Balanced Breeding in a Grand Parent Perspective. - Consideration for Swedish Scots pine breeding Dag Lindgren Förädlingsutredningsmöte Uppsala 08- 05-14 Revised
Balanced Breeding in a Grand Parent Perspective.
- Consideration for Swedish Scots pine breeding
Dag Lindgren
Förädlingsutredningsmöte Uppsala 08-05-14
Revised
Study• Status: submitted, minor revision asked for, resubmitted
with authors Lindgren, Danusevicius and Rosvall.• Swedish pine breeding is target• SPM to simplify calculations• Cycle time is 18 years• Size of breeding population is a variable to be optimized,
not preset by the number of founders• Selection of good phenotypes in good families (“combined
selection”)• Reference (base line) is a phenotypic strategy (strategy 3),
which appear as one of the most promising of earlier considered strategies (paper in CJFR 2007 with participation of Gunnar Jansson).
• Variant of “strategy 5”
(…) (…)F1
SPM with parental balance(almost current Swedish program)
Grand parents (=founders), F0
Mating grand parentsSelect and mate 2 best sibs
(…) (…)F2
(…)(…)
2nd rank family
(…)
1st rank family
(…)
3rd rank family
(…)
nth rank family
(…)
Multiple SPMsGrandparents
=founders
Green trees show pedigree
F0
F1
F2
Cross e.g. 4 best sibs in the 2 best families (2 parents per grandparent)
Cross 4 best sibs
• Note that retrospectively SPM and multiple SPM (strategy 5) give identical pedigrees, thus identical increase of coancestry.
• Simple SPM (strategy 3) is a special case of multiple SPM (strategy 5) with 2 parents per family.
10
5
14
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25
Low budget
High budget
2
Medium budget
Families & parents cost nothing
Number of parents per selected family
An
nu
al p
rog
ress
(%
)
2=phenotypic
4
7
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20
Low budget (impossible)
Medium budget
High budget
2
Families & parents are expensive
Number of parents per selected family
Annual p
rogre
ss (%
)
Conclusions• Strategy 5 seems VERY promising and can beat phenotype strategy (strategy 3)
with 20-70 percent gain. Variants of strategy 5 which are still more efficient can be constructed.
• Strategy 5 can be implemented immediately. Select in field trials and graft in crossing archive. Make new selections when grafts mature for pollination, and harvest pollen from new selections.
• The actions are the same as for Strategy 3 (phenotypic selection), but more selections are done with strategy 5.
Recommendation (Dag): Start this immediately for the most suitable objects! I suggest setting the breeding population to 3 times the founders from now. When more studies, theoretical results and experiences (e.g. on male flowering in young trees) have accumulated, it may be increased. But that 3 times is better than no increase is safe enough to act on immediately. Even if it does not work, where are escapes to other strategies.
Note: The circumstances may make it motivated to use other strategies in specific cases, but this conclusion is safe enough to have it as main objective.
But Darius and Dag suggested Strategy 4 to be 20% better than phenotypic……. and this quantitative estimate seem uncertain… Can
the prediction on Strategy be trusted?• The estimate 20% was in “genetic merit” (take diversity loss at cycling in
consideration), including a heavy penalty for cycling. It also assumed a high cost for cycling. Thus and for other reasons the quantitative magnitude of the advantage may be debated, but strategy 4 still seems recommendable compared to Strategy 1, 2, and 3.
• Strategy 4 here assumes progeny-test following open pollination which may – or may not - be of some importance compared to the results by Darius and Dag.
• The current POPSIM which alternative comparisons are based on is based on genetic gain only, while Breeding cycler considers costs and time and gene diversity and optimizes things.
• The gain predicted is much higher! this variant of strategy 5 seems at least 20% better! But it may be 70%!
• The calculations are simpler! The conclusion is logic! (see next slide).• I make serious mistakes the whole time and there are detected mistakes in
Breeding-cycler, so it should not be taken for granted that breeding cycler predictions are right. However the frequent mistakes have till now not changed the main results.
• The scenario may be unrealistic, it may always happen.
Timing a la Curt 0804Strategy 3+2 4 3 1 2 5
Phen + Prog tandem
Phen preselection+
Prog
Phenotypic Progeny
Base
Progeny
IntensCombined
Phen and progeny
Cycling time, total
46 37 20 33 26 20
Sel age
Phenotype
13 15 13
15
Sel age
progeny
12 15 12 12
Use of cycle for testing
54% 81% 65% 36% 46% 75%
Förädlingsstrategier
1.
2.
3.
4.
5.
DPM
6.
7.
DPM
21-40 upprepasGen.tid: 38/ 2=19
Fältförsök
Korsning och frömognad
Växthus & friland
Mellanstock-arkiv
Arkiv
År
40x50=20000
10x50=500 50050
PC
250 (5x2x250)
40x50=20000PC
50050
200x50=10000 5x8 + 5x8 =40+40
13 (5x2x12.5)
100x50=5000 5 st/fam
5x50=250
40x250=10000
13 (5x2x12.5)
5x8 + 5x8=40+40
100x50=5000 6st/fam
38 (5x2x37.5) 100x300=30000
Sticklingprod.
14x40x50=28000
13 (5x2x12.5)
12x40x50=24000
2x40x50=4000
♀ 75+, ♂ 75+
10x50=500
Kottinsamling
5x8 + 5x8=40+40
DPM
DPM
DPMDPM
DPM
DPM
Mätning
50
50
50
50
50
150-300 13 (5x2x12.5)
1 st/fam
Picture constructed by Johan Westin and Curt Almqvist May 2008
Efficient use of breeding cycle
• The breeding cycle has two parts. Recombination and selection based on field test. Only selection based on field test generates gain. A most important component of a strategy is to use the breeding cycle with gain generating field testing.
• Progeny-testing utilizes the breeding cycle for field testing very inefficient. Phenotypic selection is better.
• But integrating phenotypic and progeny selection in a single cycle, as done in strategy 4 and 5, means that most of the breeding cycle is use for field testing and thus likely to be much more efficient.
• Making them in tandem is not as good use of the breeding cycle.