Status number is a measure of effective population size that is based on current relatedness only... more Status number is a measure of effective population size that is based on current relatedness only. Formulae are developed for group coancestry (=average coancestry) and status number for seed orchard crops. The formulae consider (1) differences in reproductive success among orchard genotypes, (2) relatedness between pairs of orchard genotypes, (3) inbreeding of orchard genotypes, (4) influence of pollen contamination (considering its relatedness both to itself and to the genotypes in the orchard), and (5) gender differences and sexual asymmetries of orchard genotypes. Properties of status number and other measures of effective number are discussed. They may refer to rate or state, to the reference population or the development of an idealized population, and to different moments in the sexual cycle.
Proceedings of the 16th IFAC World Congress, 2005, 2005
This paper proposes advanced visualization and interaction techniques as a support for the analys... more This paper proposes advanced visualization and interaction techniques as a support for the analysis of system identification data. Non-linear or timedependent dynamics often leave a significant residual with linear, time-invariant models. The structure of this residual is decisive for the subsequent modelling and by visually analysing the data the modeller may gain a deeper insight into its structure than can be gained using only standard correlation analysis. Copyright c 2005 IFAC
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
Self-pollen seldom results in vital genotypes and can thus be regarded as unimportant. Large-size... more Self-pollen seldom results in vital genotypes and can thus be regarded as unimportant. Large-sized clones (clones with many ramets) are more exposed to self-pollen and spread more self-pollen and thus contribute relatively less than small-sized clones. The size of clones required to maximize genetic gain at given diversity, considering that only outcrossing contributes to successful gametes, was derived for tested clones intended to establish a Norway spruce (Picea abies) seed orchard. The derived optimal deployment was compared with linear deployment according to Lindgren and Matheson (Silvae Genet 35:173-177, 1986), where the size of a clone is deployed proportional to its breeding value. The study covered a range of effective numbers between 5 and 50. The results suggest that linear deployment is a good approximation to optimal deployment when only outcrossing is considered. The difference between the two strategies is decreased by increasing clone number and is negligible except at low effective numbers.
Bulk seedlots of two unpedigreed multiprovenance seed production areas (SPAs) each of Eucalyptus ... more Bulk seedlots of two unpedigreed multiprovenance seed production areas (SPAs) each of Eucalyptus camaldulensis and Eucalyptus tereticornis and one pedigreed seedling seed orchard (SSO) of E. tereticornis were planted in genetic gain trials at three southern Indian trial sites. At the time of seed collection, fewer than 30% trees flowered in these orchards, except in one E. camaldulensis SPA where 73% of the trees flowered, which had an estimated outcrossing rate of 86%. The E. tereticornis SSO was dominated by pollen from five highly fecund families of the Indian Mysore gum land race, which contributed 59% of the fruits produced. The SPA and SSO seedlots were compared with a bulked natural-provenance seedlot of E. camaldulensis (Morehead, Laura, and Kennedy Rivers, Queensland), another natural-provenance seedlot (Petford, Queensland), commercial eucalypt clones at two sites, and a Mysore gum seedlot at one site. At 3 years, progeny from all the four SPAs displayed good survival (79-93%) and performance similar to that of the natural provenances and the commercial clones. Progeny from the E. tereticornis SSO had significantly lower growth (at two sites) and lower survival at all three test sites. The Mysore gum seedlot displayed high fecundity and lower growth but better survival than the SSO progeny. Seed orchard genetic composition and flowering contributions thus affected progeny performance and the extent to which orchard genetic diversity was captured in the progeny. SPA progeny displayed greater fecundity than the natural provenances, indicating a response to selection for fertility.
Chloroplast DNA (cpDNA) restriction analysis was used to classify five reforestation seedlots as ... more Chloroplast DNA (cpDNA) restriction analysis was used to classify five reforestation seedlots as to species. The material included two Sitka spruce (Picea sitchensis (Bong.) Carr.), one white spruce (P. glauca (Moench) Voss) from interior British Columbia, and two putative hybrid seedlots from the coast-interior introgression zone in British Columbia. The cpDNA patterns generated by Bam-HI and Bcl-I from individual trees of Sitka spruce, white spruce, western white spruce (P. glauca var. albertiana (S. Brown)), and Engelmann spruce (P. engelmanni (Parry)) were species-specific. They were used as reference patterns for comparisons. In addition, two controlled crosses between white and Sitka spruce were analyzed to demonstrate the paternal inheritance of cpD-NA in spruces. The cpDNA restriction patterns for the five seedlots were obtained from composite samples of seedlings from each lot and compared to the typical cpD-NA patterns of each species. Restriction patterns for the two Sitka spruce seedlots agreed with those from the Sitka spruce tree, while patterns for the white spruce seedlots from British Columbia agreed with those from the white spruce tree, lacking evidence of any Engelmann spruce component in the sample. On the other hand, one putative hybrid seedlot showed cpDNA patterns similar to white spruce while the other showed fragments unique to both Sitka and white spruce, indicating that this was a hybrid seedlot. The analysis of cpDNA restriction polymorphism has proven to be an effective tool for classifying seedlots in regions of introgression. To our knowledge, these results provide the first demonstration of the use of cpDNA analysis for solving practical forestry problems.
This study compares population-wide positive assortative mating (PAM) with open-nucleus breeding ... more This study compares population-wide positive assortative mating (PAM) with open-nucleus breeding with an elite and main population when more effort is allocated to parents of the elite. A companion study showed that PAM is advantageous when testing effort is independent of parental value. In the present study, unbalanced testing was imposed by varying the number of crosses or the number of genotypes per cross. These unbalanced alternatives are compared with PAM, where the testing effort was varied so that better parents were mated more frequently. More effort allocated to parents of higher rank increased the additive effect and the additive variance and only slightly altered the group coancestry and inbreeding in the breeding population (BP) compared with completely balanced scenarios. Of particular interest to the breeder, large enhancement of the additive variance in the BP contributed to higher gains in the production population (PP). These simulations demonstrate that populationwide PAM leads to higher genetic gains compared with open-nucleus alternatives at any desired target level of diversity in the PP. This is true for both balanced (part I) and unbalanced distribution of testing effort (part II).
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.
Genetic gain and the gene diversity of seed crops from clonal seed orchards were formulated consi... more Genetic gain and the gene diversity of seed crops from clonal seed orchards were formulated considering genetic selection, fertility variation and pollen contamination, and compared for five different management strategies. Genetic response was studied as a function of orchard management tactics. Management variables included the proportion of clones left after genetic thinning and/or selective seed harvesting. Formulae were derived to calculate gene diversity (expressed as group coancestry or status number) based on the sex ratio in an orchard population. The influence of having different sets of clones serving as seed parents, or pollen parents, or as both, was analysed. In addition, the impact on genetic gain and the gene diversity of seed crops was studied quantitatively as a function of the quantity and quality of gene flow from outside the orchard. The negative impact of fertility variation among orchard genotypes on the gene diversity of the seed crop was quantified. Numerical examples were given to illustrate the impact of orchard management alternatives on genetic gain and gene diversity. The formulae and results of this study can be used for identifying favourable alternatives for the management of seed orchards.
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.
Status number is a measure of effective population size that is based on current relatedness only... more Status number is a measure of effective population size that is based on current relatedness only. Formulae are developed for group coancestry (=average coancestry) and status number for seed orchard crops. The formulae consider (1) differences in reproductive success among orchard genotypes, (2) relatedness between pairs of orchard genotypes, (3) inbreeding of orchard genotypes, (4) influence of pollen contamination (considering its relatedness both to itself and to the genotypes in the orchard), and (5) gender differences and sexual asymmetries of orchard genotypes. Properties of status number and other measures of effective number are discussed. They may refer to rate or state, to the reference population or the development of an idealized population, and to different moments in the sexual cycle.
Proceedings of the 16th IFAC World Congress, 2005, 2005
This paper proposes advanced visualization and interaction techniques as a support for the analys... more This paper proposes advanced visualization and interaction techniques as a support for the analysis of system identification data. Non-linear or timedependent dynamics often leave a significant residual with linear, time-invariant models. The structure of this residual is decisive for the subsequent modelling and by visually analysing the data the modeller may gain a deeper insight into its structure than can be gained using only standard correlation analysis. Copyright c 2005 IFAC
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
Self-pollen seldom results in vital genotypes and can thus be regarded as unimportant. Large-size... more Self-pollen seldom results in vital genotypes and can thus be regarded as unimportant. Large-sized clones (clones with many ramets) are more exposed to self-pollen and spread more self-pollen and thus contribute relatively less than small-sized clones. The size of clones required to maximize genetic gain at given diversity, considering that only outcrossing contributes to successful gametes, was derived for tested clones intended to establish a Norway spruce (Picea abies) seed orchard. The derived optimal deployment was compared with linear deployment according to Lindgren and Matheson (Silvae Genet 35:173-177, 1986), where the size of a clone is deployed proportional to its breeding value. The study covered a range of effective numbers between 5 and 50. The results suggest that linear deployment is a good approximation to optimal deployment when only outcrossing is considered. The difference between the two strategies is decreased by increasing clone number and is negligible except at low effective numbers.
Bulk seedlots of two unpedigreed multiprovenance seed production areas (SPAs) each of Eucalyptus ... more Bulk seedlots of two unpedigreed multiprovenance seed production areas (SPAs) each of Eucalyptus camaldulensis and Eucalyptus tereticornis and one pedigreed seedling seed orchard (SSO) of E. tereticornis were planted in genetic gain trials at three southern Indian trial sites. At the time of seed collection, fewer than 30% trees flowered in these orchards, except in one E. camaldulensis SPA where 73% of the trees flowered, which had an estimated outcrossing rate of 86%. The E. tereticornis SSO was dominated by pollen from five highly fecund families of the Indian Mysore gum land race, which contributed 59% of the fruits produced. The SPA and SSO seedlots were compared with a bulked natural-provenance seedlot of E. camaldulensis (Morehead, Laura, and Kennedy Rivers, Queensland), another natural-provenance seedlot (Petford, Queensland), commercial eucalypt clones at two sites, and a Mysore gum seedlot at one site. At 3 years, progeny from all the four SPAs displayed good survival (79-93%) and performance similar to that of the natural provenances and the commercial clones. Progeny from the E. tereticornis SSO had significantly lower growth (at two sites) and lower survival at all three test sites. The Mysore gum seedlot displayed high fecundity and lower growth but better survival than the SSO progeny. Seed orchard genetic composition and flowering contributions thus affected progeny performance and the extent to which orchard genetic diversity was captured in the progeny. SPA progeny displayed greater fecundity than the natural provenances, indicating a response to selection for fertility.
Chloroplast DNA (cpDNA) restriction analysis was used to classify five reforestation seedlots as ... more Chloroplast DNA (cpDNA) restriction analysis was used to classify five reforestation seedlots as to species. The material included two Sitka spruce (Picea sitchensis (Bong.) Carr.), one white spruce (P. glauca (Moench) Voss) from interior British Columbia, and two putative hybrid seedlots from the coast-interior introgression zone in British Columbia. The cpDNA patterns generated by Bam-HI and Bcl-I from individual trees of Sitka spruce, white spruce, western white spruce (P. glauca var. albertiana (S. Brown)), and Engelmann spruce (P. engelmanni (Parry)) were species-specific. They were used as reference patterns for comparisons. In addition, two controlled crosses between white and Sitka spruce were analyzed to demonstrate the paternal inheritance of cpD-NA in spruces. The cpDNA restriction patterns for the five seedlots were obtained from composite samples of seedlings from each lot and compared to the typical cpD-NA patterns of each species. Restriction patterns for the two Sitka spruce seedlots agreed with those from the Sitka spruce tree, while patterns for the white spruce seedlots from British Columbia agreed with those from the white spruce tree, lacking evidence of any Engelmann spruce component in the sample. On the other hand, one putative hybrid seedlot showed cpDNA patterns similar to white spruce while the other showed fragments unique to both Sitka and white spruce, indicating that this was a hybrid seedlot. The analysis of cpDNA restriction polymorphism has proven to be an effective tool for classifying seedlots in regions of introgression. To our knowledge, these results provide the first demonstration of the use of cpDNA analysis for solving practical forestry problems.
This study compares population-wide positive assortative mating (PAM) with open-nucleus breeding ... more This study compares population-wide positive assortative mating (PAM) with open-nucleus breeding with an elite and main population when more effort is allocated to parents of the elite. A companion study showed that PAM is advantageous when testing effort is independent of parental value. In the present study, unbalanced testing was imposed by varying the number of crosses or the number of genotypes per cross. These unbalanced alternatives are compared with PAM, where the testing effort was varied so that better parents were mated more frequently. More effort allocated to parents of higher rank increased the additive effect and the additive variance and only slightly altered the group coancestry and inbreeding in the breeding population (BP) compared with completely balanced scenarios. Of particular interest to the breeder, large enhancement of the additive variance in the BP contributed to higher gains in the production population (PP). These simulations demonstrate that populationwide PAM leads to higher genetic gains compared with open-nucleus alternatives at any desired target level of diversity in the PP. This is true for both balanced (part I) and unbalanced distribution of testing effort (part II).
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.
Genetic gain and the gene diversity of seed crops from clonal seed orchards were formulated consi... more Genetic gain and the gene diversity of seed crops from clonal seed orchards were formulated considering genetic selection, fertility variation and pollen contamination, and compared for five different management strategies. Genetic response was studied as a function of orchard management tactics. Management variables included the proportion of clones left after genetic thinning and/or selective seed harvesting. Formulae were derived to calculate gene diversity (expressed as group coancestry or status number) based on the sex ratio in an orchard population. The influence of having different sets of clones serving as seed parents, or pollen parents, or as both, was analysed. In addition, the impact on genetic gain and the gene diversity of seed crops was studied quantitatively as a function of the quantity and quality of gene flow from outside the orchard. The negative impact of fertility variation among orchard genotypes on the gene diversity of the seed crop was quantified. Numerical examples were given to illustrate the impact of orchard management alternatives on genetic gain and gene diversity. The formulae and results of this study can be used for identifying favourable alternatives for the management of seed orchards.
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