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Post by keen101 (Biolumo / Andrew B.) on Jan 4, 2013 13:31:38 GMT -5
Thank you for this. Lamarck never gets enough credit, and Darwin always gets too much. Darwin had a few things going for him that Lamarck probably didn't. Darwin had the time period and the culture, the English language, and most importantly he could write well.
Glad to see new evidence supporting Lamarck coming forth.
p.s. if anyone knows where i can read Lamarcks own writings please let me know (no matter what language they are published in). I would be very interested in reading anything that comes from Lamarck directly.
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revi
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Post by revi on Jan 5, 2013 7:16:37 GMT -5
Actually, it's not Darwin but rather Weissman theory, which take the veil of "Neo-Darwinism" and has been injected to us by "official scientific community". Darwin himself isn't against the notion that external environment can alter organisms and that alteration can be brought forward to next progeny.
Lamarck's original writings are now very rare, but searching google with "evidence of Lamarck theory" can get many informative sites.
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Post by revi on Jan 5, 2013 7:34:23 GMT -5
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karl
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Post by karl on May 25, 2014 9:09:18 GMT -5
Lysenko was demonized by the neo-Mendelists (mostly Eugenicists) after he condemned Eugenics as the "fascist distortion of genetics and the fascist utilization of genetics in its political aims". Lysenko was accused of politicizing genetics by the same Eugenicists who persuaded governments that forced sterilization was a benefit to "society".
Lysenko did not deny Mendelian phenomena, but did understand that there is far more to heredity than the neo-Mendelists could comprehend. And he observed in countless crosses that agriculturally important characteristics (e.g., time of flowering) did not always behave as Mendelian unit characters.
For example, Lysenko had discovered that for some strains of winter wheat, flowering was dependent on photoperiod. Other strains were influenced by heat (higher temperatures hastened flowering, lower temps delayed flowering). And when a photoperiod-dependent strain was crossed with a heat-dependent type, the offspring were dependent on neither heat nor light (within the conditions normally encountered by crop plants). In one public demonstration, two strains were selected, both flowering too late in the vicinity of Odessa, Ukraine to ripen their seeds reliably. The cross-bred seedlings (grown in the field near Odessa) flowered earlier than either parent, and ripened their seeds early enough to escape frost damage.
In subsequent generations, early-ripening plants were selected until a new strain was produced that could be cultivated near Odessa. There is nothing strange about this, I think. And yet, Joravsky (The Lysenko Affair, 1986) amused himself by mocking the absurdity of a technique that had already been verified in practice.
"Lysenko himself, for all his daring, responded only in 1933, when the fortunes of vernalization as a sowing technique seemed to sag, and then he acted quietly. Not until 1934 did he begin to reveal his newest and boldest project in his usual sensationalist way. Without benefit of growth chambers or any special appropriation, “in five flowerpots in a corner of a crowded greenhouse,” he began to breed an improved variety of spring wheat for the Odessa district. He promised to have the new variety ready for production testing in 1935. The total breeding time would not be four or five years, as the inspectors had decreed, but less than three. Of course, it was vernalization that made this miracle possible.
As usual, Lysenko’s procedure was quite simple. He picked a spring wheat with a short “stage of vernalization” but a long “light stage,” and crossed it with a variety that had a long “stage of vernalization” but a short “light stage.” Exactly what he meant by these stages was not made clear, a difficulty that plant physiologists were learning to endure, out of deference to “public opinion.” Now Lysenko brought the difficulty to plant breeders and geneticists. By virtue of his stage theory he knew in advance that his cross would produce offspring that would ripen sooner and therefore be higher yielding than either of its parents. He did not have to test a multitude of plants through many generations. He selected the earliest plants in the first hybrid generation, knowing in advance that their earliness and therefore their higher yield would be transmitted to their offspring. The italicized phrases dismayed wheat specialists and geneticists, for they revealed utter ignorance, or disregard, of firmly established elementary principles."
I find it amusing that Joravsky could write of a greenhouse, and in the same paragraph deny that any sort of "growth chamber" was involved. He also failed to mention that the other parent-strain in the cross was grown in the ground, under a moveable shed that allowed the photoperiod to be controlled. The greenhouse, by the way, provided the extra heat needed to hasten the flowering of the heat-dependent strain. Thus, both strains were hastened into bloom (or earing) so they could be crossed. And the "specialists and geneticists" Joravsky mentioned would have been further dismayed if they had paid attention long enough to learn that the demonstration worked ... just as it had in the past. The same technique was also used to produce earlier flowering sesame plants.
Joravsky's book is endlessly entertaining to those of us who have read Lysenko's works. Here's another example:
"Far more daringly he announced that potato tubers can be vernalized, though they are not true seed, if they are sprouted in warmth and light. Thus he renamed and advertised as his discovery what was actually an ancient technique of potato growers -- sprouting the tubers before planting in order to give the crop a head start. In this case "vernalization" usually does increase yield, if it is done the ordinary way instead of Lysenko's. He urged farmers to string up the seed tubers on wire or cord, which would have increased labor costs and the dangers of infections."
Here we see just how shamelessly Joravsky distorted the facts. Chouard (1960) wrote, "As an example, chilling potatoes to increase tuber yield, though commonly but wrongly named 'vernalization,' merely utilizes an aftereffect of cold on vegetative vigour and has nothing to do with the specific aim of vernalization which is to induce the capacity for flowering." Joravsky got the temperature wrong. But Chouard was also partly wrong. Chilling potatoes induces the tubers to convert starch to sugar, which hastens the growth of the shoots since they don't have to wait for the starch to be converted.
Furthermore, Lysenko's advice was to cooks, not to farmers. On a visit to a cooperative farm, Lysenko was told by the farmers that they didn't have enough potato "seed" to plant. He promptly asked the cooks to cut off the rosette end of the largest tubers, and hang them on a thread or wire in a cool, dry place. These were to be taken to the potato farmers for planting.
This was good advice for two reasons. First, he encouraged people to find local solutions to local problems. Second, as Arthur (1892) had already demonstrated, terminal "eyes" give higher yields than side "eyes", and "seed" taken from large tubers gave higher yield than "seed" of the same size taken from smaller tubers.
bulbnrose.x10.mx/Heredity/Arthur/ArthurPotato1892.html
Michurin, by the way, did deny that Mendelian phenomena occur -- but only in his early work of crossing locally adapted varieties with imported forms. Later, when he began to seek hardiness and resistance from foreign varieties (e.g., from Manchuria, Korea, etc.) and crossing these with the cultivated foreign plants (i.e., crossing plants that were equally foreign), he found that the results came closer to what Mendel saw in his varietal crosses.
That is to say, parents that were long adapted to local conditions had a stronger influence on their hybrid progeny than foreign varieties. When both parents were foreign, but native to different places, there was no such overwhelming prepotence.
Finally, on the subject of Soviet plant breeders (they weren't all Russian), I'd like to mention N. V. Tsitsin. He was also a Michurinist, but was primarily interested in "Wide Hybrids". This term includes parents that are geographically as well as taxonomically remote. His book 'Wide Hybridization in Plants' was what got me interested in what those guys in the Soviet Union were really doing.
So, for anyone interested in starting with wide hybridization, it may be easiest to collect specimens or strains of a single species from widely different regions or climates.
Darlington, Evolution of Genetic Systems (1958)
"Two geographically separated varieties of Hordeum sativum give a vast array of segregation in their progeny which is not seen when parents with similar differences of form come from the same region."
This could be a useful way to "crack" species so they can be used for crossing with cultivated types. For example, Rosa suffulta/arkansana is found from Texas into Canada. Crossing geographically remote forms of the species should produce "wide hybrids" that would be more obliging in crosses with cultivated roses.
Karl
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karl
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Post by karl on May 25, 2014 9:44:53 GMT -5
As Kidd & West (1918) explained:
"IT may not always be fully realised to what a degree the developmental capacity of plants is pre-determined by the action of environmental conditions during the earliest stages of their life-histories. During the course of germination and in the seedling stage, or even earlier during the sojourn of the seed upon the parent and in the dormant period, the "potentialities" of plants may be affected by actions which only subsequently produce visible results. These results appear during the later stages of development, without reference to the conditions then existing. In this way adverse conditions in the later stages of development may not suppress a vigour of growth which has been pre-determined under favourable conditions during the ripening of the seed in the previous year; or favourable conditions during summer may fail to increase the yield owing to adverse conditions which have previously operated during the period of germination. It is such effects, namely those which are to be traced to the environmental conditions which have operated in the past stage of the plant's life, that we may term effects of physiological pre-determination in order to mark their distinction from those which are due to hereditary causes."
bulbnrose.x10.mx/Heredity/King/PositionEffects.html
I originally called this bibliography "Position Effects", referring to the differences in plants raised from seeds collected from different parts of the plant or fruit, but changed it to "Physiological Predetermination" when I happened on the works of Kidd and West.
This topic also includes the differences in plants raised from immature, old, or fresh but small/deformed.
Old seed was long-ago considered especially valuable for growing cucumbers and melons. The plants are less vigorous, have fewer branches, but produce a greater proportion of female flowers. They are also earlier flowering. These are particularly useful for gardeners who have limited space, and/or a short growing season.
Balsams (Impatiens balsamina) were also said to be earlier, more floriferous, and more double when grown from old seeds. A professional cabbage grower recommended old seed for growing cabbages. The plants produced fewer guard leaves and larger heads.
The principle of Physiological Predetermination also applies (in some cases) to pollen taken from different anthers of the same flowers.
Donald Beaton (The old Scotch gardener from Inverness) wrote in 1861 of his important discovery:
"In the great bulk of the Scarlet or Horseshoe Geraniums there are but seven stamens, four long ones, one of medium length, but which is often wanting, and two almost sessile like the anthers of Wheat—that is, very short indeed, and opening at the bottom face to face. These two are they which reduce a whole family to beggary; first to dwarfs or Tom Thumbs, or better still, to minimums, or the smallest of that kind consistent with vigour sufficient to become a useful plant in cultivation, and, lastly, to the brink of ruin, and drive that race out of existence altogether, if there were not other means provided to arrest the decline, or keep it from manifesting itself at all in a state of Nature."
The pollen from these short stamens usually is not carried from flower to flower. And if it is mixed with the "stronger" pollen of the long stamens, the latter pollen takes the lead. So, to grow dwarf geraniums (Pelargonium), the pollen from the short stamens must be used alone.
And shortly after Beaton's publication, Isaac Anderson-Henry (1861) wrote of his own work with pollen from the short stamens of Rhododendrons, Azaleas and their kin. He also raised dwarf plants, but the most valuable results came from using pollen from the short stamens of large species to fertilize the flowers of smaller species. In this way he raised hybrids of species that others had failed to cross.
Bradley (1906) also used pollen from long and short stamens of Amaryllises (Hippeastrum), and like the others found differences in the progeny.
"Seeing that the top division of the perianth is always the largest and best coloured, I generally use the anther, the filament of which is adnate to this division; whether this be the reason or not I do not know, but the progeny generally have more equal divisions to the perianth, and the bottom division is greatly improved.
On the other hand, with a view to getting as white a bloom as possible, I use the bottom division (generally all white) from the white red-striped varieties; and in the seedlings the flowers have much less colour; but the shape of the bloom is spoilt, the divisions being narrow."
I currently have a pot of Amaryllis seedlings that resulted from the use of pollen from the shortest stamen. It will be a couple of years before they bloom, at least, so I'll have to wait to see whether they have petals that are narrower than those of the parent.
Karl
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Post by revi on Jun 20, 2014 10:59:39 GMT -5
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Post by cletus on Jul 29, 2014 13:47:44 GMT -5
More evidence for graft hybrids, specifically graft induced asexual allopolyploidy. Not quite a Michurinian method, but it is still unknown how his methods may have intersected with this phenomenon. I wonder how such an experiment might be influenced by the combinations of differentials Michurin explored with grafting (age, time, biomass, genetic). www.mpg.de/8266137/new-species-asexual-path"Making new species without sex Plants can transfer their entire genetic material to a partner in an asexual manner June 10, 2014 Occasionally, two different plant species interbreed with each other in nature. This usually causes problems since the genetic information of both parents does not match. But sometimes nature uses a trick. Instead of passing on only half of each parent’s genetic material, both plants transmit the complete information to the next generation. This means that the chromosome sets are totted up. The chromosomes are then able to find their suitable partner during meiosis, a type of cell division that produces an organism's reproductive cells. This allows the plants to stay fertile and a new species is generated. Examples for such a combination of two genomes, called allopolyploidy, are found abundantly in both wild plants and crops like wheat, rapeseed and cotton. Now, for the first time, Ralph Bock’s group at the Max Planck Institute of Molecular Plant Physiology could show that new species can be generated in an asexual manner as well. Natural grafting between an oak (left) and a beech (right). The complete genetic material can be exchanged between the graft partners at contact zones such as these. This can result in the generation of new plant species. Zoom Image Natural grafting between an oak (left) and a beech (right). The complete genetic material can be exchanged between the... [more] © MPI f. Molecular Plant Physiology As in previous studies, Bock’s group at the Max Planck Institute of Molecular Plant Physiology used a method called grafting. It is generally known from nature that plants are able to grow together at their contact zones. In horticulture and viticulture, growers make use of this ability to bring characteristic traits of two varieties together without crossing them. For example, this method is used to play a trick on grape phylloxera, a notorious pest of commercial grapevines that attacks the roots of the plants. By grafting pest-sensitive elite grape cultivars onto pest-resistant wild rootstocks infestation is effectively prevented. It was generally believed that a combination of desired traits can be obtained by grafting, but there is no exchange or recombination of genetic material – so-called horizontal gene transfer - between the grafted plants. “In our previous work we were able to prove that, contrary to the generally accepted dogma, there is horizontal gene transfer of chloroplast genes at the contact zone between grafted plants. Now we wanted to investigate if there is a transfer of genetic information between the nuclei as well” Ralph Bock says while explaining the recent study. The researchers introduced resistance genes against two different antibiotics into nuclear genomes of the tobacco species Nicotiana tabacum and Nicotiana glauca, which usually cannot be crossed. Afterwards, Nicotiana glauca was grafted onto Nicotiana tabacum or the other way round. After fusion had occurred, the scientists excised tissue at the contact zone and cultivated it on a growth medium containing both antibiotics, so that only cells containing both resistance genes and thus, DNA from both species, should survive. Surprisingly, the scientists succeeded in growing up numerous doubly resistant plantlets. To determine if the acquired double resistance is due to the transfer of single genes or the transfer of the entire genetic material, the researchers counted the chromosomes in the nuclei of the resistant plants. If complete genomes were transferred, the new plants would contain the sum of the chromosome numbers of the two species. “Indeed, we found 72 chromosomes in the resistant plants”, Ralph Bock explains, “72 is the sum of the 24 N. glauca chromosomes and the 48 N. tabacum chromosomes.” Thus, plantlets generated from the graft junction contained the genetic information of both species. “We managed to produce allopolyploid plants without sexual reproduction”, Sandra Stegemann, joint first author of the study, is pleased to say. When the scientists grew their new plants in the greenhouse, it became obvious that they combined characteristics of both progenitor species. But there was one striking difference: the new plants grew remarkably faster than their parents. Such a fitness advantage is also known from allopolyploid plants in nature and from the superior growth properties of allopolyploid crops. Since the newly generated plants were able to reproduce sexually and their progeny was fertile as well, one can consider them as a new species. The scientists named it Nicotiana tabauca. “Thus, grafting two species and selecting for horizontal genome transfer could become an interesting method for breeders who could use this approach to create new crop plants with higher yields and improved properties”, is the unanimous opinion of the scientists involved in the present study. " |
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Post by revi on Jul 19, 2018 11:58:27 GMT -5
Another example (https://www.nature.com/articles/nn.3594) how acquired characters can be inherited.
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Post by keen101 (Biolumo / Andrew B.) on Jul 19, 2018 12:13:03 GMT -5
Another example (https://www.nature.com/articles/nn.3594) how acquired characters can be inherited. Thanks revi, that's pretty cool. The same thing happened with starving people of the holocaust and their children having problems with being fat. But I don't see how that has anything to do with Michurin and cross-species hybrids or grafting. Lamarkian genetics sure (epigenetics), but I don't see the link with Michurin...? |
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Post by revi on Jul 21, 2018 7:19:39 GMT -5
Actually, Michurin gives much more emphasis on the environment in which the plant has been nurtured. To him, this nurturing is much more important. The varieties that he has made is based on this theory. As per his theory, the zygote has the trends of both the mother and father and the trends towards which the zygote will grow will depend on what kind of environment it has been kept. It the environment is the same/closer to the environment as the father, the offspring will have the trend to become more father like and vice versa.
I have posted a few links about works of Michurin in this thread. Kindly read those materials.
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Post by keen101 (Biolumo / Andrew B.) on Jul 21, 2018 8:11:17 GMT -5
Actually, Michurin gives much more emphasis on the environment in which the plant has been nurtured. To him, this nurturing is much more important. The varieties that he has made is based on this theory. As per his theory, the zygote has the trends of both the mother and father and the trends towards which the zygote will grow will depend on what kind of environment it has been kept. It the environment is the same/closer to the environment as the father, the offspring will have the trend to become more father like and vice versa. I have posted a few links about works of Michurin in this thread. Kindly read those materials. Cool. Makes sense. |
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Post by revi on May 23, 2019 9:41:24 GMT -5
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