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Questions and Answers
What distinguishes parasitism from mutualism?
What distinguishes parasitism from mutualism?
Which of the following best defines commensalism?
Which of the following best defines commensalism?
Which type of parasitism cannot survive without its host?
Which type of parasitism cannot survive without its host?
What is an essential characteristic of microparasites?
What is an essential characteristic of microparasites?
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What is the term for a commensal relationship in which one organism lives within the dwelling of another species?
What is the term for a commensal relationship in which one organism lives within the dwelling of another species?
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What does the term 'phoresy' refer to in commensalism?
What does the term 'phoresy' refer to in commensalism?
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Which of the following is an example of mutualism?
Which of the following is an example of mutualism?
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How is pathogenic parasitism characterized?
How is pathogenic parasitism characterized?
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The term 'metabiosis' in commensalism refers to what type of relationship?
The term 'metabiosis' in commensalism refers to what type of relationship?
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What is a common feature of facultative parasites?
What is a common feature of facultative parasites?
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What effect can parasites have on host population dynamics?
What effect can parasites have on host population dynamics?
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How can parasites affect ecological communities?
How can parasites affect ecological communities?
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What kind of behavior might parasitized killifish exhibit?
What kind of behavior might parasitized killifish exhibit?
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In temporary ponds, what impact do telorchis infections have on Hyla versicolor tadpoles?
In temporary ponds, what impact do telorchis infections have on Hyla versicolor tadpoles?
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What does parasitism do to the digging ability of cockles?
What does parasitism do to the digging ability of cockles?
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How did the introduction of Bothriocephalus acheilognathi affect community dynamics?
How did the introduction of Bothriocephalus acheilognathi affect community dynamics?
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In an experimental scenario, what was the effect of a protozoan parasite on the flour beetles?
In an experimental scenario, what was the effect of a protozoan parasite on the flour beetles?
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What is an indirect effect of parasitism as described in the ecological context?
What is an indirect effect of parasitism as described in the ecological context?
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Which statement best describes the relationship between parasites and ecological biodiversity?
Which statement best describes the relationship between parasites and ecological biodiversity?
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What potential outcome does the presence of trematode worms have on the physical environment in relation to mudshrimp?
What potential outcome does the presence of trematode worms have on the physical environment in relation to mudshrimp?
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What is the primary difference between endoparasites and ectoparasites?
What is the primary difference between endoparasites and ectoparasites?
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Which of the following is NOT a common ectoparasite?
Which of the following is NOT a common ectoparasite?
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What is the term used for organisms that cause near or total cessation of a host's reproductive activity?
What is the term used for organisms that cause near or total cessation of a host's reproductive activity?
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Which factor does NOT typically affect virulence in pathogenic organisms?
Which factor does NOT typically affect virulence in pathogenic organisms?
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What is defined as the measure of the 'burden of a disease' in terms of lost healthy life years?
What is defined as the measure of the 'burden of a disease' in terms of lost healthy life years?
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What adaptive significance does host gigantism serve for trematode parasites like Schistosoma spp.?
What adaptive significance does host gigantism serve for trematode parasites like Schistosoma spp.?
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Which term refers to the ability of an organism to cause disease or damage to its host?
Which term refers to the ability of an organism to cause disease or damage to its host?
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What best describes an organism capable of entering its host and continuing its development?
What best describes an organism capable of entering its host and continuing its development?
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What does the term morbidity refer to in a population?
What does the term morbidity refer to in a population?
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What is meant by the term virulence factors in parasites?
What is meant by the term virulence factors in parasites?
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Study Notes
Introduction to Parasitism
- Parasitism is a type of symbiotic relationship where one organism, the parasite, benefits at the expense of the host organism
- Parasites can affect host populations by reducing reproduction and survival
- Parasites can alter ecological communities by changing species interactions and community structure
- Parasites are often host-specific, infecting a single or a closely related group of species
Commensalism
- Commensalism is a type of symbiotic relationship where one organism benefits while the other is neither harmed nor helped.
- Commensalism does not involve a physiological interaction or dependency
- There are three main types of commensalism: Phoresy, Inquilinism and Metabiosis
Phoresy
- Phoresy is a commensal relationship where one organism, the phoront, is mechanically carried by another, larger organism.
- It is a form of commensalism where the smaller organism is transported by a larger organism
- May evolve into parasitism
Inquilinism
- Inquilinism is where one organism lives in the nest, burrow, or dwelling place of another species.
Metabiosis
- Metabiosis is a commensal relationship where one organism is dependent on another for indirectly creating or preparing an environment that it can live in.
Mutualism
- Mutualism is a type of symbiotic relationship where both organisms benefit from the association.
- It is usually obligatory, meaning that neither partner can survive without the other.
Parasitism
- Parasites cause harm to their hosts or live at their expense.
- Parasites can be benign, pathogenic, or parasitic castrators.
- Benign parasites cause little to no symptomology.
- Pathogenic parasites cause mechanical injury, immunopathology, or rob essential nutrients from the host.
- Parasitic castrators cause near or total cessation of host reproductive activity, diverting host resources to parasite growth.
Types of Parasites
- Microparasites are microscopic (e.g., bacteria, viruses, protozoa)
- Macroparasites are large enough to be seen with the naked eye (e.g., flatworms, roundworms, arthropods)
- Endoparasites live within the body of the host (e.g., in the intestinal tract, blood vessels, liver, lungs, urinary bladder)
- Ectoparasites attach to the outer surface of the host or are superficially embedded in the body surface.
Advantages and Disadvantages of Endoparasitism vs. Ectoparasitism
- Ease of parasite dispersal: Endoparasites often rely on complex life cycles with multiple host species, making dispersal more challenging than for ectoparasites who can readily disperse with their host.
- Ability and ease of parasite feeding: Ectoparasites have immediate access to host resources, whereas endoparasites may need to overcome host defenses to feed.
- Parasite vulnerability to the host immune system: Endoparasites are protected within the host body, reducing exposure to the immune system, while ectoparasites face greater vulnerability.
Parasitic Castrators
- Larval stages of some trematodes (e.g., Schistosoma spp.) castrate snail intermediate hosts resulting in host gigantism
- The adaptive significance to the parasite is that the parasite benefits from the host's increased resources, allowing for more energy allocation towards parasite reproduction and survival.
Body Snatchers
- Some parasites take over and alter host behavior, often through trophic transmission.
- “Zombie snails” is an example of a parasite manipulating the host for its own benefit through alteration of snail behavior, making them more vulnerable to predation.
Epidemiological Terms
- Infectious agent: An organism that is producing an infection or infectious disease
- Infective stage: The life cycle stage in which the parasite is capable of entering its host and then continues its development
- Infection: Entry and development or multiplication of an infectious agent in the animal's body
- Pathogen: An infectious agent causing a disease state in a host
- Pathogenicity: Ability of an organism to cause disease/damage to the host
- Disease: A pathological condition with symptoms distinct from the normal body state
- Virulence: The degree of pathology caused by an infectious agent
- Virulence factors: Molecules/factors that enable the parasite to invade and establish an infection and contribute to host pathogenesis
- Morbidity: The condition of being diseased or sick
- Mortality: The quality of being mortal or destined to die
- Control: The reduction of disease incidence, prevalence, morbidity, or mortality to a locally acceptable level
- Elimination: Reduction to zero of the incidence of a specified parasitic disease in a defined geographical area
- Eradication: Permanent, worldwide reduction to zero of the incidence of infection by a specific parasite
Morbidity and its Economic Consequences
- Parasitic infections can have significant economic consequences
- Morbidity due to parasitic infections can be measured in disability-adjusted life years (DALYs), representing the burden of a disease
- DALYs consider both years of life lost through premature mortality and years of life lived with disability, providing a comprehensive measure of disease impact
Example of Parasitic Castrators - The Parasitic Barnacle (Sylon hippolytes)
- The parasitic barnacle castrates the shrimp by attaching to its body and diverting energy and resources away from the host’s reproductive system.
- While this castration process benefits the parasitic barnacle by providing more energy for reproduction and survival, it ultimately reduces the reproductive success of the shrimp.
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Description
This quiz explores the concepts of parasitism and commensalism, focusing on their definitions, characteristics, and impacts on host organisms and ecological communities. Learn about the different types of commensal relationships, particularly phoresy, and how they can evolve into parasitism. Test your knowledge on these essential symbiotic relationships!
