Forest Genetic Resources Training Guide
Tree seed supply chains
Genetic bottlenecks in the
restoration of Araucaria nemorosa
David Boshier &
Chris Kettle
Forest Genetic Resources Training Guide
Location of New Caledonia
Forest Genetic Resources Training Guide
What are the impacts of human
interventions on trees?
Forest Genetic Resources Training Guide
What are the impacts of human
interventions on trees?
Forest Genetic Resources Training Guide
A. rulei
endangered
A. muelleri
lower risk –
conservation
dependent
Forest Genetic Resources Training Guide
Araucaria nemorosa – critically endangered (IUCN)
monoecious flowers, self-compatible,
wind pollinated, wind dispersed
Forest Genetic Resources Training Guide
Forest Genetic Resources Training Guide
A. nemorosa
Forest Genetic Resources Training Guide
Forest Genetic Resources Training Guide
Forest Genetic Resources Training Guide
Study
Compared genetic
diversity in plants from
i. cones collected from
trees
vs
ii. seed from forest floor
Forest Genetic Resources Training Guide
Where & how should we
conserve?
Forest Genetic Resources Training Guide
Production of ripe cones in six natural
populations
Population
Code
Area
(ha)
N
Kaanua
N1
22.68
>1000
25
13
1
Vane
N2
15.72
>1000
15
8
New Forest
N3
15.2
>1000
63
Mini Nuri
Foret Nord
Natasha’s
N5
N6
N7
1.28
0.44
1.48
<500
36
28
62
93
<100
Sample # of
size
trees
>15cm
dbh
# of
trees
with
cones
# cones/
trees
with
cones
Mean
dbh (cm)
Minimum
dbh of trees
with cones
(cm)
2
14.9
16
1
7
25.6
48
45
4
1,2,3,3
18.2
18.5
22
11
23
4
5
2
2,2,7,5
1,1,1,3,9
2,8
18.4
17.1
12.9
22.5
32.7
23.5
Forest Genetic Resources Training Guide
How big is “big enough”?
• 50/500 rule (Franklin 1980)
• 50 - inbreeding depression to acceptable level
• 500 - sufficient for new variation from mutation to
replace that lost by genetic drift
• refers to effective population size (Ne) rather than
survey numbers (N) – so may need many more!
• in trees Ne smaller than N due to: overlapping
generations, dioecy, asynchronous flowering,
fecundity differences between individuals
Forest Genetic Resources Training Guide
Genetic diversity, % rare alleles (<0.1), inbreeding coefficients in:
adults (A), wild seedlings (W), nursery seedlings (N)
Population
Code
Sample
type
Kaanua
N1
A
Kaanua
N1
Kaanua
AE (S.E.)
He (S.E.)
% rare
alleles
FIS
Ne
9.53
(2.46)
0.72 (0.09)
84
0.135*
W
8.83
(1.90)
0.71 (0.09)
74
0.194*
30
N1
N
2.81
(0.46)
0.46 (0.09)
38
-0.024n.s.
1
Foret Nord
N6
A
6.12 (1.11) 0.65 (0.07)
68
0.009n.s.
Foret Nord
N6
W
5.59
(0.90)
0.62 (0.07)
65
0.168*
11
Foret Nord
N6
N
6.40
(0.87)
0.69 (0.05)
65
0.282*
N/C
Forest Genetic Resources Training Guide
Theory
• direct impacts
genetic processes
• decrease pop. size
genetic drift
• increase spatial isolation
gene flow
• decrease densities
mating - inbreeding
• change local environment
selection
Forest Genetic Resources Training Guide
Bottleneck  genetic drift
Forest Genetic Resources Training Guide
Your mission
• draw out the seed supply chain
• design a strategy for the collection
and use of germplasm
Objective – ensure the maintenance of genetic
diversity in the on-going restoration efforts for
this threatened species
Forest Genetic Resources Training Guide
How?
• Step 1 - map out the seed/germplasm
supply chain for A. nemorosa
• Draw a flow diagram of the chain, from the source to
the final user, within the field of restoration (from
seed tree  to a new plant in its final use).
• The map should identify
• players (individuals, institutions) and processes in the chain
(what the players do)
• influences of the chain on genetic variation (bottlenecks,
selection, genetic drift)
• limiting social factors in the chain (e.g. policies/laws, business,
institutions or resources)
Forest Genetic Resources Training Guide
Forest Genetic Resources Training Guide
How?
• Step 2 – analysis
• What are the genetic risks associated with the actual
system of seeds?
• Specific recommendations to improve the situation,
dealing with the diversity within the seed system (e.g.
practical methods of collecting germplasm that ensure
genetic diversity in restoration efforts)
Forest Genetic Resources Training Guide