Community Interactions: Exploitation (+/-) - Online Tutor, Practice Problems & Exam Prep

Exploitation in ecological interactions includes predation, herbivory, and parasitism, where one organism benefits at the expense of another. Predation involves a predator killing and consuming prey, leading to coevolutionary adaptations. Herbivory occurs when herbivores consume plants, prompting plants to develop defenses like thorns and toxins. Parasitism features organisms living on or in hosts, with ectoparasites and endoparasites typically not fatal, while parasitoids often lead to host death. These interactions illustrate the dynamic relationships within ecosystems, emphasizing the importance of adaptations for survival.

Community Interactions: Exploitation (+/–)

This video, we're going to talk about the second type of community interaction in our lesson, which is exploitation. And so exploitation is also sometimes referred to as consumption in some textbooks. And this is an interaction or relationship where one organism benefits from the interaction at the expense of the other organism being harmed by the interaction. And so exploitation is a plus minus interaction. Now, really, there are 3 different forms of exploitation, which are predation, herbivory, and parasitism.

And we'll get to talk more about each of these 3 different types of exploitation in their own separate videos moving forward in our course starting with predation. So I'll see you all there.

1) Exploitation (+/-): Predation

This video, we're going to talk about the first type of exploitation in our lesson, which is predation. And so predation is when one organism, which we call the predator, kills and eats another organism, which we call the prey. And so predators and prey in a community are constantly in what we call a coevolutionary arms race, which refers to this cycle of reciprocal adaptations, where predators are constantly evolving adaptations to help them better catch their prey, while simultaneously, prey are constantly evolving adaptations to help them better escape their predators. And so we call this coevolution, which refers to when 2 or more interacting species are constantly evolving in response to each other. And so as an example, why are cheetahs and springboks so fast?

Well, they're not arbitrarily fast. The answer to this question is that cheetahs need to be fast in order to catch and eat their prey like the springboks. And springboks need to be fast because they need to be able to escape their predators like the cheetahs. And so it's simply the case that cheetahs and springboks that weren't fast enough didn't survive long enough to breed, and so that left us with only fast cheetahs and fast springboks. And these 2 are still in a coevolutionary arms race today.

And so this here concludes our lesson on predation, and I'll see you all in our next video.

Predator & Prey Adaptations

Are you ready? In this video, we're going to briefly talk about some pretty remarkable predator and prey adaptations that help them survive. And so on the left-hand side, we've got a few predators, and on the right-hand side, we've got a few prey. And some predators like this Townsend's big-eared bat right here have evolved this mind-blowing ability which we call echolocation. And this is where the bat emits these high-frequency sound waves that bounce off objects in the surroundings and return back to the bat as echoes, allowing the bat to create these really detailed sound maps of their surroundings, allowing them to navigate and hunt their prey even in complete total darkness, which is just crazy to think about.

And they can use their agility to catch their prey before they even know it. Now, other predators like this cougar here have evolved sharp teeth and claws, stealth, and night vision, all of which help them catch their prey. Now some snakes like this Indonesian pit viper here have venom, heat-sensing abilities in which they can see the heat signatures of their prey even in complete darkness, which allows them to accurately strike with their high attack speed. Now moving on to the prey, at first, I thought our illustrator made a pretty rare mistake in including another snake. However, it turns out this is not a snake at all.

This is actually a harmless caterpillar that is mimicking a snake. And so this mimicry is an incredible evolutionary adaptation that allows this caterpillar to deter its predators. Now, this Indian pangolin right here has a hard outer shell that acts as mechanical defense to protect it from predators, and it has remarkable climbing abilities, which allow it to get away from predators that hunt on the ground. Now last but not least, we have this common wall gecko here, which has cryptic coloration or camouflage, which allows the wall gecko to blend into its surroundings and hide from its predators. It also has something known as caudal autonomy, where the term 'caudal' refers to the tail and 'autonomy' is referring to the voluntary self-amputation.

And so caudal autonomy allows this wall gecko to voluntarily amputate its tail. Basically, it can drop its tail and use the tail as a distraction for predators as the wall gecko scurries away. And then later, the tail can regenerate. It also has incredible wall-crawling abilities, which help it escape from its predators. And so what we're seeing here is that this coevolutionary arms race between predators and prey has allowed all of these remarkable abilities to arise in both predators and prey, and this is just a small subset.

And so this here concludes this video, and I'll see you all in our next one.

Bats have evolved to use echolocation (emitting high-frequency sounds & listening to the returning echoes) to catch their prey. Some species of moth can perceive the high-pitched echolocation noise emitted by bats, helping them avoid becoming easy prey. This case is an example of _____.

• A. Competitive exclusion.
• B. Camouflage.
• C. Mimicry.
• D. Coevolution.

Prey Defense Mechanisms

This video, we're going to talk about a few other prey defense mechanisms that you should know about. Many prey exhibit behavioral adaptations, such as running or hiding from their predators, living as part of a group or a herd, and displaying active self-defense against their predators. Other prey will exhibit what's known as aposematic coloration as a defense mechanism, which is a warning coloration or an alarm coloration, in which the prey uses really bright colors to signal to their predators that it is unpalatable and should not be eaten. You can think that the "a" in aposematic is for the "a" in alarm. Other prey use mimicry as a defense mechanism, in which the prey is imitating either another animal, plant, or inanimate object.

There are two major forms of mimicry, which we highlight down below. The first is Batesian mimicry. In this type of mimicry, a harmless species mimics a harmful species. For example, this harmless little caterpillar right here is mimicking this harmful snake, and that helps this harmless caterpillar to deter many of its predators. On the other hand, Mullerian mimicry is when two or more harmful or unpalatable species share a similar coloration pattern. For example, this bee, this wasp, and this hornet are three different species that share a similar black and yellow striped pattern.

This type of mimicry, Mullerian mimicry, helps these three different species build their reputation as a harmful and unpalatable set of species. In Batesian mimicry, only the mimic is benefiting from this mimicry. However, in Mullerian mimicry, all of the species involved are benefiting from this mimicry. Down below, we have a little memory tool to help you differentiate these two types of mimicry. You can think of Batesian mimicry as a bluff, and so the "b" in Batesian is for the "b" in bluff. This harmless little caterpillar here is bluffing and imitating a harmful snake.

For Mullerian mimicry, you can think it has mutual benefits. You can think of the "m" in Mullerian as for the "m" in mutual benefits. All three of these different species here are benefiting from this type of mimicry. This here concludes our lesson, and I'll see you all in our next video.

Some stick insects can change color to blend in with their surroundings. This is an example of:

• A. Cryptic coloration.
• B. Batesian mimicry.
• C. Müllerian mimicry.
• D. Aposematic coloration.

There are over 175 species of poison dart frogs, all with bright coloration that warns potential predators to stay away. It's not just an act, though; poison dart frogs are extremely toxic and most animals that attempt to eat one will end up paralyzed or dead. Which 2 defense mechanisms do poison dart frogs exhibit from the options below?

• A. Aposematic coloration & Batesian mimicry.
• B. Aposematic coloration & Müllerian mimicry.
• C. Aposematic coloration & mechanical defense.
• D. Cryptic coloration & Müllerian mimicry.

2) Exploitation (+/-): Herbivory

In this video, we're going to talk about the second type of exploitation in our lesson, which is herbivory. Herbivory is when an organism, which we call an herbivore, consumes either plants, algae, or photosynthetic bacteria. Much like predators and prey are in a coevolutionary arms race, herbivores and plants are also somewhat in a coevolutionary arms race where they're constantly evolving in response to each other and have evolved several different adaptations to help them survive. Many herbivores have evolved specialized digestive systems or specialized teeth that are very well adapted for consuming specific plants. Plants can't just get up and run away from the herbivores, so they've evolved very strategic means of deterring herbivores, such as having physical defenses like thorns or spikes, and other plants have chemical defenses such as toxins.

Notice down below on the left-hand side over here, we're showing you an herbivore with these really great looking yellow teeth here. Overall, it has a very tough mouth and very tough teeth, which is very well adapted for consuming specific plants. Now over here on the right-hand side, we're showing you a cactus, which has physical defenses using these thorns here to deter herbivores. They are in the coevolutionary arms race and are constantly evolving in response to each other. This video concludes our lesson on herbivory, and we'll be able to learn more moving forward.

So see you all in our next video.

3) Exploitation (+/-): Parasitism

This video, we're going to talk about the third and final type of exploitation in our lesson, which is parasitism. And so a parasite is an organism that lives in or on another organism, which we call the host, stealing or taking resources from the host. Now, in this video, we are going to talk about three different types of parasites, which are ectoparasites, endoparasites, and parasitoids. Now an ectoparasite is a parasite that lives outside of the host since the root "ecto" means outside. For example, ticks are an example of an ectoparasite since they live outside of their host, which in this case would be this cow here.

Now, an endoparasite, on the other hand, is going to live inside of the host, since the root "endo" means inside. For example, roundworms live inside the digestive system of their host, here a dog, and so they are considered endoparasites. Now, ecto- and endoparasites are often not going to be fatal to the host. So usually, the host can live alongside ecto and endoparasites for extended periods of time. Now, on the other hand, a parasitoid is an organism that lives as a parasite early on in its development during the larval stage.

And so, a parasitoid will lay eggs on or in a host, and then the larvae that hatch from those eggs will feed on the host and steal resources from the host until the host is dead. And so, unlike ecto and endoparasites, which are usually not fatal to the host, a parasitoid is usually fatal to the host. As an example, we're going to look at these braconid wasp larvae. A braconid wasp will lay eggs on or in a host. Here the host is a caterpillar, and you can see one of these eggs we're zooming into right here, and you can see the larvae inside of the egg.

Now, when that larva hatches from this egg, it is going to consume and steal resources from the caterpillar until the caterpillar is dead. And so, again, we refer to this as a parasitoid. So this here concludes our brief lesson on parasitism, and I'll see you all in our next video.

Community Interactions: Exploitation (+/-) Example 1

So here we have an example problem that asks, which of the following is an example of a parasitoid? And we've got these 4 potential answer options down below. Now of course, recall from our last lesson video that a parasitoid is an organism that lives as a parasite early on in its development during the larval stage. And often these parasitoids are fatal to their hosts. Now keeping that in mind, notice option a says, a tapeworm living inside a human's intestine, feeding on the food ingested by the human.

Now this is an example of an endoparasite, not an example of a parasitoid. And so for that reason, we can eliminate answer option a. It's an endoparasite because this parasite is living inside of the human's intestine. And although the tapeworm is negative to its host, negative to the human, it's not immediately fatal to the human. And the tapeworms can live inside the human's digestive systems for extended periods of time.

So again, it's not a parasitoid, and we can move on to option b. Now option b says a nematode, which is a type of roundworm, inside an ant causing the ant to display its reddened posterior area in the hope a bird eats it, which completes the complex life cycle of the nematode. Once again, here we have an endoparasite because the nematode is a parasite living inside of the organism, its host. But again, it's not a parasitoid as it's not living as a parasite only during its early developmental stage as a larva. Now moving on, option c says a tick that bites a dog and extracts its blood.

We know from our last lesson video that a tick is an example of an ectoparasite because it lives on the outside of its host, the dog. So again, we can eliminate option c. And, of course, this leaves answer option d, which says a wasp that lays its eggs on or in a caterpillar. And the larva that hatch from those eggs then eat the caterpillar when they hatch, again, killing the caterpillar. It's fatal to it.

This example here we covered in our last lesson video and it is the correct answer here for a parasitoid. So, we can indicate that d here is the correct answer. That concludes this example, and I'll see you all in our next video.

Which of the following is not an example of exploitation?

• A. A roundworm living inside a dog's intestine, taking nutrients from the dog while harming it in the process.
• B. A giraffe eating leaves off a tree.
• C. A robin swooping down to eat an earthworm.
• D. These are all examples of exploitation.