The chicken and the egg...

[Externet]

Or better said, the hen and the egg.

 

All living creatures go to a great extent in conserving energy, finding food and not wasting resources is an activity that takes most of their time.

 

Non-fertile eggs laid by hens are a huge waste of resources, food and energy. Is there an explanation, please ?

[CharonY]

A zoologist would provide a better response but essentially birds also undergo ovulation cycles. In addition, after mating many (most?) birds are able to store sperm for an extended period of time, which can be used to fertilize said eggs. I expect that under natural conditions the mating rate is very high and thus the occasional loss due to unfertilized eggs is relatively low. The high production breeds used for egg production are the result of artificial selection of course, in nature they do not lay that many eggs.

[Sisyphus]

The chicken has been selectively bred for egg production for thousands of years. So, as with all traits artificially selected for, the "evolutionary advantage" of producing a lot of eggs, fertile or not, is that humans will allow it to breed. Hardly a waste! The egg has gained another function - pleasing humans - in addition to its original one of transmitting genetic material and nourishing offspring. It's similar to a natural symbiotic relationship, except that it can happen a lot faster if it is deliberately rather than statistically selected for.

[JN.]

Fertile eggs would be chosen by Natural Selection, but hens have been chosen by artificial selection. The characteristics "chosen" by natural selection are those who allow animals to breed more than their partners in a wild state; when we're speaking about artificial selection, the characteristics that matter are those more favorable to the selector. 

 

The evolution of dogs or cattle are also similar: their characteristics would not allow them to survive in a wild state, but are favorable to men.

 

 

[eleven]

I would imagine a baby chicken.

It would be better said, what came first, the embreo or the sperm?

I'd say sperm - therefore I believe a baby chicken came first. A budding creation - seeing as an egg needs to grow as well. Maybe a baby egg. I can't answer the question >:[

[Mr Skeptic]

I can't answer the question >:[

 

Then I suggest you try reading the question first. I too have great difficulty answering a question I haven't read.

[marmer]

Although not absolutely sticking to the question I find it interesting to comment the following related theme.

Very occasionally a chick from a non-fertilized egg is born to a female virgin bird (or at least I have heard so). This is called I belive parthenogenesis, the development of an embryo out of a non fertilized egg.

It happens quite often in the most ancient lines of animals but to the best of my knowledge the last two groups of animals to evolve, birds and mammals, virtually never reproduce by this system, birds very occasionally, mammals, never.

Has anyone ever heard of a mammal who truly produced a clone of itself?

In the past, if this might have ever happened it would have been impossible to ascertain (poor of any woman who would have suffered such an event!). But nowadays it is simple and clear to check any suspicious case and find out the truth.

In my opinion there is an interesting question pending a good answer. Why mammals have lost completely the ability to produce clones of themselves when the absolute majority of the rest of the living world (plants, fungi, other animals, microorganisms) can do so?.

[Leader Bee]

Sorry, are we to presume that mammals once did produce clones of themselves (do you mean Asexual reproduction?) or do you have some evidence that this was previously the case?

[AzurePhoenix]

Mammals have always been male/female, derived from similarly sexed ancestors, and even though parthenogenesis happens in other vertebrates occasionally, birds (particularly domestic turkeys,) sharks, lizards (such as komodo dragons, but particularly in a hybrid-descended all-female species of whip-tail lizard) etc, mammals have never been known to reproduce parthenogenesically in nature. It's complicated in mammals by genomic imprinting, which is where only alleles inherited from the mother are expressed for certain traits, and only alleles from the father are expressed for others. With only a set of maternally-inherited alleles, expression is incomplete, and when parthenogenesis is artificially induced in mammals in the lab, developmental issues ensue.

[Ninjakat]

Although not absolutely sticking to the question I find it interesting to comment the following related theme.

Very occasionally a chick from a non-fertilized egg is born to a female virgin bird (or at least I have heard so). This is called I belive parthenogenesis, the development of an embryo out of a non fertilized egg.

It happens quite often in the most ancient lines of animals but to the best of my knowledge the last two groups of animals to evolve, birds and mammals, virtually never reproduce by this system, birds very occasionally, mammals, never.

Has anyone ever heard of a mammal who truly produced a clone of itself?

In the past, if this might have ever happened it would have been impossible to ascertain (poor of any woman who would have suffered such an event!). But nowadays it is simple and clear to check any suspicious case and find out the truth.

In my opinion there is an interesting question pending a good answer. Why mammals have lost completely the ability to produce clones of themselves when the absolute majority of the rest of the living world (plants, fungi, other animals, microorganisms) can do so?.

 

Sorry if im going to far back here, but there was a komodo dragon in the british zoo in england where it produced a baby asexually. Its very interesting how similar birds and reptiles are.. In a book I have there are theories they are related to eachother. I wonder how one sprouted wings, whilst the other had scales/skin.

[Moontanman]

Sorry if im going to far back here, but there was a komodo dragon in the british zoo in england where it produced a baby asexually. Its very interesting how similar birds and reptiles are.. In a book I have there are theories they are related to eachother. I wonder how one sprouted wings, whilst the other had scales/skin.

 

 

This is off topic but there are many threads on this forum that explain that very thing, check them out....