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Description
Dr. Manton is a cat breeder and she explains the process of artificial selection starting with a Siamese cat crossed with a Persian and ending with several exotic variations after years of careful
...breeding and crossing.
In natural selection a mutation will only make itself felt in the population if it confers on the individual some selective advantage.
The points to be made are that selection is a very real thing and
can be very exactly controlled. That a knowledge of genetics is of
tremendous importance to anyone who breeds animals or plants and that the nature of a species, even humans, could be changed by selection.
| 51 | 00:04:10,000 | 00:04:15,000 | ..and the pale Peppered Moth is quite inconspicuous. |
| 51 | 00:04:13,000 | 00:04:17,000 | One of the reasons why we wanted to breed them was their delightful temperament. |
| 52 | 00:04:16,000 | 00:04:19,000 | The dark form here is rather more obvious. |
| 52 | 00:04:18,000 | 00:04:19,000 | Michael Pentz: Well this one is purring like a bomb. |
| 53 | 00:04:20,000 | 00:04:23,000 | Sidnie Manton: Well he’s been one of the most successful of the British colour points. |
| 53 | 00:04:21,000 | 00:04:27,000 | In industrial districts the tree trunks are black, black with soot, and here… |
| 54 | 00:04:25,000 | 00:04:29,000 | He’s won a great deal on the show bench and in the winter he has… |
| 54 | 00:04:28,000 | 00:04:35,000 | ..the pale form is very conspicuous whereas the dark form is almost impossible to see. |
| 55 | 00:04:30,000 | 00:04:33,000 | ..an enormous frill round there. He’s a very amiable boy and if… |
| 56 | 00:04:34,000 | 00:04:37,000 | ..he can persuade anybody to scratch his tum well that is just ideal. |
| 55 | 00:04:37,000 | 00:04:43,000 | Doctor Kettlewell and Professor Tinbergen took a film of these moths in the wild… |
| 57 | 00:04:38,000 | 00:04:41,000 | (Michael Pentz) Having got, perfected rather, this basic colour point… |
| 58 | 00:04:42,000 | 00:04:46,000 | ..have you attempted to develop any new cats from there? |
| 56 | 00:04:44,000 | 00:04:49,000 | ..and you can see in this how we can explain the difference in the distribution. |
| 59 | 00:04:47,000 | 00:04:50,000 | Sidnie Manton: Yes, we’ve attempted to get two new colour patterns. |
| 57 | 00:04:50,000 | 00:04:53,000 | (Peggy Varley) In Doctor Kettlewell’s first series of experiments he… |
| 60 | 00:04:51,000 | 00:04:55,000 | Now, the original were seal points and blue points that I’ve just shown you. |
| 58 | 00:04:54,000 | 00:04:57,000 | ..marked live moths with paint then released them and… |
| 61 | 00:04:56,000 | 00:04:59,000 | We then imported the brown gene from the short hairs from… |
| 59 | 00:04:58,000 | 00:05:00,000 | ..counted the numbers recovered at a light trap. |
| 62 | 00:05:00,000 | 00:05:03,000 | ..chocolate point Siamese and from Havana and we’ve got here a… |
| 60 | 00:05:02,000 | 00:05:05,000 | In the second set of experiments he fixed moths to… |
| 63 | 00:05:04,000 | 00:05:08,000 | ..chocolate point colour point, not such good type as the older ones… |
| 61 | 00:05:05,000 | 00:05:08,000 | ..the bark of trees and observed what happened to them. |
| 64 | 00:05:09,000 | 00:05:11,000 | ..because the breeding of this has only gone on for about… |
| 62 | 00:05:09,000 | 00:05:13,000 | Here in a Dorset wood it’s easy to see the dark moth against… |
| 65 | 00:05:12,000 | 00:05:14,000 | ..12 years and that’s as far as I’ve got. He looks much better in… |
| 63 | 00:05:14,000 | 00:05:17,000 | ..the lichen covered tree but difficult to see the pale form. |
| 66 | 00:05:15,000 | 00:05:19,000 | ..the winter when he’s got a good frill but there he is, he’s got very nice blue eyes. |
| 67 | 00:05:20,000 | 00:05:24,000 | Now put the blue dilution factor into the genetics of the last one and you get… |
| 64 | 00:05:20,000 | 00:05:24,000 | The birds go for the moths they can see, in this case the melanic form. |
| 68 | 00:05:25,000 | 00:05:31,000 | ..the lilac point there with a lovely pale body colour which stays throughout life. |
| 65 | 00:05:29,000 | 00:05:33,000 | The lighter moths, on the other hand, remain beautifully camouflaged. |
| 69 | 00:05:32,000 | 00:05:35,000 | If you don’t have the Siamese colour pattern you have the self-lilac… |
| 70 | 00:05:36,000 | 00:05:39,000 | ..which is a new thing, and you have the self-chocolate too. |
| 66 | 00:05:37,000 | 00:05:39,000 | Then Doctor Kettlewell repeated the experiment in… |
| 71 | 00:05:40,000 | 00:05:45,000 | So there were our four new kinds of cat and… |
| 67 | 00:05:40,000 | 00:05:42,000 | ..an industrial area and of course the opposite happened. |
| 68 | 00:05:43,000 | 00:05:46,000 | The pale typical form is easily spotted by the birds and… |
| 72 | 00:05:46,000 | 00:05:49,000 | ..it’s taken me about 12 years to make them and you see - |
| 69 | 00:05:47,000 | 00:05:50,000 | ..gobbled up whereas the black mutant is overlooked. |
| 73 | 00:05:50,000 | 00:05:51,000 | Michael Pentz: I like the way you say make them Dr Manton, it seems… |
| 74 | 00:05:52,000 | 00:05:54,000 | ..there’s a great deal of deliberation in what you do, not very much hit or miss. |
| 75 | 00:05:55,000 | 00:05:56,000 | Sidnie Manton: No, no, we know just how to do it… |
| 70 | 00:05:55,000 | 00:05:59,000 | These melanic moths have completely escaped detection by the birds. |
| 76 | 00:05:57,000 | 00:05:58,000 | Michael Pentz: There’s evidently a bit of genetic engineering practically? |
| 77 | 00:05:59,000 | 00:06:04,000 | Sidnie Manton: You’re doing the two things. You’re selecting and planning your genetics. |
| 71 | 00:06:01,000 | 00:06:06,000 | So birds hunting for insects by sight act as the agents of Natural Selection. |
| 78 | 00:06:05,000 | 00:06:08,000 | (Michael Pentz) And would you say that knowing as much as you do… |
| 72 | 00:06:07,000 | 00:06:11,000 | They pick out the conspicuous forms and leave the ones… |
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