A protein similar to the mammalian hormone prolactin is found in amphibians and birds. In amphibians, such as newts, it causes the animals to seek water as they do when they lay their eggs. In birds, such as pigeons, it causes them to regurgitate material from the crop to feed their young. Mammals respond to prolactin by producing milk. How does the theory of common descent explain these similarities?
This is for my lab so it does matter, religon people leave no comment.
When I say religion people no comment im not insulting them i have my religious beliefs, i just strictly wanted a science answers
It shows that once natural selection comes up with something that works, it is often reused for other purposes.
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Long time since I had Bio, but I think it has to do with keeping the species alive.
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Common decent would explain this because this protein is still present in all of these animals even though they are so different. The protein was only developed once and then passed down for thousands of years until they ended up in the animals we see today.
For the non evolutionist that answered previously, it’s great that you don’t believe in it, but don’t tell someone else what they believe is wrong. Besides, it’s for school and we learn alot in school that we may not believe in, so just because he has to answer the question doesn’t mean he deserves your criticism.
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In reality there is a lot of variance in the varieties of prolactin. There was a common gene. And there was divergence from that common gene about 400 million years ago. The key is parental care. The common link is parental care.
The following paper is very good. However, it is complicated.
Prolactin: Structure, Function, and Regulation of Secretion
http://physrev.physiology.org/cgi/content/full/80/4/1523
Based on its genetic, structural, binding and functional properties, prolactin belongs to the prolactin/growth hormone/placental lactogen family [group I of the helix bundle protein hormones (195, 791)]. Genes encoding prolactin, growth hormone, and placental lactogen evolved from a common ancestral gene by gene duplication (1311). The divergence of the prolactin and growth hormone lineages occurred ~400 million years ago (357, 358). In the human genome, a single gene, found on chromosome 6, encodes prolactin (1363).
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This is known as a ‘homologous protein.’ (It’s worth googling.) Just like a homologous structure, a homologous protein is something shared between two or more species that serves a different function in each.
The theory of common descent explains homologs as structures that arise in some ancestor, and find different functions in descendants. In other words, there is not a one-to-one corrrespondence between a protein and its function in all organisms. Life reuses material it already has … and so if it has a protein used for function A, if that function is no longer needed (as when a branches of amphibians evolved into something that does not need to seek water) then that protein is now free to be adapted to serve function B in one branch, and function C in the other.
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