Colour Vision in Birds and Mammals

[goingtothedo]

A question if anyone out there can answer it for me:

 

We humans have colour vision based on three sets of different types of receptor, each sensitive to a different range of light frequencies.

 

Birds demonstrably also have colour vision. Is theirs based on the same method of detection?

 

1) If so, was theirs and ours evolved separately? Or does it go back to somewhere deep in the roots of the vertebrates? Humans, I assume lost theirs somewhere along the way when our ancestors were nocturnal "shrews", but did we lose it altogether and then have to re-eveolve it? Or did we almost lose it and then recover it?

 

2) If not, what is the bird method?

[foodchain]

Well, the question as posed is a bit dodgy, but I will try.

 

I don’t know exactly what you mean about separate evolution exactly, or maybe coevolution? As it stands birds did not just appear from nothing so to speak, separate from other life, as being decedents of the dinosaurs, or really some in particular, dinosaurs already possessed vision, as vision is not something new to dinosaurs either overall. Its pretty much the same with people too, as in what we evolved from already had vision. Bird vision is different from humans to an extent, but really I think a physiology text or article on the subject could do a better job then I can as to what the difference is and why.

 

As to the evolution aspect, well, life does offer flightless aquatic aves, that have taken on a strategy or form more suited for its ecology, which also serves a role in the physiology of such species eyes, so its probably the same I would imagine that is behind the overall physiology of bird vision in general, or vision in general.

[Paralith]

I can't speak much to the mechanism, but I have a few bits of knowledge that might answer the phylogenetic aspect. What few people know is that all reptiles (which includes birds, despite their having evolved to a very different form) have color vision. Mammals and reptiles are also sister groups. So you might think that color vision evolved in the common ancestor between reptiles and mammals. However, a great many mammals do not have color vision. Primates are one of the notable exceptions. (One theory has to do with primates being primarily frugivores - it's hard to tell when a fruit is ripe if you can't tell what color it is.) So if anything, primates probably evolved color vision independently from reptiles.

 

Birds and mammals share quite a few independently derived characteristics, such as being warm blooded. It would be interesting to think about what aspects of the two groups' evolution caused this.

[goingtothedo]

I can't speak much to the mechanism, but I have a few bits of knowledge that might answer the phylogenetic aspect. What few people know is that all reptiles (which includes birds, despite their having evolved to a very different form) have color vision. Mammals and reptiles are also sister groups. So you might think that color vision evolved in the common ancestor between reptiles and mammals. However, a great many mammals do not have color vision. Primates are one of the notable exceptions. (One theory has to do with primates being primarily frugivores - it's hard to tell when a fruit is ripe if you can't tell what color it is.) So if anything, primates probably evolved color vision independently from reptiles.

 

Birds and mammals share quite a few independently derived characteristics, such as being warm blooded. It would be interesting to think about what aspects of the two groups' evolution caused this.

 

THankyou for that

 

Yes, you've got the point of what I was trying to ask. I think I must have expressed myself badly if the previous reader thought that my question was "dodgy"

 

Yes, as you say, most mamals do not have colour vision. It is my assumption that this was an adaption during the time when our early mammalian ancestors were nocturnal shrewlike creatures. i.e. WE do no have colour vision in the dark. Below a certain light level we see in monchrome.

 

That being the case, we (the primates) must have re-evolved our colour vision.

 

Now I don't know if this was from a standing start, so that our method of colour vision is unique. Or did we perhaps "flick a (genetic) switch" back to "on" and rediscover the colour vision our reptile ancestors may have had. If that is the case, presumably we share much of the mechanism with the birds.

[foodchain]

THankyou for that

 

Yes, you've got the point of what I was trying to ask. I think I must have expressed myself badly if the previous reader thought that my question was "dodgy"

 

Yes, as you say, most mamals do not have colour vision. It is my assumption that this was an adaption during the time when our early mammalian ancestors were nocturnal shrewlike creatures. i.e. WE do no have colour vision in the dark. Below a certain light level we see in monchrome.

 

That being the case, we (the primates) must have re-evolved our colour vision.

 

Now I don't know if this was from a standing start, so that our method of colour vision is unique. Or did we perhaps "flick a (genetic) switch" back to "on" and rediscover the colour vision our reptile ancestors may have had. If that is the case, presumably we share much of the mechanism with the birds.

 

I did not mean the use of the word to imply something negative, and please excuse me if you felt that way about it. I don’t know the exact amount of vestigial structures humans hold from evolution on any particular level. I also don’t understand the degree in which one of these could be slipped back on. I know that research has basically reversed engineered some issues biologically, as in line of what I think you are talking about. The research basically involved understanding why the body had something apparently useless really, hormone and receptor I think. I don’t know what species this was performed on, but the article is out on the net, and if you want I could post it at a later date.

 

As for the exact mechanism of evolution to vision in our species, well I doubt for that to be any simple or quick answer, also for birds I would say this, or life in general. I mean in the ocean fish exist that have defense mechanisms I doubted could exist, such as basically becoming invisible to a certain extent in relation to various types of predator. The way in which the organisms achieves this at first glance seems to be somewhat right out of a sci-fi novel. When I first saw this fish do such, from the bottom up it truly did look almost invisible to my eyes. Also looking at life in the oceans, even certain depths, just the depth aspect takes on a role in evolution, such as certain offspring will basically occupy a certain depth for a period of time while developing, so in short again I don’t think a simple answer could really suffice, more so in conjunction with the other questions you asked.

[goingtothedo]

Thanks for that.

 

And don't worry about my thinking anything "negative". There's nothing clever about expressing oneselves badly. It's the job of the questioner to pose the question in a clear and coherent fashion.

[foodchain]

Thanks for that.

 

And don't worry about my thinking anything "negative". There's nothing clever about expressing oneselves badly. It's the job of the questioner to pose the question in a clear and coherent fashion.

 

Well, I could also ask a question that if our biology as a specie simply could be classified as nothing more then a collection of vestigial structures, for instance how many fingers we have and the amount of bones make them up.

 

I have a weird and I think interesting question going on in pseudoscience and speculations if you would like to participate in that one. I think your question would fit nicely in a hypothetical mode in it. For instance, our eyes would have to evolve to be able to basically discern what already exists, such as certain wavelengths of light, as to the question then is how does what constitutes life becoming able to recognize this on some level, as also to muscle mass in the earths gravity, or bone density for that matter, which would then relate back to the specie for instance a cheetah. That animal has a very light skeleton to assist its blazing land speeds.

[goingtothedo]

OK. I'll have a look at it.