Impact of Pathogens on Biological Communities

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  • 0:01 Pathogens
  • 0:30 Pathogens & Aquatic…
  • 1:35 Pathogens & Plant Communities
  • 2:07 Pathogens & Human Communities
  • 3:36 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Have you ever thought about how something like a tiny virus can impact whatever organism it infects? And have you thought about how that will affect the health of an entire community? This lesson explores these topics.


While this isn't completely true all of the time, in medicine, we often focus on an individual when treating a disease. So, if you've got a bacterial infection, you go the doctor, the doctor prescribes you antibiotics, and you're cured. Hurrah!

There's little thought of that bacterial pathogen, a disease-causing agent, impacting the entire community's health. However, pathogens can most definitely impact the health of an entire biological community, be it aquatic, plant, or human, not just one individual within the community. This lesson will give you examples of how this is the case.

Pathogens & Aquatic Communities

Let's start by examining how pathogens affect the health of an entire aquatic community. There is a disease called white band disease, which kills off coral. It's caused by an unknown pathogen, but its effects are far more evident.

Firstly, the pathogen kills coral by causing their tissue to slough off. Some types of coral have almost completely disappeared from various parts of the Caribbean as a result.

You'd think that, just like our simple bacterial infection from the intro, it would only affect the coral. Alas, this isn't the case. When the corals die, an important habitat for fish and lobsters disappears, and biodiversity plummets. It not only plummets, but it also changes. You see, when the corals die off, they are overgrown by algae. This means animals that feed on algae come into the area, animals like surgeonfish.

To recap, a pathogen can affect the organism it harms, the animals that depend on that organism, and it can change the biodiversity of an entire ecosystem as a result. It's a triple whammy of sorts.

Pathogens & Plant Communities

This triple whammy happens in terrestrial ecosystems as well. A fungus-like pathogen, called Phytophthora ramorum, is responsible for sudden oak death. Perhaps the name kind of gives away what happens here. Suffice it to say, millions of oak trees and other trees have been completely killed off by this pathogen in California alone.

Again, many of the oak trees are gone. But there's always more to the story. Because of this pathogen, birds that called these ecosystems home, like the acorn woodpecker, decreased in number as well.

Pathogens & Human Communities

Of course, let's not forget about the fact that we as humans, even if we live in big cities, are still part of the world's ecosystem. Zoonotic pathogens, pathogens that can be transferred from an animal to a human, can affect us in serious, sometimes deadly, ways.

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