Fish and The Extended Phenotype

[ewurm]

I have great interest in how genetics plays a role in behavior. The extended phenotype theory suggests that genes not only code for internal structures, but they also code for external structures in the environment in which a species is found. For example, the genes of a beaver not only code for the entire structure of the beaver itself, but they also code for making beaver dams. We like to think that beavers build dams. In actuality, it's genes that build the dams in order to alter the environment to be better suited for those genes. The beaver is a tool that the genes use to reproduce themselves. Natural selection not only affects species and individual creatures, but also the environment.

An ichthyological example in fish would be the building of a nest. The sunfish in the example below are clearing out a nesting area in order to make the area more suitable for their eggs, specifically providing a rockier depression so that the eggs will not be washed away or buried in detritus. The proximity of the nests probably provides strength in numbers.

The next time your cichlids start moving around your plants and gravel, you'll know the driving force behind the behavior.

 

[ewurm]

No fans of genetics?

 

[joe jaskot]

How do you know that it is genetic and not a learned behavior? Would human beings know how to reproduce without learning how?

 

[andyjs]

How do you know that it is genetic and not a learned behavior? Would human beings know how to reproduce without learning how?

Learning may have a small part in this behavior, but I would be willing to bet that if a baby cichlid/sunfish were removed from a nest before it even hatched and then raised, it would still instinctually know how to build a nest when the time came despite never having a chance to learn from its parents. And as far as humans go, yes. As far as rearing a child, we have gotten better at it through cultural learning across our society. As far as....making a child, it's a pretty natural behavior

 

[joe jaskot]

Learning may have a small part in this behavior, but I would be willing to bet that if a baby cichlid/sunfish were removed from a nest before it even hatched and then raised, it would still instinctually know how to build a nest when the time came despite never having a chance to learn from its parents. And as far as humans go, yes. As far as rearing a child, we have gotten better at it through cultural learning across our society. As far as....making a child, it's a pretty natural behavior

So basically, if you isolated a male and female human being from the time of birth, they would know how to reproduce? Then why do they bother teaching sex education in health class? LOL!

 

[Theseabean]

Ive heard of this theory before, I read about it occurring in some fish in Guyana when I was studying fish there. I do, however, think its a stretch to say that genetics codes for not only favorability in traits but also in behavior. But I could so how it would make sense. Blue-gray tanagers and palm tanagers are oscine, birds, they learn their own songs, and chicks separated at birth will still hybridize in captivity, even though they are free of environmental factors including stress, unlike their parents which also hybridize in the wild. They do it because of female preference in mate selection, so it makes sense in that respect but doesn't make sense in that there is no biological reason for them too. Yet they do it even after generations in captivity.

 

[KristaM92]

I never watched my parents have sex when I was little, yet I figured out how later in life. Genetics wins this one.

In all honesty though, that's a really neat genetic theory. It's strange to think of our bodies as vehicles for genes.

 

[vitaly]

i think there was a study on some sort of similar species of birds (finches maybe?). one specie carried twigs with their feet to build a nest, the other specie carried them with their beak.
when these two where hybridized in captivity, the hybrid birds could not figure out how to build a nest. they've tried both ways but just could not figure it out.

Also, i think humans do have programmed behavior. it has been said that pregnant women always go shopping right before giving birth (they need materials to build a nest)

 

[ewurm]

Learning may have a small part in this behavior, but I would be willing to bet that if a baby cichlid/sunfish were removed from a nest before it even hatched and then raised, it would still instinctually know how to build a nest when the time came despite never having a chance to learn from its parents. And as far as humans go, yes. As far as rearing a child, we have gotten better at it through cultural learning across our society. As far as....making a child, it's a pretty natural behavior

I've had captive bred cichlids that were removed as fry build a nest and successfully reproduce.

 

[ewurm]

Caveat: I'm only saying that genetics codes for basic instinctual behaviors. The knowledge of particle physics cannot be coded into DNA. At least it looks that way.