scholarly journals The visual ecology of selective predation: Are unhealthy hosts less stealthy hosts?

2021 ◽  
Author(s):  
Nina Wale ◽  
Rebecca Fuller ◽  
Sonke Johnsen ◽  
McKenna Turrill ◽  
Meghan Duffy
Keyword(s):  
Disease Transmission ◽  
Ecological Interactions ◽  
Water Color ◽  
Selective Predation ◽  
Chromatic Contrast ◽  
Visual Models ◽  
Pasteuria Ramosa ◽  
Mechanistic Basis ◽  
Induced Changes ◽  
Infected Prey

Predators can strongly influence disease transmission and evolution, particularly when they prey selectively on infected hosts. Although selective predation has been observed in numerous systems, why predators select infected prey remains poorly understood. Here, we use a model of predator vision to test a longstanding hypothesis as to the mechanistic basis of selective predation in a Daphnia-microparasite system, which serves as a model for the ecology and evolution of infectious diseases. Bluegill sunfish feed selectively on Daphnia with a variety of parasites, particularly in water uncolored by dissolved organic carbon. The leading hypothesis for selective predation in this system is that infection-induced changes in the appearance of Daphnia render them more visible to bluegill. Rigorously evaluating this hypothesis requires that we quantify the effect of infection on the visibility of prey from the predator’s perspective, rather than our own. Using a model of the bluegill visual system, we show that the three common parasites, Metschnikowia bicuspidata, Pasteuria ramosa and Spirobacillus cienkowskii, increase the opacity of Daphnia, rendering infected Daphnia darker against the background of downwelling light. As a result of this increased brightness contrast, bluegill can see infected Daphnia at greater distances than uninfected Daphnia – between 19-33% further, depending on the parasite. Pasteuria and Spirobacillus also increase the chromatic contrast of Daphnia. Contrary to expectations, the visibility Daphnia was not strongly impacted by water color in our model. Our work generates hypotheses about which parasites are most likely affected by selective predation in this important model system and establishes visual models as a valuable tool for understanding ecological interactions that impact disease transmission.

scholarly journals Pulmonary responses to acute ozone exposure in fasted mice: effect of leptin administration

2007 ◽  
Vol 102 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Richard A. Johnston ◽  
Todd A. Theman ◽  
Raya D. Terry ◽  
Erin S. Williams ◽  
Stephanie A. Shore
Keyword(s):  
Bronchoalveolar Lavage ◽  
Continuous Infusion ◽  
Pulmonary Inflammation ◽  
Airway Responsiveness ◽  
Ozone Exposure ◽  
Pulmonary Mechanics ◽  
Serum Leptin ◽  
Mechanistic Basis ◽  
Inflammatory Profile ◽  
Induced Changes

Leptin is a satiety hormone that also has proinflammatory effects, including augmentation of ozone-induced pulmonary inflammation. The purpose of this study was to determine whether reductions in endogenous levels of leptin can attenuate pulmonary responses to ozone. To reduce serum leptin, we fasted mice overnight before ozone exposure. Fasting caused a marked reduction in serum leptin to approximately one-sixth the levels observed in fed mice, and continuous infusion of leptin via Alzet micro-osmotic pumps restored serum leptin to, but not above, fed levels. Ozone exposure (2 ppm for 3 h) caused a significant, ∼40% increase in pulmonary resistance ( P < 0.01) and increased airway responsiveness in fasted but not in fed mice. The increased effect of ozone on pulmonary mechanics and airway responsiveness in fasted mice was not observed when leptin was restored via continuous infusion. Ozone exposure caused pulmonary inflammation, as evident by increases in bronchoalveolar lavage cells, protein, and soluble tumor necrosis factor receptors. There was no effect of fasting status on ozone-induced changes in the bronchoalveolar lavage inflammatory profile, and leptin treatment did not alter these responses. Our results indicate that fasting augments ozone-induced changes in pulmonary mechanics and airway responsiveness in mice. These effects of fasting are the result of declines in serum leptin. The mechanistic basis for this protective effect of leptin in fasted mice remains to be determined but is not related to effects on ozone-induced inflammation.

scholarly journals Behavioural mechanisms underlying parasite-mediated competition for refuges in a coral reef fish

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Graham E. Forrester ◽  
Erin Chille ◽  
Katie Nickles ◽  
Kiran Reed
Keyword(s):  
Coral Reef ◽  
Parasitic Copepod ◽  
Interactive Effects ◽  
Predatory Fish ◽  
Ecological Interactions ◽  
Host Manipulation ◽  
Predator Prey ◽  
Prey Interaction ◽  
Induced Changes ◽  
Host Behaviour

Abstract Parasites have been increasingly recognized as participants in indirect ecological interactions, including those mediated by parasite-induced changes to host behaviour (trait-mediated indirect interactions or TMIIs). In most documented examples, host behaviours altered by parasites increase susceptibility to predation because the predator is also a host (host-manipulation). Here, we test for a TMII in which a parasitic copepod modifies the predator-prey interaction between a small goby host and several larger predatory fish. Gobies compete for crevices in the reef to avoid predation and goby mortality increases more rapidly with increasing refuge shortage for parasitized gobies than for those free of parasites. We found interactive effects of refuge shortage and parasitism on two behaviours we predicted might be associated with parasite-mediated competition for refuges. First, as refuge-shortage increases, the rate of aggression among gobies increases and parasitism intensifies this interaction. Second, goby proximity to refuges increases as refuges become scarce, but parasitism nullifies this increase. In combination, these parasite-induced changes in behaviour may explain why parasitized gobies are poor competitors for refuges. Because the parasite is not trophically transmitted via host manipulation, these altered behaviours in parasitized gobies are likely coincidental to infection.

Effects of domestication on parr maturity, growth, and vulnerability to predation in Atlantic salmon

2014 ◽  
Vol 71 (9) ◽  
pp. 1371-1384 ◽  
Author(s):  
Paul V. Debes ◽  
Jeffrey A. Hutchings
Keyword(s):  
Atlantic Salmon ◽  
Prey Size ◽  
Wild Strain ◽  
Male Reproductive Success ◽  
Selective Predation ◽  
Predation Mortality ◽  
In The Wild ◽  
Related Stress ◽  
Induced Changes ◽  
Lower Size

Domestication can change fitness-related traits. We investigated domestication-induced changes in fitness-related traits in Atlantic salmon (Salmo salar) under naturally enriched laboratory conditions with and without threat of predation. Selection in two strains for rapid growth for three and five generations resulted in two and three times larger sizes of under-yearling parr relative to their wild ancestor. An initially larger size and ability to outgrow prey size more rapidly resulted in lower size-selective predation mortality for domesticated individuals. Growth under threat of predation was only reduced for wild individuals, suggesting that domestication co-selects for predator-related stress resistance. Size-adjusted male parr maturation probability was 34% in the wild strain, but significantly reduced to 10% and 7% after three and five generations of domestication, respectively. Together, freshwater-stage-specific survival for individuals with a domesticated background relative to individuals with a wild genetic background might be higher in the presence of gape-limited predators preferring small individuals, but male reproductive success might be lower for domesticated individuals as their reproduction potential during the freshwater phase is reduced.

scholarly journals Parasite transmission in a natural multihost–multiparasite community

2017 ◽  
Vol 372 (1719) ◽  
pp. 20160097 ◽  
Author(s):  
Stuart K. J. R. Auld ◽  
Catherine L. Searle ◽  
Meghan A. Duffy
Keyword(s):  
Disease Transmission ◽  
Transmission Rate ◽  
Ceriodaphnia Dubia ◽  
Reservoir Host ◽  
Parasite Transmission ◽  
Transmission Potential ◽  
Parasite Fitness ◽  
Dead End ◽  
Pasteuria Ramosa ◽  
Parasite Spillover

Understanding the transmission and dynamics of infectious diseases in natural communities requires understanding the extent to which the ecology, evolution and epidemiology of those diseases are shaped by alternative hosts. We performed laboratory experiments to test how parasite spillover affected traits associated with transmission in two co-occurring parasites: the bacterium Pasteuria ramosa and the fungus Metschnikowia bicuspidata . Both parasites were capable of transmission from the reservoir host ( Daphnia dentifera ) to the spillover host ( Ceriodaphnia dubia ), but this occurred at a much higher rate for the fungus than the bacterium. We quantified transmission potential by combining information on parasite transmission and growth rate, and used this to compare parasite fitness in the two host species. For both parasites, transmission potential was lower in the spillover host. For the bacterium, virulence was higher in the spillover host. Transmission back to the original host was high for both parasites, with spillover influencing transmission rate of the fungus but not the bacterium. Thus, while inferior, the spillover host is not a dead-end for either parasite. Overall, our results demonstrate that the presence of multiple hosts in a community can have important consequences for disease transmission, and host and parasite fitness. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.

scholarly journals CO<sub>2</sub> effects on diatoms: a synthesis of more than a decade of ocean acidification experiments with natural communities

Ocean Science ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 1159-1175 ◽  
Author(s):  
Lennart Thomas Bach ◽  
Jan Taucher
Keyword(s):  
Ocean Acidification ◽  
Size Structure ◽  
Ecological Interactions ◽  
High Co2 ◽  
Marine Food Web ◽  
Diatom Communities ◽  
Carbon Pump ◽  
Marine Food ◽  
Taxonomic Affiliation ◽  
Induced Changes

Abstract. Diatoms account for up to 50 % of marine primary production and are considered to be key players in the biological carbon pump. Ocean acidification (OA) is expected to affect diatoms primarily by changing the availability of CO2 as a substrate for photosynthesis or through altered ecological interactions within the marine food web. Yet, there is little consensus how entire diatom communities will respond to increasing CO2. To address this question, we synthesized the literature from over a decade of OA-experiments with natural diatom communities to uncover the following: (1) if and how bulk diatom communities respond to elevated CO2 with respect to abundance or biomass and (2) if shifts within the diatom communities could be expected and how they are expressed with respect to taxonomic affiliation and size structure. We found that bulk diatom communities responded to high CO2 in ∼60 % of the experiments and in this case more often positively (56 %) than negatively (32 %) (12 % did not report the direction of change). Shifts among different diatom species were observed in 65 % of the experiments. Our synthesis supports the hypothesis that high CO2 particularly favours larger species as 12 out of 13 experiments which investigated cell size found a shift towards larger species. Unravelling winners and losers with respect to taxonomic affiliation was difficult due to a limited database. The OA-induced changes in diatom competitiveness and assemblage structure may alter key ecosystem services due to the pivotal role diatoms play in trophic transfer and biogeochemical cycles.

A DYNAMICAL THEORY OF HETEROCHRONY: TIME-SEQUENCING CHANGES IN ECOLOGY, DEVELOPMENT AND EVOLUTION

1993 ◽  
Vol 01 (04) ◽  
pp. 451-487 ◽  
Author(s):  
P. ANTONELLI ◽  
R. BRADBURY ◽  
V. KŘIVAN ◽  
H. SHIMADA
Keyword(s):  
Growth And Development ◽  
Present Theory ◽  
Dynamical Theory ◽  
Ecological Interactions ◽  
Projective Differential Geometry ◽  
Population Densities ◽  
Invertebrate Animals ◽  
Induced Changes ◽  
Natural Description ◽  
Development And Evolution

This work provides a foundation for a quantitative dynamical theory of heterochronic processes in the evolution of colonial invertebrate animals including Bryozoans, Siphonophores and Ants. These processes are environmentally induced changes in the time-sequencing of growth and development which can produce alterations in the morphotypes or castes within an individual colony. Motivation comes from Křivan’s theory of environmentally induced constraints on population densities for ecological interactions, but the present theory is second order with allometric production variables xi and population densities for morphotypes, Ni. We are able to unite ecological theory and the allometric form of the Wilson Ergonomic Theory via projective differential geometry and Wagner spaces which provide a natural description of environmentally induced time-sequencing changes altering the allometric curve of a species. Such changes define a model of heterochronic processes important in paleontology.

ECO-EPIDEMIOLOGICAL MODELS OF SALTON SEA WITH INFECTED PREY

2013 ◽  
Vol 21 (01) ◽  
pp. 1350003 ◽  
Author(s):  
Q. J. A. KHAN ◽  
E. BALAKRISHNAN ◽  
AZZA HAMOOD AL HARTHI
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Numerical Simulations ◽  
Disease Transmission ◽  
Salton Sea ◽  
Bifurcation Parameter ◽  
Epidemiological Models ◽  
Analytical Results ◽  
Infected Prey

Two models for the interaction of susceptible and infected Tilapia population with Pelican population are studied. Here, we considered that Pelican interact with both susceptible and infected Tilapia in proportion to their abundance. Stability near nonzero equilibria is presented. In the second model, time delay is incorporated in the disease transmission term and Hopf bifurcation is analyzed by taking time delay as a bifurcation parameter. Numerical simulations are performed to support the analytical results.

scholarly journals CO<sub>2</sub> effects on diatoms: A Synthesis of more than a decade of ocean acidification experiments with natural communities

2019 ◽  
Author(s):  
Lennart Bach ◽  
Jan Taucher
Keyword(s):  
Ocean Acidification ◽  
Size Structure ◽  
Ecological Interactions ◽  
High Co2 ◽  
Marine Food Web ◽  
Diatom Communities ◽  
Carbon Pump ◽  
Marine Food ◽  
Taxonomic Affiliation ◽  
Induced Changes

Abstract. Diatoms account for 40 % of marine primary production and are considered to be key players in the biological carbon pump. Ocean acidification (OA) is expected to affect diatoms primarily by changing the availability of CO2 as a substrate for photosynthesis or through altered ecological interactions within the marine food web. Yet, there is little consensus how entire diatom communities will respond to increasing CO2. To address this question, we synthesized the literature from over a decade of OA-experiments with natural diatom communities to uncover: 1) if and how bulk diatom communities respond to elevated CO2; 2) if shifts within the diatom communities could be expected and how they are expressed with respect to taxonomic affiliation and size structure. We found that diatom communities responded to high CO2 in ~60 % of the experiments and in this case more often positively (56 %) than negatively (32 %; 12 % did not report the direction of change). Shifts among different diatom species were observed in 65 % of the experiments. Our synthesis supports the hypothesis that high CO2 particularly favors larger species as 12 out of 13 experiments which investigated cell size found a shift towards larger species. Unraveling winners and losers with respect to taxonomic affiliation was difficult due to a limited database, but there is evidence that the genus Pseudo-nitzschia could be among the losers. We conclude that OA-induced changes in diatom competitiveness and assemblage structure must be classified as a “risk for ecosystem services” due to the pivotal role diatoms play in trophic transfer and biogeochemical cycles.

RISK OF DISEASE-SELECTIVE PREDATION IN AN INFECTED PREY-PREDATOR SYSTEM

2009 ◽  
Vol 17 (01) ◽  
pp. 111-124 ◽  
Author(s):  
SHARIFUL ALAM
Keyword(s):  
Risk Factors ◽  
Mathematical Model ◽  
Time Delay ◽  
Discrete Time ◽  
Selective Predation ◽  
Discrete Time Delay ◽  
Risk Of Disease ◽  
The Mathematical Model ◽  
Predator System ◽  
Infected Prey

In this paper the mathematical model of disease-selective predation as proposed by Roy and Chattopadhyay10 is considered to identify the true risk of selective predation where the predator can recognize the infected prey and avoids those during predation. Furthermore, the model is modified by adding a discrete time delay in the term involving the gestation of prey by the predator and analyzed both numerically and analytically to review the risk factors.

Toxic Trojans: can feral cat predation be mitigated by making their prey poisonous?

2015 ◽  
Vol 42 (8) ◽  
pp. 689 ◽  
Author(s):  
J. L. Read ◽  
D. Peacock ◽  
A. F. Wayne ◽  
K. E. Moseby
Keyword(s):  
Threatened Species ◽  
Disease Transmission ◽  
Prey Species ◽  
Selective Predation ◽  
Live Prey ◽  
Feral Cat ◽  
Feral Cats ◽  
Wildlife Species ◽  
Baited Traps

Predation, along with competition and disease transmission from feral domestic cats (Felis catus), poses the key threat to many in situ and reintroduced populations of threatened species globally. Feral cats are more challenging to control than pest canids because cats seldom consume poison baits or enter baited traps when live prey are readily available. Novel strategies for sustainably protecting threatened wildlife from feral cats are urgently required. Emerging evidence suggests that once they have successfully killed a challenging species, individual feral cats can systematically eradicate threatened prey populations. Here we propose to exploit this selective predation through three targeted strategies to improve the efficacy of feral cat control. Toxic collars and toxic implants, fitted or inserted during monitoring or reintroduction programs for threatened species, could poison the offending cat before it can effect multiple kills of the target species. A third strategy is informed by evidence that consumption of prey species that are relatively tolerant to natural plant toxins, can be lethal to more sensitive cats. Within key habitats of wildlife species susceptible to cat predation, we advocate increasing the accessibility of these toxins in the food chain, provided negative risks can be mediated. Deliberate poisoning using live and unaffected ‘toxic Trojan prey’ enables ethical feral cat management that takes advantage of cats’ physiological and behavioural predilection for hunting live prey while minimising risks to many non-targets, compared with conventional baiting.

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