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Psychology: Animal Behaviors – Follow- up Assignment

1. One of the concepts that we'll discuss this week is an "honest signal". Honest signals convey accurate information about the sender's quality. These signals are honest because they cannot be faked.  A classic example of an honest signal is the  peacock's tail feathers . Only a strong and healthy male can produce a fabulous display, so female peacocks can rely on this signal when selecting a mate.  Similarly, an antelope that jumps 10 feet into the air is an agile antelope, and a cheetah can rely on this signal when selecting prey.  In humans, honest signals would be characteristics (or possessions) that relay generally accurate information about the sender's fertility, wealth, power etc. For this weeks forum, discuss an honest signal that humans use (describe the signal, explain it's meaning, discuss why it's honest) Three things to keep in mind:  (1) Intentions are irrelevant.  In this class, we are interested in actions, not intentions.  When you consider honest signals in humans, you don't need to limit yourself to intentional signals.  (2) The key characteristic of honest signals is that they can't easily be faked. (Before you suggest a particular aspect of body language as an honest signal, consider whether it can be faked.) (3) You can use signals that were reliable over much of human history as well as signals that are new.

As an example of a previously reliable signal, consider white teeth. White teeth used to be an honest signal of youth and health, and we are attracted to youth because it is correlated with fertility and we are attracted to health because it is correlated with good genes and a lack of contagious diseases.  Of course, nowadays we can whiten our teeth, so this is no longer an honest signal, but we still find white teeth attractive.  You can use an example like this if you can explain why it used to be an honest signal. As an example of a currently reliable signal, consider owning a Porsche. Only the very wealthy can afford them, so a Porsche is a pretty reliable signal that the owner has resources.

Comment :  These posts need to be in your own words. When you write something like, "This paper seeks to explain signals cues and meaning", I think you may be relying too heavily on a paper for the material in your post. Other clues are the smattering of jargon and the uneven nature of the writing. 

Read the questions and comment. Write a response (200 words)

2. Animals use variety of  sensory "channels" to communicate, including the visual channel, the auditory channel, the  tactile (touch)  channel, and the  odor  channel. What are advantages/disadvantages of each channel?  That is, explain why a particular channel would be more advantageous in a particular situation or for a particular kind of message. Consider: The environment  (air, water, underground, in the jungle, in open ground, daytime, nighttime) The message (should it be public or private: should it travel far and wide, or should it be local? Should it last awhile or be very brief?) Note: The background material might give you some ideas, but I think you can answer this question just by thinking about it. 

Remember: Your task is to come up with one new idea, ideally with an example.  There are many channels and many reasons why each one works best in a particular situation, so if you ponder this a bit you will find something new to say. But don't write an essay that attempts to cover everything because that will make it more difficult for your classmates to come up with something new.

Read the question and use your own word, and no cite, write a response (100-200words)

3. The moth/bat video introduced the concept of Batesian mimics. A Batesian mimic species copies the honest signal of another species, called the model. For example, one butterfly species that is not poisonous may mimic the coloration of another butterfly species that is. When birds taste the poisonous model they will learn to avoid it, and they will also avoid the mimic. How does the mimic species affect the fitness of the model species? What will happen if the mimic species is more numerous than the model species?

https://www.smithsonianchannel.com/videos/why-is-this-lizard-doing-push-ups/50029

https://www.youtube.com/watch?v=qr5Sru8gGSk

https://www.youtube.com/watch?v=psnvOqtRmzI

https://www.youtube.com/watch?v=NeCmSL_N65A

https://www.youtube.com/watch?v=irkYP8vxVzE

https://www.youtube.com/watch?v=RpywSqvXDqc

https://www.youtube.com/watch?v=vLb0iuTVzW0

https://www.youtube.com/watch?v=WnNvkGEdofQ

https://www.youtube.com/watch?v=8c7NEf6qFlc

Read the question and video , use your own word, and no cite, write the answer.

4. The Introductory Discussion for week 3 asked for your intuitions on whether altruism can be reconciled with natural selection.  Your posts were invariably thoughtful, and I gained some insight into your thinking. Those posts, along with the answers to the Checkpoint Question, suggest that I need to better explain why scientists believe that animals do not behave for the “good of their species”. Here's a bare bones explanation. Natural selection says that:  Behaviors that are inherited and that increase reproductive success will become common in the population. If an inherited behavior does impedes reproductive success, then it will become less common in a population (and eventually disappear). This very simple idea needs just one addition: because you share your genes with your relatives, if your behavior helps your relatives reproduce, then it can become common in the population. In contrast, if an animal behaves in a way that increases the fitness of others at the expense of its own fitness (and that of its relatives), then its genes will not be passed down. A longer explanation with an example:  As we all know, if an inherited trait improves reproductive success it will become more common in the population. (Recall the rock pocket mice living on lava flows. The mice with dark coats, an inherited trait, outcompete the mice with light coats and the dark mice eventually become more prevalent.) This, of course, is “natural selection”. Let’s apply this same logic to altruistic behaviors that are for the good of the species. We'll examine a specific behavior,  lemming “suicide”.   Lemmings are small rodents found near the arctic.  They live in colonies and multiply quickly.  Sometimes a lemming colony outgrows its food source and groups will split off the colony and migrate elsewhere.  People have observed these migrating lemmings drowning in rivers or running off cliffs.  From these observations, it was concluded that some lemmings act altruistically,  “committing suicide” to benefit their species as a whole.     Can nature select a behavior that benefits the species rather than the individual and its relatives? No!   This altruistic behavior, like all behaviors, arises from the interaction of genes and the environment.  All genes are susceptible to mutations.  Eventually, one of the genes involved in this “suicidal” altruistic behavior will have a mutation that impairs this behavior.  The lemming with this mutation will not be inclined to commit suicide. Instead it will stay behind and reproduce (or migrate and try to find a better home). Over time what would you expect to happen? This non-suicidal behavior will increase reproductive success, and eventually the suicidal behavior will be eliminated from the lemming population.  The point is that when an animal reduces its fitness for the good of the species, it simultaneously eliminates its genes from the species' gene pool. Therefore, Natural selection automatically wipes out behaviors that benefit the species rather than the individual or the individual's relatives.   

Which of these lemmings has the highest fitness? If lemmings aren't committing suicide, why are they jumping into rivers or off cliffs?    The lemmings migrate when food has become scarce.  So hunger may drive them to leave to find a new territory with more resources. During their migration they may encounter physical barriers (swollen rivers, unstable cliffs) that end up being deadly. The logic of natural selection suggests that even though this migratory behavior is risky, it is better than the alternative. In other words, despite the risks, migratory lemmings must survive often enough that this behavior increases their fitness relative to staying behind and not migrating.  (If you’re wondering why not all lemmings migrate, it’s a good question. We'll get to that later.)  

It's critical that you understand why natural selection would eliminate behaviors that are “for the good of the species”. If you do not understand, please let me know what part of this explanation seems suspicious or confusing or just plain wrong. I will follow up with you in an email. You will earn full points if you are willing to go over this with me. If you do understand why natural selection would eliminate "good for the species" behaviors, rewrite your answer for the week 3 checkpoint question.  If you thought answer #2 is inconsistent with natural selection, revisit the concept of indirect fitness and the week 3 article on scrub jays.  If you thought answer #1 is inconsistent, it might have been a misunderstanding. When I wrote,  "the non-breeding adults need to stay with the pack to survive"  I did not mean that these wolves were inferior to wolves who can go it alone. All wolves need to be part of a pack because their hunting strategy  requires teamwork.   Because I've  told you the answer, I will grade your do-over on your explanation for why your previous answer was incorrect and why answer #3 is correct.

By doing this assignment, you can earn back any points you missed.   Here's the original question: In wolf packs, only the alpha male and alpha female mate. The other adults forgo breeding and help raise the young. Consider three explanations for this behavior:  1) The non-breeding adults need to stay with the pack to survive, and eventually they may become the alpha members. 2) The non-breeding adults are helping raise their siblings. 3) The non-breeding adults are less fit than the alpha pair, and they are foregoing reproduction for the good of the species. Which one is inconsistent with natural selection? Maybe the misunderstanding is due to the wording.  "Inconsistent" means "against" or "contrary to". So I could have said, "Which one does not fit with natural selection?" "Species" means all wolves (not just the pack). The answer is #3. This explanation is contrary to natural selection. #1 fits with natural selection. The non-breeding adults are increasing their fitness by staying with the pack since they wouldn't survive otherwise.  Eventually, they may work their way up the wolf hierarchy and become the alpha members.  In other words, staying with the group and waiting your turn to reproduce is a much better strategy than trying to go it alone and likely dying.  This behavior can increase reproductive success and become common in the population. #2 fits with natural selection. If the non-breeding adults are related to the rest of the pack, they can improve their indirect fitness by assisting in raising their relatives. They will pass the genes for this assisting behavior through their relatives, who share their genes. This behavior can increase reproductive success (via indirect fitness) and become common in the population. The answer: #3 does not fit with natural selection. If the non breeding adults are acting for the good of the species by not reproducing, their genes will be wiped out. This is like lemming suicide: the genes involved in this behavior are not passed down.   This behavior does not increase reproductive success and so it will not persist over generations.

What I answer: No for all. This is because not only does the best pair of wolves in the pack get to extend their superior genes for continuity of the pack, those wolves in the pack that are perceived weak and a threat to the continuity of the pack are either chased out or made to be servants for the rest of their existence. This works in a huge way to preserve such strong traits for many generations to come.

What you need to do is Because I've  told you the answer, I will grade your do-over on your explanation for why your previous answer was incorrect and why answer #3 is correct.