Genetic variation and Genetic variation and geographic structure of coastal geographic structure of coastal cutthroat trout at the northern cutthroat trout at the northern

extent of their range, extent of their range, Prince William Sound, AlaskaPrince William Sound, Alaska

Kitty E. GriswoldKitty E. GriswoldUSGS/BRD Conte Anadromous Fisheries Research CenterUSGS/BRD Conte Anadromous Fisheries Research Center

Turners Falls, MATurners Falls, MAUniversity of Massachusetts, AmherstUniversity of Massachusetts, Amherst

Kenneth P. CurrensKenneth P. CurrensNWIFC, Olympia WANWIFC, Olympia WA

Gordon H. ReevesGordon H. ReevesPNW Research Station, Corvallis, ORPNW Research Station, Corvallis, OR

Genetic structure at the local scaleGenetic structure at the local scale

Why use genetic tools?Why use genetic tools?

Patterns tell us Patterns tell us about species about species historyhistory

Relative degree of Relative degree of isolation/gene flowisolation/gene flow

Over space and Over space and time landscapes time landscapes are dynamicare dynamic

Distributional range of Distributional range of coastal cutthroat troutcoastal cutthroat trout

Gulf of Alaska

Northern extent of range Northern extent of range (8,000 ybp)(8,000 ybp)

Gulf of Alaska

Prince William Sound

150 years350 years

Two sites above presumed waterfall barriers

Goals for this talkGoals for this talk

Genetic variation in Prince William Sound, Genetic variation in Prince William Sound, AK with two genetic toolsAK with two genetic tools

Correlation of genetic and geographic Correlation of genetic and geographic distance in coastal cutthroat trout in distance in coastal cutthroat trout in Prince William Sound, AKPrince William Sound, AK

Otolith microchemistry analysisOtolith microchemistry analysis

Types of genetic variation and Types of genetic variation and their applicationstheir applications

Mitochondrial DNAMitochondrial DNA• maternally inherited• doesn’t undergo recombination

AllozymesAllozymes

Microsatellite DNAMicrosatellite DNA• hypervariable • tandem repeats (AGAGAGAG)

Ancestral LineagesAncestral Lineages

KinshipKinship

Data AnalysisData Analysis

Haplotype diversity within Prince William Haplotype diversity within Prince William SoundSound

Genetic variation within sampling locationsGenetic variation within sampling locationsAlleles per locusAlleles per locusHeterozygosityHeterozygosity

Genetic variation among sampling Genetic variation among sampling locationslocations

Genetic distanceGenetic distanceTest models of genetic structureTest models of genetic structure

Isolation by distance (IBD)Isolation by distance (IBD)

Dispersal of organisms has limit which Dispersal of organisms has limit which leads to a geographic patternleads to a geographic pattern

Isolation by distance Isolation by distance genetic differentiation increases with distancegenetic differentiation increases with distance

Migrants/generation (M) geographic Migrants/generation (M) geographic distance (d) distance (d)

Mantel test for significanceMantel test for significanceRegression Regression

Slope of line describes model fitSlope of line describes model fit

One dimensional stepping stone One dimensional stepping stone modelmodel

Slatkin (1993)

One dimensional stepping stone One dimensional stepping stone modelmodel

Slatkin (1993)

Log(distance)

Log(M)

Slope=-1.0

MtDNA MtDNA ResultsResults

ND-1 ND 5-6D-Loop(N=79)

16 RFLP’s

Within sample genetic variation Within sample genetic variation Alleles/LocusAlleles/Locus

0

2

4

6

8

1 0

1 2

Col

umbi

a B

ay

Una

kwik

Inle

t

Gun

boat

Lak

es

Wes

t Arm

Stu

mp

Lake

Gre

en Is

land

She

lter C

r (be

low

)

She

lter C

r (ab

ove)

Mak

aka

Cr

Haw

kins

Cr (

belo

w)

Haw

kins

Cr (

abov

e)

Milt

on L

ake

Cop

per R

iver

Sampling location

Alleles/Locus

Within sample genetic variation Within sample genetic variation average heterozygosityaverage heterozygosity

0 . 0 0

0 . 1 0

0 . 2 0

0 . 3 0

0 . 4 0

0 . 5 0

0 . 6 0

0 . 7 0

0 . 8 0

0 . 9 0

1 . 0 0

Col

umbi

a B

ay

Una

kwik

Inle

t

Gun

boat

Lak

es

Wes

t Arm

Stu

mp

Lake

Gre

en Is

land

She

lter C

r (be

low

)

She

lter C

r (ab

ove)

Mak

aka

Cr

Haw

kins

Cr (

belo

w)

Haw

kins

Cr (

abov

e)

Milt

on L

ake

Cop

per R

iver

Sampling location

He

12

3

4

5

6

78

910

11

12

13

00.

050.

100.

150.

200.

25

CordovaOrca Bay

Models of IBDModels of IBD

PostPost--glacial colonization route glacial colonization route

Shoreline migration route (5Shoreline migration route (5--10 km)10 km)

Shortest distance between sites Shortest distance between sites (open water)(open water)

Results IBD Mantel testsResults IBD Mantel tests

PostPost--glacial colonization route glacial colonization route (p<0.009)(p<0.009)

Shoreline migration route (5Shoreline migration route (5--10 km 10 km open water) (p=0.015)open water) (p=0.015)

Shortest distance between sites Shortest distance between sites (open water) (p>0.05)(open water) (p>0.05)

IBD slopeIBD slope

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0

log(kM)

log(

M)

Shelter Bay (above x below)

Hawkins Cr (above x below)

Columbia Bay x Unakwik Ilet Columbia Bay

x Green Is

Columbia Bay x Gunboat Lk

Slope= -0.836

ConclusionsConclusionsGeographic pattern of genetic variationGeographic pattern of genetic variation

Northwest PWS sites significantly lower numbers of Northwest PWS sites significantly lower numbers of alleles and average heterozygosityalleles and average heterozygosity

Genetic distance appeared to be Genetic distance appeared to be correlated to geographic distancecorrelated to geographic distance

Support for IBDSupport for IBDEast west dispersal following shorelinesEast west dispersal following shorelines

Above barrier sites unresolvedAbove barrier sites unresolved

12

3

4

5

6

78

910

11

12

13

00.

050.

100.

150.

200.

25

CordovaOrca Bay

Otolith MicrochemistryOtolith Microchemistry

Use elevated levels of Sr/Ca ratios in Use elevated levels of Sr/Ca ratios in otoliths to infer entry to seawaterotoliths to infer entry to seawater

Otolith microchemistryOtolith microchemistry

Coastal cutthroat trout, Shelter Bay, AK

0

0.001

0.002

0.003

0.004

primordia edge

1+2+

3+

4+5+

6+

Sr/Caratio

Primordia to edge

Shelter Bay Anadromous cutthroat trout

0

0.001

0.002

0.003

0.004

1 3 5 7 9 11 13 15 17 19

primordia to edge

Sr/C

a ra

tio

3+ trout

Otolith microchemistryOtolith microchemistry

Primordia values of above and Primordia values of above and below barrier coastal cutthroat below barrier coastal cutthroat

trouttrout

Shelter Bay, Alaska Anadromous cutthroat trout

0

0.001

0.002

0.003

0.004

1 3 5 7 9 11 13 15 17 19

primordia to edge

Sr/C

a ra

tio

3+ trout

Shelter Lake, Alaska cutthroat trout

0

0.001

0.002

0.003

0.004

0.005

1 3 5 7 9 11 13 15 17 19

primordia to edgeSr

/Ca

ratio

3+ trout

Primordia samples of above and below populationsnot significantly different (p > 0.05)

Size at ageSize at age

Size at age coastal cutthroat trout

01234567

0 100 200 300 400

length in mm

age

Shelter BayAnadromousShelter Lake

Bottom lineBottom line

Genetic tools useful for describing Genetic tools useful for describing geographic variation in coastal geographic variation in coastal cutthroat troutcutthroat trout

Scale the tool to the questionScale the tool to the question

Genetic tools used in combination Genetic tools used in combination with ecological measures with ecological measures

Sites in northern PWS have reduced genetic diversity

Populations of coastal cutthroat trout in PWS range from being similar to different with IBD patterns

AcknowledgementsAcknowledgements

Oregon State UniversityOregon State UniversityOregon Cooperative Fisheries Research UnitOregon Cooperative Fisheries Research UnitChugach National Forest, CordovaChugach National Forest, CordovaExxon Valdez Trustee CouncilExxon Valdez Trustee CouncilAlaska Department of Fish and GameAlaska Department of Fish and GameIndividuals Janet Hanus, Dave Schmid, Merlyn Individuals Janet Hanus, Dave Schmid, Merlyn Schelske, Dave Saiget, George Covell, Kathryn Schelske, Dave Saiget, George Covell, Kathryn Ronenberg.Ronenberg.Coastal cutthroat trout symposium travel grantCoastal cutthroat trout symposium travel grant

0.2

0.4

0.6

0.8

I

II

III

IV

V

VI

VII

Copper Ri ver

Milton Lake

Hawkins Creek(above barrier)

Hawkins Creek(below barrier)

Makaka Creek

Shelter Bay(above barrier)

Shelter Bay(below barrier)

Green Island

Stump Lake

West Arm,Bay of Isles

Gunboat Lakes

Unakwi kInlet

Columbi a Bay

Bayesian Structure of PopulationsBayesian Structure of Populations

(Pritchard et al. 2000)