greg albrecht dr. sarah m. hardy dr. kris hundertmark
TRANSCRIPT
Defining genetic population structure of snow crab
(Chionoecetes opilio) in the Bering, Chukchi and Beaufort
Seas Greg Albrecht
Dr. Sarah M. HardyDr. Kris Hundertmark
Outline•Species information•Study area•Factors influencing current populations•Purpose of study•Methods •Progress
Distribution(Approximated)
Koryaks.net
Life HistoryPlanktonic zoea – (hatch in
winter – spring, 2 stages, 3-5 months)
Settle as megalopaeMolt through 7-9 instars
Males: 5-10 yearsFemales: 3-7 years
Terminal molt to maturityUp to 7 years post terminal
moltMales: 11-17 yearsFemales: 10-13 years
uwlax.edu
Kruse et al. 2007
Shell condition Index (Not full representation)
1 2
3 4
•Abdominal flap is proportionally larger in mature females
MatingMating in late winterFemales can store sperm in spermathaeca for
later useMales can fertilize several femalesYoung are brooded 12-15 months then
released into water column
Female
Male
Larval Dispersal
Predominantly northward flow
Bering Strait to Pt. Barrow ~6 months
Weingartner et al. 2005
Bering SeaLocal
recruitmentEddiesWeak
currents in central
Southward migration?
Stabeno 2001
Mean circulation of upper 40 m
MigrationAdult females
move from coastal domain towards outer domain (SW)
Male migration not studied as well
Koryaks.net
Ernst et al. 2005
The forces at workCommercial fishing
pressureConcentrating on southern
extent of populationClimate change
Temperatures, ice extent, ocean currents, wind & mixing
Predator preyPacific Cod (Gadus
macrocephalus) and other bottom fish
Resource exploration
Commercial HarvestOne of the largest
crab fisheries in the world2008~ 90 million
dollars1992~ 192 million
Replaced dwindling Tanner (C. bairdi) stocks in 1980s
rcrawford79.wordpress.com
Kruse et al. 2007
Climate changeIce extent determines
cold pool (<2 C)Cold pool trapped by
stratified warm waterCrabs follow cold poolCan crabs re-colonize
south after a warm year?
Cod predation may be too intenseOrensanz et al .
2004
Resource Exploration Areas
Alaska Annual Studies Plan. U.S. Dept. of Interior 2009
Purpose of StudyGain a better understanding of genetic
connectivity Identify genetically distinct subpopulations if
they existGain a better understanding of larval
dispersal distances
Sampling
Sampled
Commercial fishing
Planned sampling
Resource development
MethodsBased on Puebla et al. 2008 (North Atlantic)Extract DNA samples from tissue in ~ 1000
adult female C. opilio samples collected from throughout their range
Amplify DNA using PCR at 8 microsatellite locations
Genotype each individualUse statistical programs to analyze results
and look for distinct populationsMatch larval crabs with upstream
populations
Why Microsatellites?Definition: Molecular markers consisting of
repeat nucleotide units at various locations within nuclear DNA
Previously established for this species by Puebla et al. 2003
Shown to be informative in this speciesHighly polymorphic, yet not under selection
pressuresDeviation from Hardy-Weinberg equilibrium
can be used to detect isolation of a group of individuals
StatisticsA suite of computer programs will be used to
identify genetically isolated populationsF-statistics
Compare pre-established groups in a framework similar to ANOVA
Bayesian methods Assemble populations based on similarity of genetic
signatures
The big picture
8 primers (Identify region for copying)
Taq polymerase(Copies DNA)
Crab DNAPCR(Copying of target DNA) Electrophoresis
Scoring of each individual’s electropherogram
Statistical analysis of genetic signatures
Microsatellite locations are represented by different colors
So how does this work?
100 110
100
110
PCR
Allele “A”
Allele “B”
Heterozygote
Primer region
Population “A”
Population “B”
Electropherogram
Mating
Electrophoresis
100 100
100
100
PCR
Allele “A”
Allele “A”
Homozygote
Primer region
Population “A”
Population “A”
Electropherogram
PCR conditions must be optimized for good amplification
Mating
Electrophoresis
Chukchi
Chukchi
Chukchi
Beaufort
Progress to dateExtracted ~150 samplesTested DNA quality and found donated
Bering samples to be lowMultiplexed all 8 primersTrial and error of PCR conditions (various
annealing temperatures and times, Taq polymerases)
Initial genotyping of individuals
TimelineWinter 2009/10 – begin genotyping (currently
underway)May 2010 – have completed genotyping and
preliminary statistical analysis for 60 individuals
July 2010 – Collect samples from Bering Sea on F&G trawl survey cruise
February 2011 – have completed genotyping and analysis for entire sample collection
September 2011 – have written and defended thesis
Literature Cited• Ernst, B., Orensanz J. M. & Armstrong, D. A. 2005. Spatial dynamics of female snow crab
(Chionoecetes opilio) in the eastern Bering Sea. Canadian Journal of Fisheries and Aquatic Science 62:250-268.
• Kruse, G.H. , Tyler, A.V, Sainte-Marie, B., Pengilly, D. 2007. A workshop on mechanisms affecting year-class strength formation in snow crabs Chionoecetes opilio in the Eastern Bering Sea
• Orensanz, J., B. Ernst, D. A. Armstrong, P. Stabeno, and P. Livingston. 2004. Contraction of the geographic range of distribution of snow crab (Chionoecetes opilio) in the Eastern Bering Sea: An environmental ratchet? Pages 65-79, CalCOFI Report.
• Puebla, O., Parent, E. & Sevigny, J.-M. 2003. New microsatellite markers for the snow crab Chionoecetes opilio (Brachyura: Majidae). Molecular Ecology Notes. 3:644-646.
• Puebla, O., Sevigny, J.-M., Sainte-Marie, B., Brethes, J.-C., Burmeister, A., Dawe, E. G. and Moriyasu. M. 2008. Population genetic structure of the snow crab (Chionoecetes opilio) at the Northwest Atlantic scale. Canadian Journal of Fisheries and Aquatic Sciences 65:425-436.
• Stabeno, P.J., Kachel, N.B., Salo, S.A. & Schumacher, J.D. 2001. On the temporal variability of the physical environment over the south-eastern Bering Sea. Fisheries Oceanography
10(1) 81-98.• Weingartner, T., Aagaard, K., Woodgate, R., Danielson, S., Yasunori, S. & Cavalieri, D. 2005.
Circulation on the north central Chukchi Sea shelf. Deep-Sea Research II 52: 3150-3174.
Questions and Comments?