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Only on paper, I take it?
Let's say the mother and father are both Bb. The offspring will "be" BB, as you say. What happened to the b from each? They are not present in that genetic makeup of that offsping?Let me phrase it another way.
Let's say I have a gene for x-ray vision (we'll call it the X-gene), and let's say that my husband doesn't. When I fell pregnant with my daughter, she would have a 50% chance of getting the X-gene. We can't be sure until we either do a genetic test or we just wait and see if she can see through walls.
The dominant and recessive stuff is closely related to this topic. Eye colour is a good example. Genes can come in different versions, called "alleles." You have genes for eye colour, and two of the alleles are a brown eye allele, and a blue eye allele.
I have blue eyes, and my mother did too. My father has brown eyes. Brown eyes are a dominant trait. Each person has two copies of the gene for eye colour, one from their mother and one from their father. In the diagram below, a gene for brown eyes is denoted with a "B", while the gene for blue eyes is a "b".
With a dominant gene, if you have one copy, you will have the trait. With eye colour, brown eyes are the dominant trait. So, if your eye colour gene combination is Bb, then the B (being dominant), will override the b, and the person will have brown eyes.
In the first chart, both parents have one of each, so they both have blue eyes. Let's say the mother is along the top, and the father is down the side. You can see that both the mother and the father have Bb genes, so they each have brown eyes. They each have a copy of the blue eye allele, but since they also each have the dominant brown eye allele, that overrides the blue, and they each have brown eyes.
When they procreate, half of their genes each go to their offspring (the different ways the genes can combine are represented by the squares in the middle. In the top left square, we see what would happen if the mother (on the top) provides her B allele and the father provides his B allele. The offspring will have the gene combination BB, which is two genes for brown eyes. So their child in this case will have brown eyes.
But when we look at the top right square in the first example, we see that the mother provides a b allele, the recessive blue eye gene. But the father still provides his dominant B allele. With a gene combination of Bb, the offspring has a dominant brown eye gene which overrides the blue eyed allele, and so the offspring will again have brown eyes. However, in this case they still carry an allele for blue eyes which might get passed along when they have children.
Pretty much the same thing happens in the lower left square, although this time the father is providing the b gene and the mother is providing the B gene.
In the lower left square, both parents provide the recessive b allele, and since this offspring only gets the b alleles, they will have blue eyes.
The second example is what happened with my parents (which is why I proposed that the mother is represented by the top). My mother had blue eyes, so she could not have had a B allele (since if she did, it would have given her brown eyes, since it is the dominant version). So she must have had the bb combination. I can also figure out that my father had a Bb combination. After all, if his combination was BB, then I MUST have received a B allele from him, and since that is the dominant allele, I would have had brown eyes. So I must have got a b allele from him, plus one of my mother's two b alleles, thus giving me bb as well.
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So for the TOE to demonstrate that the heffalump is related to the mastodon, don't they need to show the many steps between?The definition of "species" is a rather difficult one. It's typically defined as a group of individuals who can produce fertile offspring. So all the different kinds of dogs are considered the same species, since you can breed a Dalmatian and a German Shephard and the puppies will be fertile themselves. But the example you used a while back with horses and donkeys producing mules, well, since mules themselves are sterile, then horses and donkeys are considered different species.
But it all depends on how closely related two groups are. Let's say you have a population, and they are divided for some reason. Let's say that a river changes course during a flood, and now you have two groups, one on each side of the river, and they can't interbreed any more. Each population will now evolve in their own way, and since conditions on the different sides may be different, the two different populations will evolve to suit the unique pressures they face, and thus they will gradually become more and more different.
If you come back ten years after the separation and take a female from the north side and a male from the south side, they'd probably still be able to interbreed. That wouldn't be enough time for them to evolve apart enough to make them different species. But if you come back a thousand years later, you could find that there's more trouble getting them to breed successfully. And if you came back a million years after, you'd probably find they wouldn't be able to interbreed at all.
But there's no one point where it stops being Species A and becomes Species B. Even if we look at a single population and consider individuals who are isolated not by space, but by time, we'd see the same thing. You could follow a group of animals and watch as they evolve over a million generations. G1 would be able to breed with G2 (and several generations down the line too). G15 would be able to interbreed with both G14 and G16. G165,287 would be able to interbreed with G165,286 and G165,288. But you would likely find that G165,287 could NOT breed with G1. Even though each generation changes only slightly, those slight changes all add up. Over a small number of generations, those changes are not enough to prevent successful breeding, but over many generations, those changes can be enough to prevent it.
So, to get back to your question, the tuskless variant wouldn't be considered a separate species, For that to happen, the tuskless elephants would need to be different enough from the tusked elephants that interbreeding could not produce fertile offspring.
Exactly.Let's say the mother and father are both Bb. The offspring will "be" BB, as you say. What happened to the b from each? They are not present in that genetic makeup of that offsping?
So for the TOE to demonstrate that the heffalump is related to the mastodon, don't they need to show the many steps between?
Let's say the mother and father are both Bb. The offspring will "be" BB, as you say. What happened to the b from each? They are not present in that genetic makeup of that offsping?
They don't need to show every single step between the two. There are ways of examining the genetic code of two animals and determining how closely they are related, but that gets very complicated, and I'm not that familiar with it.So for the TOE to demonstrate that the heffalump is related to the mastodon, don't they need to show the many steps between?
Ok, let's say both parents are Bb. I guess my question is not quite whether the offspring will 'have', as in demonstrate, the dominant brown eyes or recessive blue eyes, but whether, supposing it to 'be' or 'have' BB brown eyes, does it then have any b it inherited to contribute to the possibility of blue eyes to future generations.Not quite.
If both parents are Bb, then there are different possible outcomes.
If the offspring gets B from the mother and B from the father, then the offspring will be BB and will have brown eyes because it has two copies of the dominant B allele.
If the offspring gets B from the mother and b from the father, then the offspring will be Bb and will have brown eyes because it has a dominant B allele which overrides the recessive b allele.
If the offspring gets b from the mother and B from the father, then the offspring will be bB and will have brown eyes because it has a dominant B allele which overrides the recessive b allele.
If the offspring gets b from the mother and b from the father, then the offspring will be bb and will have blue eyes because it has only the recessive b allele.
So, out of the four options, there's one chance in four it will have BB, two chances in four that it will have one of each (either Bb or bB), and only one chance in four it will have bb and be blue eyed.
I don't know if it really means anything, but:They don't need to show every single step between the two. There are ways of examining the genetic code of two animals and determining how closely they are related, but that gets very complicated, and I'm not that familiar with it.
That's an odd article and I'm curious by what metric they are comparing genes because those number look seriously suspect.I don't know if it really means anything, but:
Chimpanzee: 96 percent identical. By studying the genomes of chimps (which after bonobos are our closest living ancestors), researchers are hoping to understand what makes us uniquely human.
Banana: more than 60 percent identical. ...
If the fact that chimps are 96 percent identical means anything, I would have expected bananas to a lot less identical than 60 percent.
Vegapharm » How genetically related are we to bananas?
Ok, let's say both parents are Bb. I guess my question is not quite whether the offspring will 'have', as in demonstrate, the dominant brown eyes or recessive blue eyes, but whether, supposing it to 'be' or 'have' BB brown eyes, does it then have any b it inherited to contribute to the possibility of blue eyes to future generations.
I hear about some species that have been used as demonstration of current evolution, but the creationists say that, no it is only an ability that species has to adapt to its environment, that is just as easily changed back to its 'original' form, when the environment changed back to its 'original' configuration, and we have seen it happen within our lifetimes.
Not saying this is relevant, but my thinking is along these lines. Out of 5 boys in my family, one doesn't really look much like the other four, but he's almost the spitting image of my grandfather on my dad's side at his age. Another of us doesn't have my dad's personality, but he does have my grandfather's personality.
I don't know if it really means anything, but:
Chimpanzee: 96 percent identical. By studying the genomes of chimps (which after bonobos are our closest living ancestors), researchers are hoping to understand what makes us uniquely human.
Banana: more than 60 percent identical. ...
If the fact that chimps are 96 percent identical means anything, I would have expected bananas to a lot less identical than 60 percent.
Vegapharm » How genetically related are we to bananas?
Let's say the mother and father are both Bb. The offspring will "be" BB, as you say. What happened to the b from each? They are not present in that genetic makeup of that offsping?
So for the TOE to demonstrate that the heffalump is related to the mastodon, don't they need to show the many steps between?
And I realise now that the last two posts of mine were responding to posts that I had already responded to. Ah well.
Only the reservations I already mentioned.@Mark Quayle let's move on. In statement 3, I spoke of how parents pass their genes on to their offspring. We've already covered this a fair bit, what with the different allele's for eye colour and such, so may I assume you have no reservations about that?
Anticipating that you will have no reservations, let's also cover Statement 4, where I said that different traits can influence how well the individual animal that has them survives. Do you have any reservations regarding that statement?
Only the reservations I already mentioned.
I can't accept 'is random'. 'Appears random', perhaps. But I guess I get your point.I think you misunderstood.
If the mother and father are Bb, then there are several different ways that the genes can be passed to the offspring.
- The mother could pass on her B, and the father could pass on his B. In this case, the offspring will be BB and will have brown eyes.
- The mother could pass on her B, and the father could pass on his b. In this case, the offspring will be Bb and will have brown eyes (since the dominant B allele from the mother overrides the recessive b allele from the father).
- The mother could pass on her b, and the father could pass on his B. In this case, the offspring will be bB and will have brown eyes (since the dominant B allele from the father overrides the recessive b allele from the mother).
- The mother could pass on her b, and the father could pass on his b. In this case, the offspring will be bb and will have blue eyes.
Which of these four different results will occur is random, since the allele that the mother passes on is random, as is the allele the father passes on. Each parent has two alleles for themselves (for example, I know I am either bb, or I am Bb with a gene that "cancels out" my B, since I have blue eyes). But I only passed one of them to my daughter.
Both of your examples assume a common ancestor.No. We could each do a DNA test and find out how closely related we are. Chances are we are not closely related at all. But, if we were to go back far enough, we would be able to find a person who is in my family tree and your family tree as well. This person probably lived several hundred years ago, of course. But we could determine approximately how many generations ago we shared this common ancestor. We would not need to trace every single descendant of that common ancestor on both sides in order for us to know approximately when they existed.
When it comes to different species, we can also look at shared traits. For example, let's say feathers (I'm just coming up with an example off the top of my head here). We might look at a hummingbird and an eagle and say that they are two species that are not closely related (in other words, saying their common ancestor lived a long time ago). But we can be quite sure that whenever this common ancestor lived, it was after the line had evolved feathers. I mean, let's assume that the common ancestor lived BEFORE feathers evolved. Then we'd have to assume that the eagle line evolved feathers after the line diverged, and the hummingbird line evolved the exact same trait completely independently in the same time. When you look at the similarities between feathers of hummingbirds and eagles, the chances of feathers evolving twice and being what we find in nature are absolutely miniscule. it's far more reasonable to say that the ancestor evolved feathers BEFORE the two different lines diverged.
Let's look at another example, this time, at a trait that did evolve after divergence. Cows and horses. They both have hooves, and yet there are clear structural differences between them. Each walks on essentially their finger tips, with a hard protective covering on each of the digits that bears the weight. However, in horses, the weight is born on a single digit, and in cows the weight is born on two digits. So it's unlikely that the common ancestor of cows and horses was hoofed. After all, let's say it was. Did it have one hoof or two? If it had two, then all horses (including animals like zebras, etc) must have evolved to lose one. And if it had one hoof, then all cows and related animals (including ox, bison, etc) must have evolved to gain one. So the more rational answer is that the common ancestor had not yet evolved hooves, and both the horse family and the cow family both evolved hooves, but because they could not interbreed and share the DNA which would allow them to pass on traits, they each had to evolve their own version of hooves. And that's why they have different types of hooves.
You may find this website interesting. It shows the tree of life, and you can follow it to see where two different species have a common ancestor. OneZoom Tree of Life Explorer
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