Download Genetic population structure in northern shrimp (Pandalus borealis

Genetic population structure
in northern shrimp (Pandalus borealis)
in the North Atlantic
Guldborg Søvik, Torild Johansen, Jon-Ivar Westgaard, Anne Dagrun Sandvik,
Michael Kingsley, Carsten Hvingel, Halvor Knutsen, Knut Jørstad
Havforskningsinstituttet
Per Erik Jorde
Universitetet i Oslo
Carl Andre, Ricardo Pereyra
Göteborg Universitet
1
1
Background
ICES shrimp working
group wanted
knowledge about the
stock structure of
shrimp in the North Sea
and Skagerrak
Three stocks previosly
defined based on spatial
separation and life history
parameters:
• Fladen Ground
• Farn Deep
• Norwegian Deep/Skagerrak
2
2
Project: POPBOREALIS
• Investigations extended to the whole North Atlantic.
• Two projects:
Investigations of population structure
in shrimp (Pandalus borealis) in the North Atlantic
(Norwegian Research Council)
Sustainable shrimp fishery in Skagerrak
(Interreg IVA)
3
Photo: Ø. Paulsen
3
Goals
• 1) Test the population structure of shrimp on a spatial and
temporal scale within and between the presently defined
management units in the North Sea.
– larval drift, migration patterns (source-sink dynamics)
– inshore ↔ offshore areas in Skagerrak.
• 2) Place the North Sea shrimp in a broader context by
comparing with estimated shrimp stock structure in the
whole North Atlantic.
Photo: Ø. Paulsen
4
4
Stock structure
A
B
C
Panmixia
Isolation
Fig: H. Knutsen
D
Divergence
Genetic differences and demographic independence can
be demonstrated with modern DNA-technology and used
as a tool to identify stock structure
5
5
Distribution of shrimp
6
6
Samples
Shrimp samples from colleagues
in the ICES shrimp working group
and local fishermen
7
7
POPBOREALIS
GOM = Gulf of Main; GRB = Grand Banks; FLC = Flemish Cap;
LAB = Labrador; HUS = Hudson Strait; WGS/WGN = West Greenland
South/North; ICE = Iceland; NDS/NDN = Norwegian Deep South/North; NOM =
Norway Mid; BSS/BSC = Barents Sea South/Central; SPW = Spitsbergen West
8
8
Fst-values –
measure of genetic difference
=> estimate the proportion of genetic variation
that can be explained by differences between populations.
Example: Fst = 0.05
=> 5% of the total genetic variation come from
between pop. differences.
=> 95 % come from within pop. differences.
This illustrates the large variation within populations.
9
9
MDS-plott
10
10
Isolation by distance
11
11
What other factors (apart from distance) can explain
the observed differentiation pattern?
Dispersive processes:
Random genetic drift
Natural selection in heterogeneous environment
Mutations (non-recurring)
Converging processes:
Migration (=gene flow)
Natural selection in a common environment
Recurrent mutations
12
12
Genetic drift + migration
Results of computer simulations of random genetic
drift and gene flow among hypothetical isolated and
interconnected populations:
Interconnected (by gene flow)
populations converge genetically
Isolated populations appear at
random in the MDS plot
13
13
14
14
Can genetic drift and migration (=gene flow)
explain the observed differentiation pattern?
Connected?
Connected?
Connected?
Isolated?
15
15
Pelagic larvae
 Drift with ocean currents
 Spread genes
16
16
Genetic drift + migration
Can ocean currects explain differences/similarities?
17
17
66
Canada
SFA 2
Combined
64
Greenland
Groenland
62
SFA 3
Today: several management units
200 m
60
800 m
SFA 4
Genetics:
One stock along eastern Canada?
One stock on Flemish cap?
200 Nmi Limit
Closed areas
58
56
SFA 5
54
Labrador
52
Quebec
SFA 6
50
SFA 8
SFA 10
SFA 12
Newfoundland
Terre-Neuve
SFA 9
48
46
New Brunswick
Nouveau-Brunswick
P.E.I/I.P.E
SFA 13
Nova Scotia
Nouveau-Ecosse
44
42
-70
SFA 7
SFA 15
SFA 14
SFA 16
www.dfo-mpo.gc.ca
-65
-60
-55
-50
18
-45
18
Barents Sea
Today: one stock, genetics show the same
19
19
Norwegian Deep and Gulf of Maine
Natural selection in a common environment?
20
20
Takk for
oppmerksomheten
21
21