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ecology ch. 13
Terms in this set (37)
Some parasites can alter the _______ of their host in order to complete their life cycles
organisms that live in or on other organisms. More than half of Earth's species
parasite that cause disease
Large species such as arthropods and worms
microscopic, such as bacteria
insects whose larvae feed on a single host and almost kill it; specialized group of parasites
Many parasites are closely adapted to particular host species; even parasites have parasites
Why are there so many species of parasites?
more exposed to predators, parasites, and parasitoids
Parasites that feed on external surface of host.
both herbivores and parasites
ex: aphids, beetles, etc
Animals that are ectoparasites on plants can be considered to be __________ and __________.
more protected from the external environment and have easy access to food but can be attacked by immune system
A parasite that lives within a host, within cells or tissues or in the alimentary canal
get water and nutrients from the host but can also photosynthesize
many live with the host's tissues or cells
Many disease organisms are what?
most attach and rob the host of nutrients
what is a excellent habitat for parasites?
Bacteria can cause soft rot
some bacteria invade vascular tissues, disrupting the flow of water and nutrients, causing wilting and death
What are plant endoparasites?
Which is better at dispersing, ectoparasites or endoparasites?
have evolved various mechanisms for dispersal, including complex life cycles and enslavement of hosts
1) ease of dispersal
2) safe from host's immune system
1) vulnerability to natural enemies
2) exposure to external environment
3) feeding more difficult
advantage and disadvantages of ectoparasitism
1) ease of feeding
2) protected from external environment
3) safer from natural enemies
4) vulnerability to host's immune system
1) dispersal more difficult
2) vulnerability to host's immune system
advantages and disadvantages of endoparasitism:
Found in vertebrate immune systems that can recognize micro parasites from previous exposures
1) resistance genes
2) nonspecific immune response such as antimicrobial and antifungal
3) chemical signals that "warn" nearby cells of imminent attack (using secondary compounds)
4) chemicals that stimulate deposition of lignin, making a barrier to an invader's spread
Plants defense system against parasites
the protozoan that causes malaria, has a complex life cycle with two host-mosquitoes and humans
Populations of two interacting species
evolve together, each in response to
selection imposed by the other
A specific defensive response that makes particular plant genotypes resistant to particular parasite genotypes.
an arms race may stop because of trade-offs
a trait that ______ host defense or parasite counterdefenses may _____ some other aspects of growth, survival, or reproduction
1) susceptible individuals
2) infected individuals
3) recovered and immune individuals
How are host populations divided up?
2) latent period (individual is infected but cannot spread the disease)
3) vertical transmission
What can affect the likelihood of infection in the host?
A disease will spread only if the density of
susceptible hosts exceeds a critical ___________.
disease is transferred from mother to newborn
1) slaughtering of animals that have the disease, especially if the disease can spread to humans
2) for humans, mass vaccination programs reduce density of susceptible individuals
what are ways to control susceptible individuals to keep them below the threshold density?
1) increase recovery rate of infected individuals, who then have immunity, by early detection and improved treatments
2) decrease infection rates by quarantining infected individuals or changing behaviors to reduce disease transmission
how can public health measures raise the threshold density?
species interaction, community composition, and physical environment
By reducing host performance and growth rates, parasites can change the outcome of __________, _____________, and even the ____________.
predators may be less able to catch their prey, or prey less able to escape predation
parasites can alter what by decreasing the physical condition of infected individuals
change in community structure
A parasite that attacks a dominant
competitor can suppress that species,
causing other species to increase
Ecosystem engineer species can change
the physical environment, such as a beaver building a dam
species changing the physical environment:
affects distribution of diseases and can alter species interactions
how can climate change affect parasites?
Parasites that alter host behavior when its attached or inside
How do enslaver parasites manipulate the behavior of their hosts?
previous evolutionary change
enslaver parasites have many adaptations to cope with host defense
interactions between enslaver parasites and their hosts provide evidence of?
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