Chapter 13- Parasitism

Coevolution

Populations of two interacting species evolve together, each in response to selective pressures imposed by the other

Ectoparasite

They live on the outer body surface of the host.

Endoparasites

They live inside their hosts, within cells or tissues, or in the alimentary canal

Host

It is an organism on which an herbivore, parasite, or mutualist lives and feeds.

Macroparasites

Large species such as arthropods and worms

Mircoparasites

Microscopic/small, such as bacteria.

Parasites

It consumes the tissues or body fluids of the organism on which it lives.

Parasitoids

An insect that lays one or a few eggs on or in a host organism (Itself usually an insect) which the resulting larvae remain with, eat, and almost always kill

Pathogens

are parasites that cause diseases (disorders of structure or function with distinct signs or symptoms)

Threshold density

It is the minimum number of individuals that are susceptible to a disease that must be present in a population for the disease to become established and spread.

More than “Half of Earth’s Species” are?

Parasites

Unlike predators…parasites?

Usually have higher reproductive rate than their host.

What varies from parasite to parasite?

The degree of harm that they cause to their hosts.

Parasites can feed on?

Plants (e.r aphids or nematodes) and Animals (e.g lice)

Although parasites feed on both plants and animals….parasites usually?

Specialize in one or a few hosts.

Provide an example of “Plant Ectoparasites”

Dodder

Provide an example of “Fungi Ectoparasites”

Mildew, rusts, and smuts.

What is the “Perfect Habitat” for Parasites?

The alimentary canal

What is the parasite that attaches to the host’s intestinal wall and absorbs digested food?

Tapeworms

What is the bacterium that causes the plague?

Yersinia pestis

What is the bacterium that causes tuberculosis?

Mycobacterium tuberculosis

What are the “PROS” regarding “Ectoparasites”?

They can disperse more easily (since they live on the surface of an organism)

What are the “CONS” regarding “Ectoparasites”?

They are more exposed to predators, parasites, and parasitoids.

What are the “PROS” regarding “Endoparasites”?

They are protected from the external environment and have easy access to food.

What are the “CONS” regarding “Endoparasites”?

They can be attacked by the host’s immune system.

What have “Endoparasites” evolved in order to combat their ecological cons?

1.) Various mechanisms for dispersal (including feces)

2.) Complex life cycles

3.) Enslavement of hosts

What are the “Four Types of Host Defenses”? (be sure to specify the ones that only vertebrae have)

1.) Protective outer coverings (e.g., skin, exoskeletons)

2.) Immune system (vertebrates)

3.) Biochemical defenses (vertebrates)

4.) Defensive symbionts

“Paratistes” develop “Counterdefenses” due to/becuase?

Strong selection pressures.

'‘Vertebrates” have ____ cells that can ?

Memory cells that can recognize microparasites from previous exposures

What “Type of Host defense” do plants have?

Non-specific immune responses such as antimicrobial and anti-fungal.

What is the parasite that causes the disease/sickness of “Malaria”?

Plasmodium endoparasite protists

What are the “Two challenges” that the parasite “Plasmodium” face

1.) Red blood cells do not divide or grow and do not import nutrients

2.) After infection, Plasmodium causes red blood cells to have an abnormal shape (The cell are destroyed in spleen)

What is “gene-for-gene interactions”

It is when parasites and host evolve together that they are best adapted to cope with the genotype of their local host/parasite

Trade-offs

A trait that improves host defenses or parasite counterdefenses may reduce some other aspects of growth, survival, or reproduction.

When can “Parasites” do to Local Hosts?

They drive their populations extinct and reduce their geographical ranges.

“Parasite” can also impact?

Host population cycles

A parasite that attacks a dominant competitor can?

Suppress that species which in turn causes other species to increase

Who must parasites choose as host in order to alter the physical environment?

An ecosystem engineer