How can a behavior be a phenotype?

Question

If a behavior is a phenotype, then wouldn't that also mean that there is a genotype for the behavior? If there is a genotype for that behavior then wouldn't that also mean that a allele is present on either or both chromosome inherited by the parents. Is there such a thing as a behavior allele? How can one tell the difference between what is the factoring result of mental characteristic, and the result of a genetics?

Answer 1

For humans and so-called "higher animals", behavior is certainly more complex than genetic factors (which ARE the main source of invertebrate and prehaps other animals' behavior). However, there ARE many physiological influences on behavior. A common example would be depression. A main source of depressive symptoms is a chemical imbalance in the brain. However, it must also be remembered that these imbalances only trigger depression with outside influences (ie, from the environment). It is this interplay between genetic predispositions and environmental/personal factors that causes much of behavior. Of course, the critical element is what an individual chooses to act upon, and that is why there is no way murderers etc. can simply blame either their genetics or their environment, but these two factors do play a big role in setting you up for what type of person you may be (that is, how you may act in a given situation). For another example, when an identical twin has schizophrenia, the other twin has a 50% chance of developing it as well. This increased chance clearly shows genetic influence, but the fact that it is not 100% (which would be expected if schizophrenia were determined by genetics alone) shows the environment and individual behavior is important as well.



So, simply, there ARE genetic predispositions to behavior, but they are just that- behavior is fundamentally under the control of the brain.



PS- You cannot tell very well how much the environment, genetics, and individual differences factor into behavior. so therefore it is important to remember that all three play a critical role together.

Answer 2

Wikipedia is right. A behavior can be a phenotype. A phenotype is anything that is observable (E.g. color, size) and that certainly includes behavior.



That does not mean all behaviors will have a simple genetic cause, but some will. For instance, Tay Sachs Disease has a simple underlying genetic cause. In one form of the disease (juvenile TSD) the afflicted person develops cognitive, motor, speech difficulties (dysarthria), swallowing difficulties (dysphagia), unsteadiness of gait (ataxia), and spasticity.



These are all behaviors and they are all part of the phenotype of this disease.



Also, a phenotype can originate from a gene on any chromosome. A phenotype can also originate from the interplay of multiple genes that may be on different chromosomes. In the case of Tay Sachs, the phenotype is caused by a mutation on Chromosome 15.



SECOND UPDATE - if you read the link I provided below you will see that I am right.



Yes, they are symptoms of the disease, but it is still a phenotype because this is a genetic disease. Tay Sachs Disease is not like a virus or a flu, it is caused by a person's genotype. The symptoms of the disease are therefore a phenotype.



In juvenile Tay Sachs Disease the afflicted person develops cognitive, motor, speech difficulties (dysarthria), swallowing difficulties (dysphagia), unsteadiness of gait (ataxia), and spasticity.



All of those things are behaviors.

All of those things are observable. By definition that makes them a phenotype.

And, they are all caused by the Tay Sachs Disease.



The definition of a phenotype is anything that is the observable consequence of an allele. The Wikipedia article on Phenotype is exactly right. If you don't want to believe Wikipedia, then Google "phenotypic behavior" or "behavioral phenotype" and you will find plenty of other references that talk about behavior as a phenotye.

Answer 3

The phenotype is the physical EXPRESSION of the genotype. Some phenotypes can be things like traits eg pigmentation ( colouring), present of absence of a trait eg freckles, tail, whatever....but it also for things like how a an organ produces certain chemicals or not producing them eg cystic fibrosis ( no hairs in lungs also affects something else... hmm forgotton) other diseases.

There are also characteristics as well which in some people can be seen as habits, the way someone holds their head, or other gestures that you see in other family members, some behaviours are thought to be linked to genes eg tendency to alcoholism, drug use etc

I don't think people are too sure how these behaviours are inherited ....as pointed out there is the nature vs nuture thing but how much of each is not really understood.

Answer 4

sounds a lot like the nature/nurture argument. technically, there could be genes that make you more 'prone' to certain, say, brain functions or possibly chemical imbalances that can be turned on and off by epigenes, causing behavioral changes. behavior isn't necessarily a phenotype though. your thinking is correct, if someone told me behavior was a phenotype i would question it also. good logic. if you haven't heard of nature vs nurture, it basically questions whether the way a person is is more influenced by their genetic 'dispositions' or the way they were raised. it's a huge scientific debate that's been studied for decades. personally, i think nature and nurture play equal roles. you should look into it more if you haven't. it's fascinating!

Answer 5

A phenotype is the physical result of genetic organisation (ie genotype)



Although behaviour is not physical, it results from physical characteristics in the brain -which are considered phenotypes- and can often result from genetic predisposition.

Answer 6

Phenotype is the physical characteristics expressed in alleles. It cannot not be a behaviour.



Behaviour is something that can be done emotionally rather than physically.

Answer 7

behavior is a human control. Behavior shouldn't be something that is inherited, it is something that we can control.