Michael Stoehr - Profile on Academia.edu (original) (raw)
Papers by Michael Stoehr
Understanding the molecular basis of adaptive traits is a major interest in conservation and popu... more Understanding the molecular basis of adaptive traits is a major interest in conservation and population genetics. In commercial species, such as several conifers, it is also interesting for operational breeding. In this chapter, we provide a state-of-the-art view on candidate gene research, from general estimates of nucleotide diversity and recombination to new-generation neutrality tests and association genetics methodologies. Levels of nucleotide diversity in conifers are substantial, although lower than expected given their life-history traits. In addition, linkage disequilibrium seems to decay rapidly in this group of species, at least within genes that are not submitted to natural selection. These two facts makes genetic association studies appealing in conifers, as significant associations may correspond to the actual causal polymorphisms. Population genomic methods also seem appropriate in conifers, in particular for those species with accused population genetic structure and strong response to environmental gradients. New-generation neutrality tests, outlier loci detection methods and genotype/phenotype association studies have revealed various candidate genes and single nucleotide polymorphisms underlying different adaptive phenotypes, despite potential confounding effects of demographical and historical processes. Finally, perspectives about future genomic research in conifers are provided, including its application for conservation and breeding.
New Forest, 1995
Application . As seed orchards become older, increasing tree heights make orchard management prac... more Application . As seed orchards become older, increasing tree heights make orchard management practices more difficult and expensive . Crown pruning is often used to lower the crowns and possibly stimulate floral induction . In this study long-term cone yields were compared for control and crown-pruned trees . Cone yield averages over 5 years were lower in pruned trees, but this effect was offset by benefits associated with a reduction in tree height . A maximum of 40% of the live crown can be removed without long-term negative effects on cone productivity.
Evaluating Supplemental Mass Pollination Efficacy in a Lodgepole Pine Orchard in British Columbia using Chloroplast DNA Markers
New Forest, 2006
Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex... more Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard in southern British Columbia was studied by employing four chloroplast DNA (cpDNA) markers to determine fertilization success of 10 pollen parents. SMP was conducted operationally with a bulked pollen mix twice during peak receptivity in the seed orchard. Fertilization success
Pollen contamination effects on progeny from an off-site Douglas-fir seed orchard
Can J Forest Res, 1994
Anomalous Solitary Flowers on Anther-Derived Plants of Populus maximowiczii
American Journal of Botany, Apr 1, 1988
Theoretical and Applied Genetics, 1997
Concerns over the reductionist nature of the domestication of forest-tree species focus on the po... more Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia "interior" spruce (Picea glauca x engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone's seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow (N. = 7). Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci (%P = 64.7%) while the expected hetrozygosity (H e) (0.207 vs 0.2 10) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations' rare alleles (P < 0.007) were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen Communicated by P. M. A. Tigerstedt M. U. Stoehr (^) Glyn Road Research Station, Ministry of Forests,
We surveyed genetic variation in chloroplast DNA (cpDNA) of Douglas-fir (Pseudotsuga menziesii (M... more We surveyed genetic variation in chloroplast DNA (cpDNA) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) from the coastal and interior regions of British Columbia. Restriction digestion of a 1765 base pair (bp) region of the cpDNA molecule revealed 3 1 distinct haplotypes in a total of 58 trees. A total of 15 haplotypes were observed in coastal trees while 16 haplotypes were detected in trees from the interior of British Columbia. Gene diversity was high overall and slightly higher in the coastal sample 0.95 (SD 0.02) than in the interior sample 0.88 (SD 0.05). The coastal and the interior populations were significantly differentiated from each other as none of the cpDNA haplotypes were shared between the regions. This suggests that gene flow from pollen dispersal is restricted between these two regions, and that possibly the two regions were colonized by different sources following the end of the Fraser glaciation approximately 10,000 years before the present time. The simple method developed for assaying cpDNA heterogeneity in Douglas-fir will be useful for further study of biogeography and population structure of the species and for monitoring pollen flow in seed orchards.
Seed genetic quality affects reforestation success and plantation value. This is recognized in th... more Seed genetic quality affects reforestation success and plantation value. This is recognized in the Silviculture Practices Regulations of the Forest Practices Code Act of British Columbia, which require that available seed sources of the highest genetic quality be used to reforest Crown land. This report describes procedures for rating the genetic quality of seed orchard seedlots.
An experiment was conducted to test pollen competition as reflected in the reproductive success o... more An experiment was conducted to test pollen competition as reflected in the reproductive success of individual pollen lots in two polymixes in Douglas-fir (Pseudotsuga rnenziesii (Mirb.) Franco). One polymix contained six pollen lots in equal proportion by weight, the other polymix was formulated using the same six pollen lots but in inversely proportional amounts to their viability. Pollen lot viability was measured as respiration (oxygen uptake). Reproductive success of individual male parents (pollen lots) was determined following control pollinations using both polymixes separately on six female clones. The paternity analysis was carried out using a chloroplast DNA marker amplified by the polymerase chain reaction (PCR) in total DNA extracts of embryos dissected from mature seed, allowing the identification of the male parent in "polycrossed" seed. Average number of filled seed per cone was not affected by the two polymixes, but the reproductive success of individual ma...
Methods in molecular biology (Clifton, N.J.), 2011
Artificial regeneration of forests through planting requires high quantities of quality seeds for... more Artificial regeneration of forests through planting requires high quantities of quality seeds for growing vigorous seedlings. These seedlings are raised in nurseries, where germination capacity (GC) and speed are the most important germination parameters. Germination performance is enhanced by prescribing species-specific dormancy-breaking treatments to individual seedlots in bare-root and container nurseries. For most conifer species in British Columbia, the dormancy-breaking treatments and germination conditions have been worked out, but fine-tuning and optimization could improve germination capacity and speed of germination. Implications of inter- and intra-species variations in germination behaviour and seed quality and their influence on the development of unintentional directional selection of specific genotypes are discussed. The potential of molecular and genomics approaches to understand the underlying biology of seed germination-related problems is also discussed.
Quantifying safe seed transfer distance and impacts of tree breeding on adaptation
Forest Ecology and Management, 2014
ABSTRACT Tree seed zones that are too large can compromise forest plantation health and productiv... more ABSTRACT Tree seed zones that are too large can compromise forest plantation health and productivity due to maladaptation arising from some populations being transferred long distances, whereas tree seed zones that are too small can result in unwarranted seed collections or excessive numbers of breeding zones. There has been little discussion, however, regarding the development and use of transfer functions for quantifying critical (i.e., safe) seed transfer distance (CSTD) or how artificial selection might affect CSTD. Using data from a large, multi-site provenance test for Douglas-fir and Interior spruce containing both genetically selected and wildstand seed sources, we illustrate an approach to quantify CSTD using Euclidean climate transfer distance modeled with a half-normal transfer function. A wide range of CSTDs was calculated and most transfer functions showed that selected seed sources were considerably taller than wildstand seed sources when transferred short or medium climate distances. Contrarily, selected seed sources were shorter than wildstand seed sources when transferred long climate distances. CSTDs were shorter for Douglas-fir than for spruce, and shorter when calculated using height rather than survival as the transfer function response variable. These findings suggest that (1) unfavorable changes in adaptation due to artificial selection will be observable only when seed is transferred considerably beyond the CSTD; (2) differences in adaptation between selected and wildstand seed classes may not warrant separate seed transfer guidelines for these seed classes; (3) British Columbia’s Douglas-fir and Interior spruce breeding programs are generating significant height gain; (4) methods presented here produce logical transfer functions that can be used to calculate reliable site-specific CSTDs; (5) use of conservative (short) CSTDs may be advisable when tests are young; and (6) provenance tests should be located in disparate climates.
Annals of Forest Science, 2014
& Context The effects of inbreeding on growth traits have been studied and are fairly well unders... more & Context The effects of inbreeding on growth traits have been studied and are fairly well understood in young conifers. However, in trees approaching mid-rotation, this information is not widely available at present. & Aim The aim of this study is to assess inbreeding depression in mid-rotation coastal Douglas-fir in growth traits, survival, and wood density. & Methods Several levels of inbreeding were created in coastal Douglas-fir, using a nine-clone founder population to produce 148 families with varying levels of inbreeding ranging from f=0 (outcrossed) to f=0.5 (selfed). The trees were planted in 1987 on two farm-field sites in coastal BC. Here, we report effects of inbreeding in height, diameter, tree volume, survival, and wood density in 26-year-old trees. & Results Previous results obtained from this test population showed negative near linear effects with levels of inbreeding in seed production, nursery growth performance, and growth traits in the field assessed at age 10. At age 26, inbreeding depression was highest in survival, ranging from 20 to 80 % for f=0.125 and f=0.5, respectively. In contrast, the most severe inbreeding depression among the three levels of inbreeding was only 4 % for wood density at f=0.5 (selfing). Inbreeding depression in height, diameter at breast height (dbh), and volume increased linearly from f=0 to f=0.25, then leveled off. & Conclusion Founder genotypes had varied responses to inbreeding as parental breeding values across inbreeding levels were inconsistent (in magnitude, sign, and trait). No differences in levels of inbreeding depression were found between full-sib matings and parent-offspring matings. These findings have implications for the testing of parents within sublines, where inbreeding is accumulated in sublines. However, since parents respond differently to levels of inbreeding, their performance may not be well correlated to their quality as outcrossing parents.
Tree Genetics & Genomes, 2007
Sublines are used in the third-generation breeding and testing of coastal Douglas-fir in British ... more Sublines are used in the third-generation breeding and testing of coastal Douglas-fir in British Columbia, with the original intent of selecting only one genotype per subline for production populations (e.g., seed orchards) to eliminate relatedness among parents (therein called "1/ SL"). We evaluated three additional selection scenarios that did not consider the subline structure. One of the scenarios strictly selected on the basis of the highest breeding values of the trees ("TOP"); another scenario used the TOP selections, but assigned the number of ramets per selection proportionally to the selection breeding value ("LIND"); lastly, a simulated annealing technique was applied to maximize gain under explicit constraints on coancestry ("OPTS"). All three alternative selection scenarios resulted in some relatedness and coancestry among selections, but the last two provided increases in average breeding values compared to those obtained by the 1/SL scenario. Effective population sizes (and consequently inbreeding coefficients) varied among the three selection scenarios. Effects of the various selections on merchantable volume at rotation age were determined using a linear regression model based on an individual tree model (TASS), which was first run to determine the relationship between merchantable volume and inbreeding (f). LIND and TOP selections yielded the highest breeding values but, due to the increased coancestry among selections, paid a penalty in the merchantable volume determination. OPTS maximized merchantable volume at rotation age 60 after including more than 13 selections with an increase of around 3% over that obtained by the 1/SL selection scenario, with an associated increase in Ne of 50%. Other implications of the three alternative selection scenarios are discussed.
Ectomycorrhizal fungal maladaptation and growth reductions associated with assisted migration of Douglas-fir
The New phytologist, Jan 26, 2015
Climatic adaptations are the foundation of conifer genecology, but populations also display varia... more Climatic adaptations are the foundation of conifer genecology, but populations also display variation in traits for nitrogen (N) utilization, along with some heritable specificity for ectomycorrhizal fungi (EMF). We examined soil and EMF influences on assisted migration of Douglas-fir (Pseudotsuga menziesii var. menziesii) by comparing two contrasting maritime populations planted up to 400 km northward in southwestern British Columbia. Soil N availability and host N status (via δ(15) N) were assessed across 12 maritime test sites, whereas EMF on local and introduced hosts were quantified by morphotyping with molecular analysis. Climatic transfer effects were only significant with soil N concentrations of test sites as a covariate, and illustrated how height growth was compromised for populations originating from relatively dry or cool maritime environments. We also found evidence for EMF maladaptation, where height declined by up to 15% with the extent of dissimilarity in EMF commun...
Tree Genetics & Genomes, 2005
A common garden study was conducted with seedlings of the interior spruce complex [Picea glauca (... more A common garden study was conducted with seedlings of the interior spruce complex [Picea glauca (Monch) Voss and Picea. engelmannii Parry and their hybrids], comparing seedling height growth using openpollinated orchard families and wild-stand (WS) families from the same breeding zone. Phenotypic variances of three bulked orchard seedlots and three WS seedlots did not differ. Orchard seedlots had generally higher withinfamily variance components than WS families. To examine year-to-year variation in orchard seedlots, three seedlots, composed of the same 18 orchard families collected in three different years, were evaluated in the same common garden study. Family mean heights within the three crop years were statistically not different; however, large rank changes in family mean heights and family variances were observed. This study shows that orchard seed derived from breeding programs does not reduce phenotypic variability in commercial plantations. In spite of the moderate to high selection intensities applied to the selection of orchard parents, large amounts of phenotypic variation are maintained because of the lack of coancestry in the orchard pollen cloud and large temporal variation in mating success and fecundity of the various parents contributing to the crop.
Theoretical and Applied Genetics, 1997
Concerns over the reductionist nature of the domestication of forest-tree species focus on the po... more Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia "interior" spruce (Picea glauca x engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone's seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow (N. = 7). Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci (%P = 64.7%) while the expected hetrozygosity (H e) (0.207 vs 0.2 10) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations' rare alleles (P < 0.007) were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen Communicated by P. M. A. Tigerstedt M. U. Stoehr (^) Glyn Road Research Station, Ministry of Forests,
Evaluating Supplemental Mass Pollination Efficacy in a Lodgepole Pine Orchard in British Columbia using Chloroplast DNA Markers
New Forests, 2006
Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex... more Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard in southern British Columbia was studied by employing four chloroplast DNA (cpDNA) markers to determine fertilization success of 10 pollen parents. SMP was conducted operationally with a bulked pollen mix twice during peak receptivity in the seed orchard. Fertilization success
Understanding the molecular basis of adaptive traits is a major interest in conservation and popu... more Understanding the molecular basis of adaptive traits is a major interest in conservation and population genetics. In commercial species, such as several conifers, it is also interesting for operational breeding. In this chapter, we provide a state-of-the-art view on candidate gene research, from general estimates of nucleotide diversity and recombination to new-generation neutrality tests and association genetics methodologies. Levels of nucleotide diversity in conifers are substantial, although lower than expected given their life-history traits. In addition, linkage disequilibrium seems to decay rapidly in this group of species, at least within genes that are not submitted to natural selection. These two facts makes genetic association studies appealing in conifers, as significant associations may correspond to the actual causal polymorphisms. Population genomic methods also seem appropriate in conifers, in particular for those species with accused population genetic structure and strong response to environmental gradients. New-generation neutrality tests, outlier loci detection methods and genotype/phenotype association studies have revealed various candidate genes and single nucleotide polymorphisms underlying different adaptive phenotypes, despite potential confounding effects of demographical and historical processes. Finally, perspectives about future genomic research in conifers are provided, including its application for conservation and breeding.
New Forest, 1995
Application . As seed orchards become older, increasing tree heights make orchard management prac... more Application . As seed orchards become older, increasing tree heights make orchard management practices more difficult and expensive . Crown pruning is often used to lower the crowns and possibly stimulate floral induction . In this study long-term cone yields were compared for control and crown-pruned trees . Cone yield averages over 5 years were lower in pruned trees, but this effect was offset by benefits associated with a reduction in tree height . A maximum of 40% of the live crown can be removed without long-term negative effects on cone productivity.
Evaluating Supplemental Mass Pollination Efficacy in a Lodgepole Pine Orchard in British Columbia using Chloroplast DNA Markers
New Forest, 2006
Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex... more Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard in southern British Columbia was studied by employing four chloroplast DNA (cpDNA) markers to determine fertilization success of 10 pollen parents. SMP was conducted operationally with a bulked pollen mix twice during peak receptivity in the seed orchard. Fertilization success
Pollen contamination effects on progeny from an off-site Douglas-fir seed orchard
Can J Forest Res, 1994
Anomalous Solitary Flowers on Anther-Derived Plants of Populus maximowiczii
American Journal of Botany, Apr 1, 1988
Theoretical and Applied Genetics, 1997
Concerns over the reductionist nature of the domestication of forest-tree species focus on the po... more Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia "interior" spruce (Picea glauca x engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone's seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow (N. = 7). Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci (%P = 64.7%) while the expected hetrozygosity (H e) (0.207 vs 0.2 10) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations' rare alleles (P < 0.007) were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen Communicated by P. M. A. Tigerstedt M. U. Stoehr (^) Glyn Road Research Station, Ministry of Forests,
We surveyed genetic variation in chloroplast DNA (cpDNA) of Douglas-fir (Pseudotsuga menziesii (M... more We surveyed genetic variation in chloroplast DNA (cpDNA) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) from the coastal and interior regions of British Columbia. Restriction digestion of a 1765 base pair (bp) region of the cpDNA molecule revealed 3 1 distinct haplotypes in a total of 58 trees. A total of 15 haplotypes were observed in coastal trees while 16 haplotypes were detected in trees from the interior of British Columbia. Gene diversity was high overall and slightly higher in the coastal sample 0.95 (SD 0.02) than in the interior sample 0.88 (SD 0.05). The coastal and the interior populations were significantly differentiated from each other as none of the cpDNA haplotypes were shared between the regions. This suggests that gene flow from pollen dispersal is restricted between these two regions, and that possibly the two regions were colonized by different sources following the end of the Fraser glaciation approximately 10,000 years before the present time. The simple method developed for assaying cpDNA heterogeneity in Douglas-fir will be useful for further study of biogeography and population structure of the species and for monitoring pollen flow in seed orchards.
Seed genetic quality affects reforestation success and plantation value. This is recognized in th... more Seed genetic quality affects reforestation success and plantation value. This is recognized in the Silviculture Practices Regulations of the Forest Practices Code Act of British Columbia, which require that available seed sources of the highest genetic quality be used to reforest Crown land. This report describes procedures for rating the genetic quality of seed orchard seedlots.
An experiment was conducted to test pollen competition as reflected in the reproductive success o... more An experiment was conducted to test pollen competition as reflected in the reproductive success of individual pollen lots in two polymixes in Douglas-fir (Pseudotsuga rnenziesii (Mirb.) Franco). One polymix contained six pollen lots in equal proportion by weight, the other polymix was formulated using the same six pollen lots but in inversely proportional amounts to their viability. Pollen lot viability was measured as respiration (oxygen uptake). Reproductive success of individual male parents (pollen lots) was determined following control pollinations using both polymixes separately on six female clones. The paternity analysis was carried out using a chloroplast DNA marker amplified by the polymerase chain reaction (PCR) in total DNA extracts of embryos dissected from mature seed, allowing the identification of the male parent in "polycrossed" seed. Average number of filled seed per cone was not affected by the two polymixes, but the reproductive success of individual ma...
Methods in molecular biology (Clifton, N.J.), 2011
Artificial regeneration of forests through planting requires high quantities of quality seeds for... more Artificial regeneration of forests through planting requires high quantities of quality seeds for growing vigorous seedlings. These seedlings are raised in nurseries, where germination capacity (GC) and speed are the most important germination parameters. Germination performance is enhanced by prescribing species-specific dormancy-breaking treatments to individual seedlots in bare-root and container nurseries. For most conifer species in British Columbia, the dormancy-breaking treatments and germination conditions have been worked out, but fine-tuning and optimization could improve germination capacity and speed of germination. Implications of inter- and intra-species variations in germination behaviour and seed quality and their influence on the development of unintentional directional selection of specific genotypes are discussed. The potential of molecular and genomics approaches to understand the underlying biology of seed germination-related problems is also discussed.
Quantifying safe seed transfer distance and impacts of tree breeding on adaptation
Forest Ecology and Management, 2014
ABSTRACT Tree seed zones that are too large can compromise forest plantation health and productiv... more ABSTRACT Tree seed zones that are too large can compromise forest plantation health and productivity due to maladaptation arising from some populations being transferred long distances, whereas tree seed zones that are too small can result in unwarranted seed collections or excessive numbers of breeding zones. There has been little discussion, however, regarding the development and use of transfer functions for quantifying critical (i.e., safe) seed transfer distance (CSTD) or how artificial selection might affect CSTD. Using data from a large, multi-site provenance test for Douglas-fir and Interior spruce containing both genetically selected and wildstand seed sources, we illustrate an approach to quantify CSTD using Euclidean climate transfer distance modeled with a half-normal transfer function. A wide range of CSTDs was calculated and most transfer functions showed that selected seed sources were considerably taller than wildstand seed sources when transferred short or medium climate distances. Contrarily, selected seed sources were shorter than wildstand seed sources when transferred long climate distances. CSTDs were shorter for Douglas-fir than for spruce, and shorter when calculated using height rather than survival as the transfer function response variable. These findings suggest that (1) unfavorable changes in adaptation due to artificial selection will be observable only when seed is transferred considerably beyond the CSTD; (2) differences in adaptation between selected and wildstand seed classes may not warrant separate seed transfer guidelines for these seed classes; (3) British Columbia’s Douglas-fir and Interior spruce breeding programs are generating significant height gain; (4) methods presented here produce logical transfer functions that can be used to calculate reliable site-specific CSTDs; (5) use of conservative (short) CSTDs may be advisable when tests are young; and (6) provenance tests should be located in disparate climates.
Annals of Forest Science, 2014
& Context The effects of inbreeding on growth traits have been studied and are fairly well unders... more & Context The effects of inbreeding on growth traits have been studied and are fairly well understood in young conifers. However, in trees approaching mid-rotation, this information is not widely available at present. & Aim The aim of this study is to assess inbreeding depression in mid-rotation coastal Douglas-fir in growth traits, survival, and wood density. & Methods Several levels of inbreeding were created in coastal Douglas-fir, using a nine-clone founder population to produce 148 families with varying levels of inbreeding ranging from f=0 (outcrossed) to f=0.5 (selfed). The trees were planted in 1987 on two farm-field sites in coastal BC. Here, we report effects of inbreeding in height, diameter, tree volume, survival, and wood density in 26-year-old trees. & Results Previous results obtained from this test population showed negative near linear effects with levels of inbreeding in seed production, nursery growth performance, and growth traits in the field assessed at age 10. At age 26, inbreeding depression was highest in survival, ranging from 20 to 80 % for f=0.125 and f=0.5, respectively. In contrast, the most severe inbreeding depression among the three levels of inbreeding was only 4 % for wood density at f=0.5 (selfing). Inbreeding depression in height, diameter at breast height (dbh), and volume increased linearly from f=0 to f=0.25, then leveled off. & Conclusion Founder genotypes had varied responses to inbreeding as parental breeding values across inbreeding levels were inconsistent (in magnitude, sign, and trait). No differences in levels of inbreeding depression were found between full-sib matings and parent-offspring matings. These findings have implications for the testing of parents within sublines, where inbreeding is accumulated in sublines. However, since parents respond differently to levels of inbreeding, their performance may not be well correlated to their quality as outcrossing parents.
Tree Genetics & Genomes, 2007
Sublines are used in the third-generation breeding and testing of coastal Douglas-fir in British ... more Sublines are used in the third-generation breeding and testing of coastal Douglas-fir in British Columbia, with the original intent of selecting only one genotype per subline for production populations (e.g., seed orchards) to eliminate relatedness among parents (therein called "1/ SL"). We evaluated three additional selection scenarios that did not consider the subline structure. One of the scenarios strictly selected on the basis of the highest breeding values of the trees ("TOP"); another scenario used the TOP selections, but assigned the number of ramets per selection proportionally to the selection breeding value ("LIND"); lastly, a simulated annealing technique was applied to maximize gain under explicit constraints on coancestry ("OPTS"). All three alternative selection scenarios resulted in some relatedness and coancestry among selections, but the last two provided increases in average breeding values compared to those obtained by the 1/SL scenario. Effective population sizes (and consequently inbreeding coefficients) varied among the three selection scenarios. Effects of the various selections on merchantable volume at rotation age were determined using a linear regression model based on an individual tree model (TASS), which was first run to determine the relationship between merchantable volume and inbreeding (f). LIND and TOP selections yielded the highest breeding values but, due to the increased coancestry among selections, paid a penalty in the merchantable volume determination. OPTS maximized merchantable volume at rotation age 60 after including more than 13 selections with an increase of around 3% over that obtained by the 1/SL selection scenario, with an associated increase in Ne of 50%. Other implications of the three alternative selection scenarios are discussed.
Ectomycorrhizal fungal maladaptation and growth reductions associated with assisted migration of Douglas-fir
The New phytologist, Jan 26, 2015
Climatic adaptations are the foundation of conifer genecology, but populations also display varia... more Climatic adaptations are the foundation of conifer genecology, but populations also display variation in traits for nitrogen (N) utilization, along with some heritable specificity for ectomycorrhizal fungi (EMF). We examined soil and EMF influences on assisted migration of Douglas-fir (Pseudotsuga menziesii var. menziesii) by comparing two contrasting maritime populations planted up to 400 km northward in southwestern British Columbia. Soil N availability and host N status (via δ(15) N) were assessed across 12 maritime test sites, whereas EMF on local and introduced hosts were quantified by morphotyping with molecular analysis. Climatic transfer effects were only significant with soil N concentrations of test sites as a covariate, and illustrated how height growth was compromised for populations originating from relatively dry or cool maritime environments. We also found evidence for EMF maladaptation, where height declined by up to 15% with the extent of dissimilarity in EMF commun...
Tree Genetics & Genomes, 2005
A common garden study was conducted with seedlings of the interior spruce complex [Picea glauca (... more A common garden study was conducted with seedlings of the interior spruce complex [Picea glauca (Monch) Voss and Picea. engelmannii Parry and their hybrids], comparing seedling height growth using openpollinated orchard families and wild-stand (WS) families from the same breeding zone. Phenotypic variances of three bulked orchard seedlots and three WS seedlots did not differ. Orchard seedlots had generally higher withinfamily variance components than WS families. To examine year-to-year variation in orchard seedlots, three seedlots, composed of the same 18 orchard families collected in three different years, were evaluated in the same common garden study. Family mean heights within the three crop years were statistically not different; however, large rank changes in family mean heights and family variances were observed. This study shows that orchard seed derived from breeding programs does not reduce phenotypic variability in commercial plantations. In spite of the moderate to high selection intensities applied to the selection of orchard parents, large amounts of phenotypic variation are maintained because of the lack of coancestry in the orchard pollen cloud and large temporal variation in mating success and fecundity of the various parents contributing to the crop.
Theoretical and Applied Genetics, 1997
Concerns over the reductionist nature of the domestication of forest-tree species focus on the po... more Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia "interior" spruce (Picea glauca x engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone's seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow (N. = 7). Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci (%P = 64.7%) while the expected hetrozygosity (H e) (0.207 vs 0.2 10) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations' rare alleles (P < 0.007) were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen Communicated by P. M. A. Tigerstedt M. U. Stoehr (^) Glyn Road Research Station, Ministry of Forests,
Evaluating Supplemental Mass Pollination Efficacy in a Lodgepole Pine Orchard in British Columbia using Chloroplast DNA Markers
New Forests, 2006
Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex... more Supplemental mass pollination (SMP) success in a grafted lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed orchard in southern British Columbia was studied by employing four chloroplast DNA (cpDNA) markers to determine fertilization success of 10 pollen parents. SMP was conducted operationally with a bulked pollen mix twice during peak receptivity in the seed orchard. Fertilization success