have contributed to them in the first place. More cascade effects are likely to be found in the soft-substratum systems that are crucial to so many large-scale fisheries, when opportunities such as those of MPAs and fishing gradients become available for study of such systems, and the search is widened to less conspicuous focal organisms such as polychaetes and crustaceans.

Direct and indirect effects of near-future pCO2 levels on zooplankton dynamics

2017 ◽  
Vol 68 (2) ◽  
pp. 373 ◽  
Author(s):  
Cédric L. Meunier ◽  
María Algueró-Muñiz ◽  
Henriette G. Horn ◽  
Julia A. F. Lange ◽  
Maarten Boersma
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
Trophic Levels ◽  
Model Organisms ◽  
High Pco2 ◽  
Direct And Indirect Effects ◽  
Oxyrrhis Marina ◽  
Short Term Exposure ◽  
Zooplankton Growth ◽  
Seawater Pco2

Ocean acidification has direct physiological effects on organisms, for example by dissolving the calcium carbonate structures of calcifying species. However, non-calcifiers may also be affected by changes in seawater chemistry. To disentangle the direct and indirect effects of ocean acidification on zooplankton growth, we undertook a study with two model organisms. Specifically, we investigated the individual effects of short-term exposure to high and low seawater pCO2, and different phytoplankton qualities as a result of different CO2 incubations on the growth of a heterotrophic dinoflagellate (Oxyrrhis marina) and a copepod species (Acartia tonsa). It was observed previously that higher CO2 concentrations can decrease phytoplankton food quality in terms of carbon:nutrient ratios. We therefore expected both seawater pCO2 (pH) and phytoplankton quality to result in decreased zooplankton growth. Although we expected lowest growth rates for all zooplankton under high seawater pCO2 and low algal quality, we found that direct pH effects on consumers seem to be of lesser importance than the associated decrease in algal quality. The decrease in the quality of primary producers under high pCO2 conditions negatively affected zooplankton growth, which may lead to lower availability of food for the next trophic level and thus potentially affect the recruitment of higher trophic levels.

scholarly journals Meta-Analysis Suggests Differing Indirect Effects of Viral, Bacterial, and Fungal Plant Pathogens on the Natural Enemies of Insect Herbivores

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 765
Author(s):  
Ussawit Srisakrapikoop ◽  
Tara J. Pirie ◽  
Mark D. E. Fellowes
Keyword(s):  
Natural Enemies ◽  
Indirect Effects ◽  
Plant Pathogens ◽  
Meta Analysis ◽  
Trophic Levels ◽  
Plant Diseases ◽  
Plant Quality ◽  
Insect Herbivore ◽  
Insect Herbivores ◽  
Fungal Plant Pathogens

Indirect effects are ubiquitous in nature, and have received much attention in terrestrial plant–insect herbivore–enemy systems. In such tritrophic systems, changes in plant quality can have consequential effects on the behavior and abundance of insect predators and parasitoids. Plant quality as perceived by insect herbivores may vary for a range of reasons, including because of infection by plant pathogens. However, plant diseases vary in their origin (viral, bacterial or fungal) and as a result may have differing effects on plant physiology. To investigate if the main groups of plant pathogens differ in their indirect effects on higher trophic levels, we performed a meta-analysis using 216 measured responses from 29 primary studies. There was no overall effect of plant pathogens on natural enemy traits as differences between pathogen types masked their effects. Infection by fungal plant pathogens showed indirect negative effects on the performance and preference of natural enemies via both chewing and piercing-sucking insect herbivore feeding guilds. Infection by bacterial plant pathogens had a positive effect on the natural enemies (parasitoids) of chewing herbivores. Infection by viral plant pathogens showed no clear effect, although parasitoid preference may be positively affected by their presence. It is important to note that given the limited volume of studies to date on such systems, this work should be considered exploratory. Plant pathogens are very common in nature, and tritrophic systems provide an elegant means to examine the consequences of indirect interactions in ecology. We suggest that further studies examining how plant pathogens affect higher trophic levels would be of considerable value.

Natural Enemies of the Cacao Thrips

1943 ◽  
Vol 34 (4) ◽  
pp. 313-321 ◽  
Author(s):  
E. McC. Callan
Keyword(s):  
Puerto Rico ◽  
Natural Enemies ◽  
West Indies ◽  
Gold Coast ◽  
The West ◽  
Wasmannia Auropunctata ◽  
Economic Control ◽  
Population Counts

(1) Previous records of natural enemies of the cacao thrips, Selenothrips rubrocinctus, Giard, are reviewed.(2) An account is given of the following natural enemies in Trinidad, B.W.I. :—Dasyscapus parvipennis, Franklinothrips tenuicornis, F. vespiformis, Chrysopids, Ninyas torvus, Termatophylidea maculata and Wasmannia auropunctata.(3) The Eulophid parasite, Dasyscapus parvipennis, was introduced into the West Indies from the Gold Coast in 1935. It is now successfully established in Trinidad, Puerto Rico and Jamaica, but has so far given no indication of economic control of the cacao thrips.(4) The importance of natural enemies is discussed. Observations are made on the feeding propensities of some of the predators in the laboratory. Chrysopids are regarded as the most important predators and probably exercise some measure of control.(5) Population counts of the cacao thrips and Chrysopid and Franklinothrips larvae are given.

scholarly journals Current Understanding and Future Prospects of Host Selection, Acceptance, Discrimination, and Regulation of Phorid Fly Parasitoids That Attack Ants

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Kaitlyn A. Mathis ◽  
Stacy M. Philpott
Keyword(s):  
Current Understanding ◽  
Host Acceptance ◽  
Future Directions ◽  
Habitat Location ◽  
Host Habitat ◽  
Phorid Flies ◽  
Multiple Species ◽  
Host Habitat Location ◽  
Host Regulation ◽  
Phorid Fly

Phorid fly parasitoids (Diptera: Phoridae) have evolved a diverse array of cues used to successfully parasitize their ant hosts. Successful parasitism often involves (a) host habitat location, (b) host location, (c) host acceptance, (d) host discrimination, and (e) host regulation. In this paper we discuss our current understanding of how phorid flies use each of these steps to successfully parasitize ant hosts. We examine the wide variety of strategies and cues used by a multiple species of phorid flies within three separate genera that most commonly parasitize ants (Apocephalus,Pseudacteon,and Neodohrniphora) and discuss future directions within this field of study.

scholarly journals How Does Nutrient Availability Affect the Population Dynamics of the Invasive New Zealand Mud Snail (Potamopyrgus Antipodarum)?

2009 ◽  
Vol 32 ◽  
pp. 123-124
Author(s):  
Teresa Tibbets
Keyword(s):  
New Zealand ◽  
Population Growth ◽  
Invasion Biology ◽  
Potamopyrgus Antipodarum ◽  
Trophic Levels ◽  
Invasion Success ◽  
Population Growth Rates ◽  
Mud Snail ◽  
Introduced Range ◽  
New Zealand Mud Snail

A primary goal of invasion biology is to predict which introduced species become invasive and which systems are susceptible to invasion. Therefore it is vital to understand how invasive species sustain positive population growth rates in their introduced range and what environmental factors control population growth. The New Zealand mud snail (Potamopyrgus antipodarum) (Figure 1.) has spread throughout Europe, Australia, and North America, and has reached pest densities in many streams in the Greater Yellowstone Area (GYA) since their introduction in the 1980‘s. High rates of growth and secondary production have been documented for mud snails in its introduced range in the GYA, as have evidence of negative interactions between mud snails and native macroinvertebrates and higher trophic levels. However, little is known about how the availability of nutrients affects the invasion success of mud snails.

scholarly journals Competitive release from native range does not predict invasive success of a globally dominant exotic ant species

2017 ◽  
Author(s):  
Senay Yitbarek ◽  
Ivette Perfecto ◽  
John H. Vandermeer
Keyword(s):  
Puerto Rico ◽  
Exotic Species ◽  
Comparative Studies ◽  
Competitive Ability ◽  
Resource Competition ◽  
Invasion Success ◽  
Native Range ◽  
Short Term ◽  
Competitive Release ◽  
Introduced Range

AbstractA major goal of invasion biology is to understand under what conditions exotic species thrive in the introduced range. High competitive abilities are thought to be an important characteristic of exotic species. Most invasion studies focus on the competitive ability of exotic species in the introduced range and attribute their ecological success to competitive release, but fewer studies have compared the relative competitive differences within the native range. These comparative studies are important in order to determine if competitive abilities of exotic species are strong predictors of invasion success. The little fire ant Wasmmnia auropunctata is a highly invasive species that has spread from its original range (Central and South America) to becoming a globally distributed exotic species in recent decades. It is generally accepted that island ecosystems offer weak biotic resistance to exotic species as compared to their native range. Here, we examined this empirically by comparing the relative competitive difference of W. auropunctata and locally dominant ants, between its native range of Mexico and introduced range of Puerto Rico. Resource competition was assessed between W. auropunctata and native ants under field conditions and in the laboratory. Furthermore, we compared resource competition at different temporal intervals ranging from short-term (< 2 hours) to long-term (14-days) dynamics. Our results are in contrast to common invasion predictions on island communities because we show that native species were resistant to W. auropunctata in its introduced range of Puerto Rico. We observed that the ground-foraging ant Solenopsis invicta competitive displaced W. auropunctata in Puerto Rico during short-term experiments. Meanwhile, the native arboreal ant Linepithema iniquum withstood competitive pressure from W. auropunctata. In the native range of Mexico, W. auropunctata was superior against Solenopsis Picea and Pheidole protensa species, but was outcompeted by dominant ants Solenopsis geminata and Pheidole synanthropica. This study challenges the relative importance of competitive ability in predicting invasion success. This is one of the few detailed comparative studies that examines exotic species performance between native and introduced habitats.

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