Animal Behavior: Videos & Practice Problems

Animal behavior, influenced by ecological pressures, can be categorized into innate and learned behaviors. Proximate causation examines the mechanisms behind behaviors, while ultimate causation explores their evolutionary significance. Foraging behaviors, shaped by natural selection, optimize energy gain against predation risks. Mating systems, such as monogamy and polygamy, involve sexual selection where mate choice and competition play crucial roles. Altruism, a behavior with fitness costs to the actor, can enhance the survival of relatives, illustrating inclusive fitness and kin selection principles.

Behavior

Hi. In this lesson, we'll be talking about animal behavior. Now behavior is defined as the actions an organism will take in response to stimuli, and this can include interactions with other organisms and the environment. Now behavioral ecology is going to study animal behavior, and it's going to be interested in the ecological pressures that influence it. Behavioral ecologists are really going to be interested in asking two types of questions. They're going to want to know about what they term proximate causation, which is how behaviors occur in mechanistic terms, like what genetic factors control this behavior, or what neurological factors are involved. So they want to know what causes the behavior, and how does this behavior develop? You know, genetically, evolutionarily, how did this, you know, biochemically, physiologically develop? Now they're also going to be interested in the why of this. So proximate causation is looking at how this happens step by step in a mechanistic sense. Ultimate causation is why these behaviors occur, what function do they serve, and how did they evolve, not in a mechanistic sense, but in terms of how they affected this organism's survival. Right? So we want to know how these behaviors are going to affect fitness, and how did they evolve in the sense of what pressures encouraged them and discouraged other behaviors. You know, what events led to them being the behaviors that best served this organism.

Now, here you can see an example of very well-studied behavior, which is exhibited by geese. When one of their eggs rolls out of the nest, the mother goose will go out and, with her head, basically roll the egg back into the nest. Now, this is what we would call an innate behavior. The goose just does this automatically, and in terms of what causes this behavior, well, it's the stimulus of seeing the egg outside of the nest. And in fact, you can trick a goose by putting something, that they'll think is an egg, it's not actually their egg, but you can fool them into thinking it's their egg, and they'll exhibit this behavior. Now, how did this develop? You know, did this come from dinosaurs, for example? You know, birds did evolve from dinosaurs. Maybe this was a behavior that dinosaurs exhibited, and that's why these geese are showing it. It's like genetically programmed in them from long ago in their ancestors. I mean, I'm just hypothesizing here, but that would sort of be the question of how did this behavior develop. Now, in terms of how does this behavior affect fitness, it should be fairly apparent that if the goose returns the egg to the nest, that egg is going to have a higher chance of survival, meaning more offspring. So, behavior like this will obviously increase fitness because it will lead to a higher rate of offspring reaching viability.

In terms of how did it evolve, what pressures led to this, it could have been a variety of things, but perhaps it was something like the nature of the nests caused eggs to fall out regularly or something as simple and seemingly silly as that. Now, I said that this was an innate behavior, and behaviors actually run on a spectrum from learned to innate. And innate behaviors are genetically programmed. They are going to just happen automatically, though it should be noted that some innate behaviors will require an organism to learn aspects of it, or fine-tune aspects of it, and that's why it's better to think of behaviors as existing on a spectrum from learned to innate rather than existing in these two clearly defined categories. Now a great example of an innate behavior is yawning. And you can see that this behavior has very little variation between the organisms that exhibit it, and we actually would call that a fixed action pattern. Now some fixed action patterns will be the result of an external cue, which we'll call a sign stimulus. Now obviously, yawning is going to come from internal cues. However, I'm suspicious that yawning is contagious. I don't know if you've ever experienced that, I certainly have. However, in a more serious sense, a fixed action pattern that is elicited by a sign stimulus is going to be something like the behavior of the male stickleback fish.

Now, these fish will, they have red bellies, the males have red bellies, the females don't. So here you can see a male, this is a female, no red belly, and the males have this fixed action pattern of attacking anything they see that has a red belly. And the red belly, we know to be the sign stimulus because you can put an object that looks just like the male fish in there, but without the red belly on it, it's not going to respond to it at all. You could also put an object just like this that doesn't look anything like a fish, but has that redness to it, and the male stickleback will attack it. So that is an example of a sign stimulus, this red belly, and it's going to elicit that fixed action pattern of the fish attacking it. With that, let's go ahead and flip the page.

Learning and Communication

Learning involves the acquisition or modification of behavior, which results from experience. Learned behaviors typically involve some type of choice and a cost-benefit analysis associated with that choice. Now, spatial learning is a special type of learning that establishes a spatial memory of the organism's environment, sometimes referred to as a cognitive map—a mental representation of spatial information that usually involves the relative space between objects. An excellent example of spatial learning can be seen in a water maze. Here, you place a mouse in the maze, give it a landmark, and include a hidden platform in the water. Initially, the mouse swims around until it locates the platform. However, once it learns the platform's location relative to the visual landmark, it will swim directly to the platform the next time, thanks to its spatial memory or its cognitive map.

Another special type of learning is imprinting, a time in an animal's life when it learns the characteristics of a stimulus. Often, this is seen as a child imprinting on its parent, learning the stimuli—appearance, smell, sound—associated with that parent. This usually only occurs during what is known as a sensitive period, typically at a very young age for the organism. The result is that the child recognizes its parent by certain stimuli. For example, ducklings will follow the mother duck because they have imprinted on her. However, imprinting sometimes occurs in unexpected ways, such as ducklings imprinting on humans or even inanimate objects, which demonstrates this system's potential to malfunction.

Communication involves the transmission and reception of signals between animals and can involve various kinds of signals, not limited to chemical ones. Examples include visual, auditory, and olfactory signals like smells. One fascinating aspect of animal communication is the stimulus-response chain, evident in fruit fly courtship behavior. Each signal sent by an organism serves as the stimulus for the next response by the other organism, culminating in behaviors such as mating.

It's important to note that not all communication is direct or honest. Some communications are intentionally deceitful, aimed at misleading another organism. An example is possums playing dead—a deceitful form of communication. However, deceitful communication tends to be most effective within a species rather than between different species. This phenomenon can be seen in various humorous aspects of animal behavior, notably in certain mating behaviors. For instance, some males may appear tough and dominant to ward off competition, while others may adopt deceptive strategies, such as mimicking female traits to approach a potential mate without being noticed by the dominant male.

All right. With that, let's go ahead and flip the page.

Foraging

Foraging is the term for food-seeking behaviors, and these can include searching for food, identifying food, capturing food, and actually eating the food. So it's quite a comprehensive umbrella term for basically all things food-related. Now I want to give you an example of a very interesting genetic mechanism that controls some foraging behavior, and this involves, it's kind of gross, but fruit fly larvae. Now, they're going to have this gene called ₄, for forage, and this is going to control their foraging behavior. There's going to be 2 alleles for this gene. For _r, which is the rover allele as it's called, and for _s, which is the sitter allele. The way this gene controls behavior is that rovers, as they're termed, individuals with these alleles will travel twice the distance for food as sitters will. And you can see a model of that here, the rovers are going to move around a lot further than the sitters will. Now, in terms of natural selection, low population densities will actually favor the _4s gene, because in low population densities you don't need to bother expending this much energy to find your food. However, rovers will do better in other situations. For example, in certain high-density population situations, foraging further will actually potentially lead to greater success in finding food because of all the competition with the other organisms.

The optimal foraging model basically says that natural selection favors foraging behavior that aims to minimize costs and maximize benefits. We're going to see organisms perform their foraging in this way. Food is going to be such a strong factor in natural selection because it's so essential to survival. So behaviors surrounding obtaining food are going to be heavily shaped by natural selection, and thus we're really going to see these patterns that optimize the foraging behaviors of organisms, allowing them to minimize their costs and maximize their benefits, and that's what this graph here is trying to represent. E is for energy, so we want to maximize the energy we obtain, and for the amount of, you know, expenditure we have to do in terms of finding that food. So that's going to involve putting yourself at risk, and actually expending energy to find the food. Like if you're a predator and you have to run, and jump, and bite this animal in the neck several times before you get to eat. So there's always really going to be this risk/reward balance between energy expenditure and energy gain for organisms. And it should be noted that predation is going to pose a great risk for a lot of animals when they're foraging, and it's going to influence their behavior. For example, there are this type of deer, mule deer. Now, you know, deer, they're like the rats of the woods. They just go eat vegetation and stuff just everywhere, and they can really eat, you know, vegetation wherever they want. They could eat it in the forest, they could eat it at the edge of the forest, but they tend to eat it in the edges because of the influence of predation. These mule deer are at a far lower risk of being eaten by mountain lions when they're on the edges of the forest, as opposed to when they're in the forest. So even though there's food in all of these places, they're actually going to selectively forage in those edge environments. The main point to take away here is that animals are always going to maximize their feeding efficiency and balance their risk, involving the risk of injury, the risk of predation, and the risk of wasting a bunch of energy, to get the optimal result.

Mating and Parental Care

Mating behaviors include attracting mates, competing for mates, and caring for offspring. Mating systems describe the way in which mating and sexual behavior is structured. Two examples of this are monogamy and polygamy. You can see an example of monogamy right here with these albatrosses, where one male mates with one female and they stick together. Polygamy, on the other hand, is when an individual of one sex will mate with many individuals of the opposite sex, and this can go both ways. This could be a male mating with many females, or a female mating with many males. Now, sexual selection is the type of natural selection in which members of one sex choose mates. This can involve one sex choosing a mate of the opposite sex. For example, what you see here in this mating display put on by this bird of paradise where this very plain-looking female is basically going to see whether or not she's impressed with this dude's performance, and choose whether or not she wants to mate with him. Now, this can also take the form of competition between members of the same sex. For example, rams, you know, which will smash heads to compete for who gets to mate. Now, females tend to choose their mates when they are the ones doing the choosing, based on signs of fitness and health. Now, even though this bird's dance and its feathers might not seem like obvious signs of fitness and health, the plumage color and its ability to perform those types of precise movements can actually be indicators, in an indirect sense, of this animal's health and fitness. Now, mate choice copying is an interesting phenomenon seen sometimes, where individuals in a population are more likely to mate with an individual who has previously mated. So, for example, you'll see this in certain species like guppies, where if a female witnesses a male mate with another female, that female that watched them, although it might sound kind of creepy, is going to then be more likely to mate with that male, and that is an example of mate choice copying. Now, parental care is important because it can help improve the chances of raising viable offspring. Males actually will tend to help with parental care in species that require a lot of attention and help feeding. The certainty of paternity, that is, how certain the male is that those offspring are his offspring, seems to have an effect on male parental care. And you'll actually see higher rates of male parental care in species with external fertilization because the males, it's thought, have a greater certainty of paternity because they'll go right up to the eggs and fertilize them right there. As opposed to internal fertilization where some other organism could have internally fertilized this organism, and it could be its offspring, you just, it's harder to know. So here you see an example of some parental care where these little chicks, kind of gross-looking chicks, to be honest, are going to get fed by the parent here. And of course, here you can see a wonderful example of human parental care, which is paternal care. Alright. Let's flip the page.

Migration and Altruism

Animals will generally choose where to live based on food and mates. Some organisms will actually, in their lifetime, move very great distances, and this is known as migration. This is a long-distance movement of a population, and it's usually associated with seasonal changes. However, organisms will migrate for a variety of reasons, like the availability of food sources, differences in climate, or for mating purposes. Now we'll actually see 3 interesting types of migration, what we call piloting, which is basically the use of familiar landmarks to find their way: compass orientation, where the organisms have their movement oriented to a specific direction, and true navigation, which is the ability of animals to find their way as if they were looking at a map, like as if they had GPS or something. One example of this is with sea turtles that have the ability to sense the magnetic field of the Earth and use that sense of the magnetic field to orient themselves. Basically, you know, blindfold a sea turtle, drive it around, take it in a bunch of back streets for a while, throw it in the ocean, and it'll still find its way because it has that ability of true navigation. And here you can see a herd of wildebeests migrating, and here you can see some migratory patterns of birds, and hopefully you realize how astounding some of these distances are that these birds will travel.

Altruism is an interesting type of behavior because it seems counterintuitive in some ways. It's a behavior that actually has a fitness cost to the actor that exhibits it. So the organism that exhibits the behavior receives a fitness cost, meaning there's a detriment to their fitness, and the recipient of this behavior will actually receive a fitness benefit. So, why would an organism do this if it's not seemingly in its own self-interest? Well, part of the explanation for this is something known as kin selection, which is an evolutionary strategy that favors the reproductive success of an organism's relatives. And you can see this in organisms like bees, for example. Now, Hamilton's rule is a way of looking at altruistic behavior, and it basically says that when certain conditions are met, you're more likely to have an altruistic behavior. These conditions are that the benefit to the recipient is going to be high, the cost to the actor is going to be low, and it's also going to factor in something known as the coefficient of relatedness, which is the average number of genes that are shared between the individuals.

This is represented with the equation: r > c b where: r is the coefficient of relatedness, c is the cost, b is the benefit. The idea is that the benefit is high enough, and the coefficient of relatedness is high enough that it outweighs the cost to the actor.

So, if you're still wondering why we would see this type of behavior, why we'd see altruism, Hamilton developed this idea. It's sort of a different way of looking at fitness, and he calls it inclusive fitness. This is basically a way of looking at fitness where you're looking at the evolutionary success of an organism based on the number of offspring it produces, which is pretty standard in how we look at fitness, but it also includes how that individual helps its relatives produce more offspring than they otherwise would be able to on their own. It's believed that these behaviors are seen because they might not directly spread an organism's genetics, but because it's happening with relatives, those relatives are going to share a portion of that organism's genes, and so the organism is helping to pass on a portion of its own genes by helping its relatives, though it's not directly passing on all of its genes.

Now an interesting idea that has sort of been extrapolated from this thinking is the idea of reciprocal altruism. This is going to be seen between organisms that are not related. This is when an actor is going to temporarily reduce its fitness to benefit the recipient, under the assumption that the recipient will return the favor someday. This is seen, for example, in communities of chimpanzees. It's thought to explain some aspects of human behavior and altruism amongst humans.

One nice example that I want to leave you with of all this altruism, all of this thinking is with prairie dogs. Prairie dogs are numerous, they live in big communities with lots of relatives, and prairie dogs exhibit this behavior you see here, where they kind of like scream, basically, to alert their community of the presence of a predator. I don't know if you can tell, but there are some feathers back here. Prairie dogs have to watch out for birds of prey, which love to eat them. So this is an example of altruistic behavior because by alerting their community, by making this noise, these prairie dogs actually draw attention to themselves. So they put themselves at a greater risk of predation, but it helps warn all their brothers, and so that means their brothers are more likely to survive, and this is going to help with their inclusive fitness. That's all I have for this one. See you guys next time.

Here’s what students ask on this topic:

What is the difference between proximate and ultimate causation in animal behavior?

Proximate causation refers to the immediate, mechanistic reasons behind a behavior. It looks at how behaviors occur, focusing on genetic, neurological, and physiological factors. For example, it might explore what genetic factors trigger a goose to roll an egg back into its nest. Ultimate causation, on the other hand, examines why a behavior occurs from an evolutionary perspective. It considers the function of the behavior and how it affects an organism's fitness and survival. For instance, ultimate causation would explore why the egg-rolling behavior evolved and how it benefits the goose's reproductive success.

How does the optimal foraging model explain animal behavior?

The optimal foraging model suggests that natural selection favors foraging behaviors that maximize energy gain while minimizing costs. This model posits that animals will adopt strategies that provide the most food for the least amount of effort and risk. For example, mule deer prefer to forage at the edges of forests rather than deep inside, as this reduces their risk of predation by mountain lions. The model helps explain why animals make certain choices about where and how to find food, balancing the energy they expend with the energy they gain.

What is imprinting in animal behavior, and when does it occur?

Imprinting is a type of learning that occurs during a specific, sensitive period in an animal's life, usually at a young age. During this time, the animal learns the characteristics of a particular stimulus, often a parent. For example, ducklings imprint on their mother, learning her appearance, smell, and sounds, which helps them follow her for protection and guidance. Imprinting is crucial for survival, as it ensures that young animals stay close to their parents, who provide care and protection.

What are the different types of mating systems in animals?

Mating systems in animals describe how mating and sexual behavior are structured. Two common types are monogamy and polygamy. Monogamy involves one male and one female forming a pair bond, often for a long period, as seen in albatrosses. Polygamy involves an individual of one sex mating with multiple individuals of the opposite sex. This can be further divided into polygyny (one male, many females) and polyandry (one female, many males). These systems are influenced by factors like parental care, mate availability, and the need to maximize reproductive success.

What is altruism in animal behavior, and how is it explained by inclusive fitness?

Altruism in animal behavior refers to actions that benefit another organism at a cost to the actor's fitness. Inclusive fitness explains this by considering not just the individual's direct reproductive success but also the success of its relatives. By helping relatives, an organism ensures that shared genes are passed on. For example, prairie dogs alert their community to predators, increasing their own risk but helping relatives survive. This behavior is favored by natural selection because it enhances the overall genetic success of the family group.