How have genetics and developmental biology influenced evolutionary theory?

I think it's been wonderful for evolutionary biology. To my mind, the fusion between evolutionary biology, developmental biology (evo devo) and now ecology (eco devo) has produced new ways of understanding evolution that are on an intellectual scale comparable to the New Synthesis of the 1930s (which combined what was known about evolution with the new field of genetics). Got to go now. But will come back and see if ordinaryguy posted.

Yes, tell me more.

I read something not long ago where biologists were asked what they thought the most exciting and significant advances were in genetics in the last five years. I may not get it quite right, since I'm working from memory, but what I took away was the idea that it used to be thought that a particular gene was just a pattern for making a particular protein, or at most a set of a very few very similar proteins. But what's new is the realization that a sizeable minority--20-some percent maybe?--of the DNA strand actually functions to regulate the sequence and timing of the (more numerous) protein-making genes, and that's where the real action is.

For example, the difference between a wing and a front leg isn't a whole bunch of different genes, it's just a relatively few, relatively straightforward differences in the way the same genes are activated and regulated during embryonic development. This would seem to make adaptation and evolution a much "easier" process than previously thought.

Am I close at all?

Ordinaryguy you are spot on!
The difference between us and say chimps is not the genes but the timing. The interactions in a cell are all relays of signals carried by proteins in a sort of tag team of on/off signals. Proteins are coded by genes and the expression of genes is controlled by proteins.

The interesting parts of cells and what makes creatures different is the order the genes are transcribed and translated (made) into proteins and then for how long.

Some genes are controlled by the protein they express- the expressed protein can act in a feedback loop suppressing expression when levels are high enough. Other genes can be expressed when a metabolite or substrate for the gene's protein reaches a critical level.

This a very interesting area of science (of course I would say that being a biochemist) I'll be back later and find some cool examples.

In the second pargraph I think you are referring to Hox genes- the genes which control the order of what is express and therefore what grows where

"The key determining factors are (1) concentration ; (2) location ; (3) timing ; and (4) target gene specificity [of the hox gene's products]." Hox genes descovery in fruit flys

Hox genes were descovered in fruit flys (fast breeding, short lived, you can do what yuou like to them= excellent for genetic studies) from examining natural mutant that have legs in the place of antenna - Antennapedia

You can replace fly Hox genes with human Hox genes and still have a normal fly they are that conserved. Obviously you're not allowed to do the experiement the other way round...

If you actually want an easy read on this subject Matt Ridley has written an excellent book called Genome which I would recommend. It is 'pop science' so it is written ina scholarly yet not academic way- it assumes you are smart but you don't have to know any backgroud to understand it. It is also quiet humerous- well if you are geeky like me anyway...
The Great Debate Contributors: Matt Ridley
His book the Red Queen deals with the original posted question.

My own opinion on the original question is evolutionary theory has ben proven time and time again by increased understanding of genetics and developmental biology. You only have to compare foetus of animals to 'see' evolution. I have attatched a pic- I will only give out the link if I have to as the site it is off will probably send this discussion way off!

You can also map evolution in our mitochondrian DNA and trace back common ancestors- it can even be used as a molecular clock to determine when something changed.

Recently we have seen evolution in our very own DNA against the AIDs virus as we are fighting an arms race against it- in areas of high infection rates people are increasing the copies of a protective gene. Interestingly chimps who carry but are mostly immune to AIDs have multiply copies of this gene already- it seems we need to get to their level in order to be protected as well. This evolution is happening in front of our eyes!
These are the receptors I am referring to - they are involved in the immune system Sorry it's a journal

There are tons of examples where evolution has been traced via genes or actively watched. I think this is much more interesting than the old is evolution real question!

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Yes. You are both right, absolutely. Sorry I was slow to get back. One of my kids has finals and needed some organizing and tutoring yesterday...

But absolutely, I agree with both of you. The human genome project revealed that there are far fewer genes than most people expected (and also that a huge fraction of them are regulatory). Lots of consequences to this paucity of genes. One is that we don't have MORE genes/more complexity than "less complex" organisms.

Another consequence is that there isn't necessarily a gene for each protein that we make, or two or three genes if we need more of that same protein. When a protein is express (childhood, adulthood, 7 am or 5 pm), where its expressed (brain cells, skin cells, heart cells), and how much of each protein are virtually all controlled by regulatory genes or molecules.

Also, cells can often make more than one protein from the same gene, by cutting and splicing in different places. (Just as you could take a sentence and use the words in it to make one or more other sentences, by leaving out different words each time.) And a given gene can influence not just one trait but ten or 100. So the "gene for a growth factor" might influence cell division, hair length, longevity, and skin color--AND it might affect all these things differently under different circumstances. So the same gene might cause you to have really long hair if you were exposed to lots of light or eating a certain nutrient or no hair in a different environment.

I'm making up this example, unfortunately. But the idea is right. In fact, there is a case of a researcher creating a mouse that lacked an important gene for a growth factor. That's a gene "knockout." They thought the mice lacking the gene would probably all die. Instead the mice ended up with really long hair, down to their little paws.

Another example of how genes operate: small amounts of a hormone can cause bone cells to accelerate bone growth, while large amounts of the same hormone can cause bone loss (by changing gene expression in bone cells). In other words, hormones and other signaling molecules are rheostatic, and not necessarily linearly either.

Lastly, and this is the area that I think is most cool, the regulation doesn't just take place during early development (in embryos). It goes on throughout the life of the organism. There are species of fish that in one social situation are female, but if the dominant male is eaten or otherwise disappears, one adult female will respond by turning into a male within about 4 days! This is not an isolated example of major changes occurring in response to social or other environmental changes. It's common, although obviously a natural sex change is a cool example.

Even in humans, gene regulation changes according to our behavior and our environment. So, in a sense, you can think of the genes as less like a blueprint (which is a poor analogy) and more like a keyboard, like you are typing at now. And it's the enviromnent that is typing, inputting information to the genes in each cell by way of communication molecules such as hormones, pheromones, paracrine signals, prostaglandins, and neurotransmitters. We think of most of these signalling molecules as operating inside the body, but ultimately they are influenced by things that occur outside the body or in response to the body's two-way interactions with the outside world, what you eat, who you talk to (and what they say to you!), who your relatives are, and how they behave towards you. And so on.

It used to be thought that the bones were like steel girders, strong and immutable, but not only do they heal when they break, but they change shape in response to different uses. So if you take up badminton at age 45, the exercise will reshape your muscles and exert forces on the bones in your arms that subtley reshape and strengthen different parts of your bones. The same thing happens to the brain. It can reshape itself in response to changes in use.

One thing this means is that when researchers find "differences in brain structure" between two group of people, you don't know if it's caused by genetic differences or by differences that developed in the womb in response to differences in exposure to hormones, stress, and nutrition, or by differences that developed during childhood (in response to same), or by differences that developed last year...To say that differences are "biological" means only that you can see the difference. And, thanks to more and more powerful imaging technology for looking at the brain, we can see more and more differences.

I read about some researchers who were using MRI studies of the brain to look for differences in brain structure between "good" mothers and "bad" mothers, so they could (eventually) decide whose kids should be allowed to stay with their mothers and whose should be taken away and put in foster care, based on an MRI. I found this really creepy...especially knowing that brain structure can change in adults. But many medical researchers and psychologists still live in the past, when everyone assumed that "biological" differences meant innate, genetic, and immutable. I think the interface between environment and gene expression is probably THE hottest area of research in biology right now.
End of soapbox.
Good morning! I just have my coffee...
Asking

Me, too! Thanks for all this interesting stuff!

I really should get Ridley's book, haven't read any of his books....

Genetic and protien interactions, signalling and regulation really is 'where it's at' it's a shame it takes quiet a bit of wading through a dry subject to get to it. I'm finding that genetics has become more of a tool for working out systems than the actual 'science' these days. Cloning has become so routine we have a service for it, although when the grant money runs out we have to do it ourselves .

I really like how you mentioned how one gene can control many phenotypes- it is something many people don't realise they think of genes as being very gene X makes me tall, gene why makes me blonde. We are very beautiful systems.

Ridley's great- it was his books that got me into biochemistry.

This is SO COOL. Thank you both for responding in such careful and thoughtful detail. I have a more than passing interest in the subject, since I raise beef cattle breeding stock for a living, and the interaction between husbandry practices and genetic potential is, I believe, a hugely important and widely misunderstood subject.
Likewise for many animal scientists, unfortunately.

I'll give you an example. For at least the last 30 years cattle breeders have been selecting for growth, and closely related factors such as milk production. As a result, cattle have been getting larger and larger and raising bigger and bigger calves. That's fine, except that they forgot that growth and reproduction are fairly antagonistic traits, so now the industry is trapped in this spiral of having to supply more and more expensive feed just to get these big, heavy milking cows to breed on time. A cow that doesn't breed back is a financial failure, no matter how big her last calf was.

Also, the common practice is to raise young breeding stock with access to as much high-energy feed as they can possibly eat, thinking that this is how to tell which individuals have the most "genetic potential" for growth. But all it REALLY tells you is which ones grow fastest under conditions of no nutritional stress at all. Guess what happens to these pampered and overfed young animals when they are kicked out in a range or pasture situation where either the quality or quantity of forage resources is limited, as it certainly will be in some years, and at some times of every year. That's right, too often they fall apart because they never had to develop the ability to adapt to nutritional stress, even though cattle and most other ruminants are admirably equipped and quite capable of doing exactly that.

As I see it, the new realization that the genome and the environment are involved in a lifelong interactive dance is very good news, because it means that fixing our past breeding mistakes will be easier. All we have to do is apply the right kind of selection pressure and husbandry practices to reactivate the latent ability to adapt to real-world, I.e., economically realistic, conditions. Only a tiny minority of breeders has grasped this so far, but I'm absolutely convinced that it's the wave of the future.

Thanks again for the great discussion. Keep it coming.

Aaagh!

Hi Templelane, I didn't actually see the picture you posted the first time. I just saw it and wanted to tell you that this particular image has been debunked. I think it comes from Haeckel. I assume this is either the original from the 19th century, or a redrawing. Anyway, it turns out to be inaccurate--although I don't know in what specific ways. Only that it supposedly exaggerates similarities among embryos.

Creationists have made hay with this 150-year-old error. It IS true that there are correlations among different kinds of vertebrate embryos. For example, all you have to do is look at the photo of the dolphin embryo in wikipedia's article on dolphins to see how much more similar early embryos are to one another than the corresponding adults are. I.e., the dolphin embryo looks like a human embryo. Mouse embryos look like human embryos.

BUT it's also not true that "ontogeny recapitulates phylogeny" exactly. People tend to go all one way or the other with this, when the truth is somewhere in between. But those of faith get pretty worked up over this supposed attempt to deceive people So I wanted to warn you that that image in not quite right. Better to stick with photos of embryos. Mammal embryos are of course even more similar to one another than if you go to birds or (other) reptiles.
Best,
Asking