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Sweet genes:
Do we shape the gene pool of our forests ?
Thomas Geburek
Department of Forest Genetics
Trees are extremely long-lived individuals on our globe!
bristlecone pine (Pinus aristata)
up to 4600 years
... and have often a huge natural distribution area !
Scots pine (Pinus sylvestris)
Nystedt et al. 2013 (Nature, 497, 579-584)
28,354 genes identified in Picea abies
„maternal“ chromosome
allele
„paternal“ chromosome
allele
homozygous gene(locus)
„maternal“ chromosome
allele
„paternal“ chromosome
allele
heterozygous gene(locus)
Diversifying Factors
Selection
Homogeneizing Factor
Gene
Pool
Gene Flow
Six times elevated mutation rate in wheat exposed for one
year to Chernobly radiation.
Selection
Selection
Response to selection (selective gain)
= intensity of selection x heritability (narrow sense)
R = s x h2
Gene Flow
Gene Flow
Blowing in the wind .....
Gene flow
Genetic Drift
lime 24
raspberry 60
orange 1
cherry 10
pineapple 5
Gene pool 100 „sweet genes“
1. Step
random mating
2. Step
allelic richness and heterozygosity
3. Step
run population through a bottleneck
(pick blindly 6 individuals)
4. Step
allelic richness and heterozygosity
Genetic Drift
Heterozygosity after the bottleneck of size N
Hafter= [1- 1/(2N)] Hbefore
H [%] 75
NIND
2
91.7
95
97.5
99
99.5
6
10
20
50
100
allelic richness
after the bottleneck
probability of
loosing alleles
N
p1 = 0.60
p2 = 0.24
p3 = 0.10
p4 = 0.05
p5= 0.01
1
1.00
2
2.21
6
3.26
10
3.70
50
4.62
unlimited
5.00
E = m - (1-p)2N
allelic richness
before the bottleneck
Hampe & Petit (2005) Ecological Letters
How do we affect the gene pool of forest trees?
Identify major points and discuss the issue together with
your group members, prepare a 5-minute summary!
Thomas Geburek
Department of Forest Genetics
[email protected]