scholarly journals Host manipulation by parasites in the world of dead-end predators: adaptation to enhance transmission?

2008 ◽  
Vol 275 (1643) ◽  
pp. 1611-1615 ◽  
Author(s):  
Otto Seppälä ◽  
E. Tellervo Valtonen ◽  
Daniel P Benesh
Keyword(s):  
Definitive Host ◽  
Host Manipulation ◽  
Transmission Success ◽  
Adaptive Value ◽  
Dead End ◽  
The World ◽  
Acanthocephalus Lucii ◽  
Trophically Transmitted Parasites ◽  
Benefits And Costs ◽  
Increased Susceptibility

Trophically transmitted parasites often alter their intermediate host's phenotype, thereby predisposing the hosts to increased predation. This is generally considered a parasite strategy evolved to enhance transmission to the next hosts. However, the adaptive value of host manipulation is not clear as it may be associated with costs, such as increased susceptibility to predators that are unsuitable next hosts for the parasites. We examined the ratio between the benefits and costs of host manipulation for transmission success of Acanthocephalus lucii (Acanthocephala), a parasite that alters the hiding behaviour and pigmentation of its isopod hosts. We experimentally compared the susceptibility of infected and uninfected isopods to predation by perch ( Perca fluvialis ; definitive host of the parasite) and dragonfly larvae (dead end). We found that the parasite predisposed the isopods to predation by both predators. However, the increased predation vulnerability of the infected isopods was higher towards perch. This suggests that, despite the costs due to non-host predation, host manipulation may still be advantageous for the parasite.

scholarly journals Host manipulation as a parasite transmission strategy when manipulation is exploited by non-host predators

2008 ◽  
Vol 4 (6) ◽  
pp. 663-666 ◽  
Author(s):  
Otto Seppälä ◽  
Jukka Jokela
Keyword(s):  
Predation Risk ◽  
Transmission Probability ◽  
Parasite Transmission ◽  
Host Manipulation ◽  
Predator Species ◽  
Transmission Strategy ◽  
Adaptive Value ◽  
Parasite Populations ◽  
Manipulation Strategy ◽  
Increased Susceptibility

Trophically transmitted parasites often alter their intermediate host's phenotype, thereby predisposing hosts to increased predation. This is generally considered to be a parasite strategy evolved to enhance transmission to the next host. However, the adaptive value of host manipulation is not clear, as it may be associated with costs, such as increased susceptibility to predator species that are unsuitable next hosts for the parasites. Thus, it has been proposed that, to be adaptive, manipulation should be specific by predisposing hosts more strongly to predation by target hosts (next host in the life cycle) than to non-hosts. Here we formally evaluate this prediction, and show that manipulation does not have to be specific to be adaptive. However, when manipulation is nonspecific, it needs to effectively increase the overall predation risk of infected hosts if it is to increase the parasite transmission probability. Thus, when initial predation risk is low, even highly nonspecific manipulation strategies can be adaptive. However, when initial predation risk is high, manipulation needs to be more specific to increase parasite transmission success. Therefore, nonspecific host manipulation may evolve in nature, but the adaptive value of a certain manipulation strategy can vary among different parasite populations depending on the variation in initial predation risk.

Costs of intraspecific and interspecific host sharing in acanthocephalan cystacanths

Parasitology ◽  
2001 ◽  
Vol 122 (4) ◽  
pp. 483-489 ◽  
Author(s):  
B. S. DEZFULI ◽  
L. GIARI ◽  
R. POULIN
Keyword(s):  
Intermediate Host ◽  
Definitive Host ◽  
Interspecific Interactions ◽  
Sympatric Species ◽  
Competitive Interactions ◽  
Host Size ◽  
Intermediate Hosts ◽  
Transmission Success ◽  
Additional Costs ◽  
Net Benefits

Larval helminths often share individual intermediate hosts with other larval worms of the same or different species. In the case of immature acanthocephalans capable of altering the phenotype of their intermediate hosts, the benefits or costs of host sharing can be evaluated in terms of increased or decreased probability of transmission to a suitable definitive host. Competitive interactions among the immature stages of acanthocephalans within the intermediate host could create additional costs of host sharing, however. The effects of intraspecific and interspecific interactions were measured in 3 sympatric species of acanthocephalans exploiting a population of the amphipod Echinogammarus stammeri in the River Brenta, Italy. The strength of interactions was assessed from differences in the size achieved by infective cystacanths in the intermediate host. The size of Pomphorhynchus laevis cystacanths was not correlated with host size, whereas the size of Acanthocephalus clavula and Polymorphus minutus cystacanths increased with host size. Reductions in cystacanth size caused by intraspecific competition were only detected in P. laevis, but may also occur in both A. clavula and P. minutus. When co-occurring in the same amphipod with cystacanths of A. clavula, cystacanths of P. laevis attained a smaller size than when they occurred on their own. This effect was not reciprocal, with the size of A. clavula cystacanths not being affected. This supports earlier suggestions that it is adaptive for A. clavula to associate with P. laevis in amphipod intermediate hosts, with both species going to the same fish definitive hosts. In contrast, cystacanths of P. laevis achieved their largest size when they co-occurred in an amphipod with a cystacanth of P. minutus, which has a different definitive host (i.e. birds). These findings suggest that the net benefits of sharing an intermediate host can only be estimated by taking into account both the effects on transmission success and the consequences for cystacanth development.

Teilhard De Chardin's Spirituality of the Cross

Horizons ◽  
1976 ◽  
Vol 3 (1) ◽  
pp. 1-15
Author(s):  
Robert Faricy
Keyword(s):  
Jesus Christ ◽  
Theology Of The Cross ◽  
Christian Life ◽  
Dead End ◽  
Spiritual Theology ◽  
The World ◽  
Pierre Teilhard De Chardin ◽  
The Cross

AbstractThis article studies the spiritual theology of the cross in the writings of Pierre Teilhard de Chardin. In Teilhard's books and articles the accent falls on the cross as a symbol of progress. The cross stands for Jesus' positive act of saving the world through his death; it represents, too, Christian life as a sharing in the cross of Jesus through the labor and pain of human progress. In his spiritual notes, however, Teilhard takes a different perspective. His own meditations on the cross center not on the cross as a positive symbol of personal and collective progress through struggle, but rather on death as the ultimate fragmentation, and as an apparent dead end that is the final passage to Jesus Christ.

scholarly journals Parental effects alter the adaptive value of an adult behavioural trait

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Rebecca M Kilner ◽  
Giuseppe Boncoraglio ◽  
Jonathan M Henshaw ◽  
Benjamin JM Jarrett ◽  
Ornela De Gasperin ◽  
...  
Keyword(s):  
Parental Care ◽  
Theoretical Modelling ◽  
Parental Effects ◽  
Levels Of Care ◽  
Adaptive Value ◽  
Nicrophorus Vespilloides ◽  
Low Levels ◽  
Behavioural Trait ◽  
Evolutionary Consequences ◽  
Benefits And Costs

The parents' phenotype, or the environment they create for their young, can have long-lasting effects on their offspring, with profound evolutionary consequences. Yet, virtually no work has considered how such parental effects might change the adaptive value of behavioural traits expressed by offspring upon reaching adulthood. To address this problem, we combined experiments on burying beetles (Nicrophorus vespilloides) with theoretical modelling and focussed on one adult behavioural trait in particular: the supply of parental care. We manipulated the early-life environment and measured the fitness payoffs associated with the supply of parental care when larvae reached maturity. We found that (1) adults that received low levels of care as larvae were less successful at raising larger broods and suffered greater mortality as a result: they were low-quality parents. Furthermore, (2) high-quality males that raised offspring with low-quality females subsequently suffered greater mortality than brothers of equivalent quality, which reared larvae with higher quality females. Our analyses identify three general ways in which parental effects can change the adaptive value of an adult behavioural trait: by influencing the associated fitness benefits and costs; by consequently changing the evolutionary outcome of social interactions; and by modifying the evolutionarily stable expression of behavioural traits that are themselves parental effects.

Consequences of IFRS Adoption

2016 ◽  
pp. 47-65
Author(s):  
Erick R. Outa
Keyword(s):  
Economic Stability ◽  
Ifrs Adoption ◽  
The World ◽  
World Economic ◽  
Benefits And Costs

The purpose of this chapter is to review the consequences of IFRS adoption by reviewing circumstances under which the benefits and costs accrue to firms, countries and the world. Notwithstanding, all issues raised about the consequences, IFRS adoption has had positive consequences and no wonder nearly 120 countries around the world and significant markets have adopted it. The chapter contributes to our understanding of the importance of IFRS and its effects and it is important to regulators and parties involved with world economic stability.

scholarly journals Cyclic Synthetic Peroxides Inhibit Growth of Entomopathogenic Fungus Ascosphaera apis without Toxic Effect on Bumblebees

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1954 ◽  
Author(s):  
Ivan A. Yaremenko ◽  
Mikhail Y. Syromyatnikov ◽  
Peter S. Radulov ◽  
Yulia Yu. Belyakova ◽  
Dmitriy I. Fomenkov ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Growth Inhibition ◽  
Entomopathogenic Fungus ◽  
Bombus Terrestris ◽  
Mycelium Growth ◽  
Ascosphaera Apis ◽  
The World ◽  
Fungicide Activity ◽  
Commercial Fungicide ◽  
Increased Susceptibility

In recent years, the number of pollinators in the world has significantly decreased. A possible reason for this is the toxic effects of agrochemicals reducing the immunity of insects that leads to their increased susceptibility to pathogens. Ascosphaera apis is a dangerous entomopathogenic fungus, afflicting both honeybees and bumblebees. We investigated fungicide activity of cyclic synthetic peroxides against A. apis isolated from Bombus terrestris L. The peroxides exhibited high mycelium growth inhibition of A. apis up to 94–100% at concentration 30 mg/L. EC50 values were determined for the most active peroxides. Two peroxides showed higher antifungal activity against A. apis than the commercial fungicide Triadimefon. The studied peroxides did not reduce the ability of bumblebees to fly and did not lead to the death of bumblebees. A new field of application for peroxides was disclosed.

A “mille-feuilles” of stress tolerance in the desert plant Zygophyllum dumosum Boiss.: Highlighting epigenetics

2019 ◽  
Vol 66 (1-2) ◽  
pp. 52-59 ◽  
Author(s):  
Gideon Grafi
Keyword(s):  
Stress Tolerance ◽  
High Salinity ◽  
Natural Habitat ◽  
Histone H3 ◽  
Temperature Extremes ◽  
Desert Plant ◽  
Opportunistic Behavior ◽  
Developmental Mechanisms ◽  
Adaptive Value ◽  
The World

Plants thriving in harsh desert environments provide a suitable bio-system for unraveling novel mechanisms for survival under seasonal climate change and combination of temperature extremes, low water and nutrient availability and high salinity and radiation levels. The study of the desert plant Zygophyllum dumosum Boiss in its the natural habitat of the Negev desert revealed that stress tolerance is achieved by a plethora of mechanisms (e.g. morphological, molecular and developmental mechanisms), which are probably regulated by multiple genes that act together to bring about tolerance. Of particular interest is the finding that Z. dumosum like other Zygophyllaceae species, most of which inhabit dry and semidry regions of the world, do not possess the repressive epigenetic markers of histone H3 di- and tri-methylated at lysine 9; yet they possess mono methyl H3K9. We discuss the adaptive value of lessening epigenetic constraints with regard to the opportunistic behavior that makes plants most adaptable to change.

scholarly journals An Ethical Approach to the 21st Century Humanity in the Face of Globalization: Towards Redefining the Meaning of Humanity in the Modern Times

2020 ◽  
Vol 12 (5) ◽  
pp. 103
Author(s):  
George Ohabuenyi Abah ◽  
Ignatius Ifeanyichukwu Ogbodo
Keyword(s):  
21St Century ◽  
Paradigm Shift ◽  
Modern Times ◽  
Historical Method ◽  
Positive Effects ◽  
The People ◽  
Dead End ◽  
The World ◽  
Remarkable Event ◽  
The Face

BACKGROUND: Historically, every century has a remarkable event for which it is known. These events, apart from giving a peculiar identity to a century, influences the religious, political, and socio-economic lives of the people. Apparently, the underlying element in the plurality of the world-views of the people of a century is the peculiar events of their time. In this light, the 21st century is identical with globalization. METHODOLOGY: The study used a qualitative design. The methods used were historical, expository, and critical. The historical method was used to trace some centuries before the 21st century to examine their various understandings and approaches to the concept of humanity. The expository method was used to dissect the various anchors of humanity to see the relevance of a redefinition of humanity in the modern times. Finally, the critical method was used to access the 21st century humans to know the expediency for a paradigm shift on the concept of humanity in the modern times. RESULT: This paper argues that aside the positive effects of globalization, there is an urgent need to redefine the meaning of humanity that is already defaced by its inherent activities. CONCLUSION: This research recommends that an ethical redress in the understanding of humanity in the face of today’s globalization is expedient to promote reverence for human lives. This will help to avoid the collapse of this century into a game of exploitation of each other, the dead end of narcissism and invariably the dark age of a modern time.

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