The effective number of clones (Nc) wasestimated for 255 conifer clonal seed orchards in Finland,... more The effective number of clones (Nc) wasestimated for 255 conifer clonal seed orchards in Finland, Korea, andSweden, based on the variation in the number of ramets among clones. Themean census number of clones (N) varied from 70, in 13 KoreanPinus koraiensis seed orchards, to 139 in 176 Finnish Pinussylvestris seed orchards. The mean effective number of clones(Nc) was 66, with
ABSTRACT Genetic relationship within a population can be measured by average coancestry. This ca... more ABSTRACT Genetic relationship within a population can be measured by average coancestry. This can also be expressed as an effective number which represents the relative genetic diversity of the population. The goal of breeding can be formulated to maximise genetic value minus average coancestry times a constant (the “penalty constant”). An iterative search algorithm can then be used to find the best selections for meeting this goal. Two such algorithms, one for a fixed number of selections and the other for a variable optimum number, were applied to select a mixture of field-tested Norway spruce clones with known parents. The results were compared with those from the conventional method of restricting parental contributions to the selected population as a means to control diversity. Coancestry-adjusted selection always yielded more gain than restricted selection at a given effective population size (except under circumstances where the methods were equivalent). Expressed another way, at any given level of gain, coancestry-adjusted selection maintained a larger effective population size than did restricted selection. The relative superiority of coancestry-adjusted selection declined when the effective population size approached the lowest value, that at which no penalty or restriction was applied. The method was extended by the second search algorithm to optimise the selected number of clones. The optimal number of clones can be rather large when diversity is heavily valued, but the reduction in genetic gain becomes large.
The value of a mixture of genetic entries present in different proportions is defined. A measure ... more The value of a mixture of genetic entries present in different proportions is defined. A measure of the disadvantage of reduced diversity is defined as the sum of the squares of the proportions of the different entries. An algorithm for maximizing genetic gain of the mixture under the constraint of a constant disadvantage is developed. The optimal deployment strategy is one that lets the proportion of the genetic entries be linearly dependent on their genetic value. By use of rankits as entries for genetic values, optimal solutions for deployment were calculated for a range of values of available entries (from 10 to 5,000) and preset diversity-related disadvantage-factors (the preset values correspond to mixtures of between 2 and 100 entries in identical proportions). The values are tabulated so they can be used by breeders. The superiority of the proposed strategy increases with the proportion of the available entries which are selected. In the situation that around half would have been selected if truncation selection was applied, the improvement in genetic gain compared to classical truncation selection is up to 18%. Thus, considerable improvements in gain are possible without any sacrifice in diversity. Applications are discussed with particular reference to clonal forestry.
ABSTRACT A theory on the balance between gene diversity and level of nut collection was developed... more ABSTRACT A theory on the balance between gene diversity and level of nut collection was developed and applied to Danish hazelnut (Corylus avellana L.) populations. By controlling female fertility based on the power function F(x)=xa, a trade-off between equalizing maternal contribution and obtaining an acceptable amount of nuts was achieved, and gene diversity during the initial phase of mobilizing the natural gene pool could be managed. Constraints on nut production could be made on maternal proportion as both lower and upper bounds. For a case involving the collection of hazelnuts from 264 individuals, the status number (Ns) was estimated to be 149 based on female contribution if all nuts were collected and used. Higher status numbers could be obtained by balancing the number of nuts collected per tree, but such an increase in the status number would result in a substantial loss of nut production. It was decided to truncate the progeny size at 50 nuts, which required restriction of the nut contribution equally from the 14% most fertile individuals to a maximum contribution of 0.74%. This increased the Ns from 149 to 201, while 85% of all nuts were included.
Upconverting nanoparticles (UCNPs) have recently shown great potential as contrast agents in biol... more Upconverting nanoparticles (UCNPs) have recently shown great potential as contrast agents in biological applications. In developing different UCNPs, the characterization of their quantum yield (QY) is a crucial issue, as the typically drastic decrease in QY for low excitation power densities can either impose a severe limitation or provide an opportunity in many applications. The power density dependence of the QY is governed by the competition between the energy transfer upconversion (ETU) rate and the linear decay rate in the depopulation of the intermediate state of the involved activator in the upconversion process. Here we show that the QYs of Yb(3+) sensitized two-photon upconversion emissions can be well characterized by the balancing power density, at which the ETU rate and the linear decay rate have equal contributions, and its corresponding QY. The results in this paper provide a method to fully describe the QY of upconverting nanoparticles for arbitrary excitation power densities, and is a fast and simple approach for assessing the applicability of UCNPs from the perspective of energy conversion.
In several forest tree breeding operations either backward or forward selection is used, although... more In several forest tree breeding operations either backward or forward selection is used, although a proper combination of both might be more advantageous. Using calculations based on quantitative genetic theory, comparisons were made between the relative merits of backward and forward selection for individual families. In backward selection the mother was chosen based on her offspring and in forward selection the best offspring was selected from the family consisting of the mother and her children. A range of heritabilities and selection inten- sities in natural forest and progeny test (the latter is a function of progeny size) were compared. It is the more favourable to select backward the higher the mother ranks. Depending on the combination of parameter values, backward selection was superior to forward selection for open pollinated progeny in 1% to 57% of the top ranking families. High intensity of selection in the forest, low herita- bility and small progeny size favoured backw...
... Dag Lindgren, Darius Danusevicˇius, and Ola Rosvall ... environmental variance (the variance ... more ... Dag Lindgren, Darius Danusevicˇius, and Ola Rosvall ... environmental variance (the variance components are as-sumed for the measured trait selected for (eg, height)); sAm is the standard deviation in breeding value of the se-lected individuals for the target trait at mature age ...
ABSTRACT A method of finding the optimal selected proportions within large individual families is... more ABSTRACT A method of finding the optimal selected proportions within large individual families is derived. The method identifies family contributions which maximize genetic gain at a given diversity and selected proportion (or rather suggests an optimum combination of these three entities). The population considered is a number of large unrelated families with normal within-family variation. The optimally selected proportion of members from a family is dependent on the average breeding value of the family, the average selected proportion, the diversity, the heritability and the intraclass correlation for the family type. A numerical example is given.
The effective number of clones (Nc) wasestimated for 255 conifer clonal seed orchards in Finland,... more The effective number of clones (Nc) wasestimated for 255 conifer clonal seed orchards in Finland, Korea, andSweden, based on the variation in the number of ramets among clones. Themean census number of clones (N) varied from 70, in 13 KoreanPinus koraiensis seed orchards, to 139 in 176 Finnish Pinussylvestris seed orchards. The mean effective number of clones(Nc) was 66, with
ABSTRACT Genetic relationship within a population can be measured by average coancestry. This ca... more ABSTRACT Genetic relationship within a population can be measured by average coancestry. This can also be expressed as an effective number which represents the relative genetic diversity of the population. The goal of breeding can be formulated to maximise genetic value minus average coancestry times a constant (the “penalty constant”). An iterative search algorithm can then be used to find the best selections for meeting this goal. Two such algorithms, one for a fixed number of selections and the other for a variable optimum number, were applied to select a mixture of field-tested Norway spruce clones with known parents. The results were compared with those from the conventional method of restricting parental contributions to the selected population as a means to control diversity. Coancestry-adjusted selection always yielded more gain than restricted selection at a given effective population size (except under circumstances where the methods were equivalent). Expressed another way, at any given level of gain, coancestry-adjusted selection maintained a larger effective population size than did restricted selection. The relative superiority of coancestry-adjusted selection declined when the effective population size approached the lowest value, that at which no penalty or restriction was applied. The method was extended by the second search algorithm to optimise the selected number of clones. The optimal number of clones can be rather large when diversity is heavily valued, but the reduction in genetic gain becomes large.
The value of a mixture of genetic entries present in different proportions is defined. A measure ... more The value of a mixture of genetic entries present in different proportions is defined. A measure of the disadvantage of reduced diversity is defined as the sum of the squares of the proportions of the different entries. An algorithm for maximizing genetic gain of the mixture under the constraint of a constant disadvantage is developed. The optimal deployment strategy is one that lets the proportion of the genetic entries be linearly dependent on their genetic value. By use of rankits as entries for genetic values, optimal solutions for deployment were calculated for a range of values of available entries (from 10 to 5,000) and preset diversity-related disadvantage-factors (the preset values correspond to mixtures of between 2 and 100 entries in identical proportions). The values are tabulated so they can be used by breeders. The superiority of the proposed strategy increases with the proportion of the available entries which are selected. In the situation that around half would have been selected if truncation selection was applied, the improvement in genetic gain compared to classical truncation selection is up to 18%. Thus, considerable improvements in gain are possible without any sacrifice in diversity. Applications are discussed with particular reference to clonal forestry.
ABSTRACT A theory on the balance between gene diversity and level of nut collection was developed... more ABSTRACT A theory on the balance between gene diversity and level of nut collection was developed and applied to Danish hazelnut (Corylus avellana L.) populations. By controlling female fertility based on the power function F(x)=xa, a trade-off between equalizing maternal contribution and obtaining an acceptable amount of nuts was achieved, and gene diversity during the initial phase of mobilizing the natural gene pool could be managed. Constraints on nut production could be made on maternal proportion as both lower and upper bounds. For a case involving the collection of hazelnuts from 264 individuals, the status number (Ns) was estimated to be 149 based on female contribution if all nuts were collected and used. Higher status numbers could be obtained by balancing the number of nuts collected per tree, but such an increase in the status number would result in a substantial loss of nut production. It was decided to truncate the progeny size at 50 nuts, which required restriction of the nut contribution equally from the 14% most fertile individuals to a maximum contribution of 0.74%. This increased the Ns from 149 to 201, while 85% of all nuts were included.
Upconverting nanoparticles (UCNPs) have recently shown great potential as contrast agents in biol... more Upconverting nanoparticles (UCNPs) have recently shown great potential as contrast agents in biological applications. In developing different UCNPs, the characterization of their quantum yield (QY) is a crucial issue, as the typically drastic decrease in QY for low excitation power densities can either impose a severe limitation or provide an opportunity in many applications. The power density dependence of the QY is governed by the competition between the energy transfer upconversion (ETU) rate and the linear decay rate in the depopulation of the intermediate state of the involved activator in the upconversion process. Here we show that the QYs of Yb(3+) sensitized two-photon upconversion emissions can be well characterized by the balancing power density, at which the ETU rate and the linear decay rate have equal contributions, and its corresponding QY. The results in this paper provide a method to fully describe the QY of upconverting nanoparticles for arbitrary excitation power densities, and is a fast and simple approach for assessing the applicability of UCNPs from the perspective of energy conversion.
In several forest tree breeding operations either backward or forward selection is used, although... more In several forest tree breeding operations either backward or forward selection is used, although a proper combination of both might be more advantageous. Using calculations based on quantitative genetic theory, comparisons were made between the relative merits of backward and forward selection for individual families. In backward selection the mother was chosen based on her offspring and in forward selection the best offspring was selected from the family consisting of the mother and her children. A range of heritabilities and selection inten- sities in natural forest and progeny test (the latter is a function of progeny size) were compared. It is the more favourable to select backward the higher the mother ranks. Depending on the combination of parameter values, backward selection was superior to forward selection for open pollinated progeny in 1% to 57% of the top ranking families. High intensity of selection in the forest, low herita- bility and small progeny size favoured backw...
... Dag Lindgren, Darius Danusevicˇius, and Ola Rosvall ... environmental variance (the variance ... more ... Dag Lindgren, Darius Danusevicˇius, and Ola Rosvall ... environmental variance (the variance components are as-sumed for the measured trait selected for (eg, height)); sAm is the standard deviation in breeding value of the se-lected individuals for the target trait at mature age ...
ABSTRACT A method of finding the optimal selected proportions within large individual families is... more ABSTRACT A method of finding the optimal selected proportions within large individual families is derived. The method identifies family contributions which maximize genetic gain at a given diversity and selected proportion (or rather suggests an optimum combination of these three entities). The population considered is a number of large unrelated families with normal within-family variation. The optimally selected proportion of members from a family is dependent on the average breeding value of the family, the average selected proportion, the diversity, the heritability and the intraclass correlation for the family type. A numerical example is given.
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Papers by D. Lindgren