1

Continued Progress in Desert Tortoise Conservation using Molecular Biology

Taylor EdwardsGenomic Analysis and Technology Core

University of Arizona

The Genographic Project

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Conservation Genetics

• Conservation Biologists strive to provide principles and tools for preserving biodiversity

• Biodiversity: The structural and functional variety of life forms at genetic, population, community, and ecosystem levels. (Sandlundet al. 1992)

DNA Fingerprinting

(GAT)15+ “microsatellite”

The Desert Tortoise Genomics Project

I. Defining the Desert Tortoise

a. Gene flow – ESU’sb. Maternal genealogy

II. PaternityIII. Behavioral GeneticsIV. Hybridization ZonesV. Mexican Tortoise Project

Photo: Curtis Bjurlin

The Desert Tortoise Genomics Project

I. Defining the Desert Tortoise

a. Gene flow – ESU’sb. Maternal genealogy

II. PaternityIII. Behavioral GeneticsIV. Hybridization ZonesV. Mexican Tortoise Project

3

Molecular Support for the Established Recovery Units in the

Mojave Population of Desert Tortoises (Gopherus agassizii)

Taylor Edwards, Robert Murphy, Kristin H. Berry and Ann McLuckie

Arizona

G. agassiziiHabitat

Preferences

Mojave Population

Evolutionarily Significant Units (ESUs)

Recovery units for the desert tortoise were identified based on ESUs using data on genetic variability, morphology, behavior patterns, and habitat associations.

1

CA

AZ

MX

NV UT

Western Mojave

Eastern Mojave

Northeastern Mojave

Northern Colorado

Eastern Colorado

Upper Virgin River

Col

orad

o R

iver

sample groups

recovery unitboundaries (USFWS 1994)

1 32

7

14

10

5

15

68

9

11

12

13

4

Las Vegas

St. George

Los Angeles

N 0 100 km

Locations of 15 Sampled Groups

Sampled Desert RegionsDesert Region / Recovery Unit

Sample Group

# of Samples in Group

Western Mojave 1 622 83

Central Mojave 3 194 315 47

Southern Mojave 6 267 718 749 2710 19

Northeastern Mojave 11 60Eastern Mojave 12 31Northern Colorado 13 18Eastern Colorado 14 37Upper Virgin River 15 23

628

Methods628 Tortoises

• Distribution – Sampled from all DWMAs (ex. Joshua Tree)– Representing all Recovery Units– Represent over a decade of research efforts

• DNA Fingerprinting; 15 Microsatellite markers (11 variable)

• mtDNA sequencing for 131 individuals

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Microsatellite descriptive statistics

93.93% 6.07%

Within GroupsAmong Groups

Percentage of Variation

FST = 0.061 (p<0.001)

Study sites are genetically similar:Suggests that gene flow occurs/occurred

MDS Analysis of Genetic Distance (Fst) for 15 Mojave desert tortoise groups(Stress = 1.39)

I-0.80 -0.05 0.70 1.45 2.20

II

-1.10

-0.45

0.20

0.85

1.50

1

2 3

4

5

6

7

8

9

10

11

12

13

14

15

MDS Analysis of Genetic Distance (Fst) for 15 Mojave desert tortoise groups(Stress = 1.39)

I-0.80 -0.05 0.70 1.45 2.20

II

-1.10

-0.45

0.20

0.85

1.50

1

2 3

4

5

6

7

8

9

10

11

12

13

14

15

E

N

Southern Mojave

Central Mojave

Western Mojave

Northern Colorado

Northeastern Mojave

Eastern Colorado

Eastern Mojave

Upper Virgin River

Comparison of genetic distance to geographic distance:

Mantel Test; r2 = .646

The correlation accounts for approximately 65% of the variation observed

Isolation by Distance

The desert tortoise is perhaps the ideal organism for the IBD model; one that is distributed across the landscape in patches and for which the difficulty of dispersal is a function of geography.

- Edwards et al. (2004)

Assignment test

95.72223Upper Virgin River89.23337Eastern Colorado72.21318Northern Colorado54.81731Eastern Mojave81.74960Northeastern Mojave59.6118198Southern Mojave68.06697Central Mojave84.8139164Western Mojave

% correctly assigned

# correctly assigned

# of SamplesSample Group

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Maternal Lineage (mtDNA) Tree

Broadly distributedMojave Haplogroup

Northeastern Mojave Haplogroup

Sonoran Haplogroup

(~5 mya divergence from Mojave)

1

CA

AZ

MX

NV UT

Col

orad

o R

iver

sample groups

recovery unitboundaries (USFWS 1994)

Las Vegas

St. George

Los Angeles

N 0 100 km

MtDNA Haplotype

Distribution

1

1

11

11 1

1 1

1

11

Haplogroup A2 2

3

3

4

5

10

98

7

9

Haplogroup B

6

6

6

6

1

1

CA

AZ

MX

NV UT

Western Mojave

Eastern Mojave

Northeastern Mojave

Northern Colorado

Eastern Colorado

Upper Virgin River

Col

orad

o R

iver

sample groups

recovery unitboundaries (USFWS 1994)

1 32

7

14

10

5

15

68

9

11

12

13

4

Las Vegas

St. George

Los Angeles

N 0 100 km

Revised Recovery Units suggested for the Mojave Population of the Desert Tortoise

1

CA

AZ

MX

NVUT

WesternMojave

Northeastern Mojave

Northern Colorado

Eastern Colorado

Upper Virgin River

Col

orad

o R

iver

sample groups

potential recovery unit boundaries 1 3

2

7

14

10

5

15

68

9

11

12

13

4

Las Vegas

St. George

Los Angeles

Central Mojave

SouthernMojave

0 100 km

N

Revised Recovery Units suggested for the Mojave Population of the Desert Tortoise Eastern

Mojave

?

Structure 2.1 - Bayesian clustering method used to assess support for splitting the current “Western Mojave Recovery

Unit” into 3 separate units for management

• RED = Western RU• GREEN = Central RU• BLUE = Southern RU

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St. GeorgeSt. George

Locations of captive and translocated tortoises

Colorado Desert

?

Los AngelesLos Angeles

NeedlesNeedles

Las VegasLas Vegas

BarstowBarstow

NVUT

CA

AZ

MX

Mojave Desert

0 100 kmN

?

?

1997-2004

~1940-1983

Represents >1,000 documented releases!

The genetic affects of translocatedtortoises are observed in our data

Summary

• The 1994 Recovery Plan adequately designates Recovery Units for the Mojave population of the Desert Tortoise

• Our data suggest that the current “Western Recovery Unit” can be differentiated into 3 separate units; Western, Central, and Southern

Summary

• The Eastern Mojave and Northern Colorado Recovery Units warrant greater investigation

• The Northeastern and Upper Virgin River Recovery Units show the strongest differentiation and may in fact be more genetically isolated

Summary

• The integration of translocated tortoises could potentially compromise the genetic integrity of a desert tortoise management unit

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Tracing the Movements of SonoranDesert Tortoises with Molecular Biology

?

Outcome #1Populations genetically distinct,

(gene flow does NOT occur)

Management Implications:Loss of genetic diversity

X

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Outcome #2Populations genetically similar, (gene

flow occurs)

Management Implications:Historical gene flow is currently

hindered by human development

\\

//

//

//\\

\\

\\

\\

Gen

etic

Dis

tanc

e (F

st)

Geographic Distance (km)(Mantel test; r = 0.554, p = 0.030)

Isolation by Distance

Absolute number of migrants exchanged per generation

between populationsMethod:• Slatkin’s M = 2.9 (minimum)• Private allele method = 5.5

Gene flow occurred historically at a rate greater than one migrant per generation

Interstate 10

Saguaro NP

Rail line

Santa Rita Mtns.

Rincon Mtns.

10 km

Tucson

Thelma's mad dashA radio-tagged desert tortoise takes off on a wild trek that leaves her trackers stunned.

Tucson Citizen, May 12, 2003Thelma didn't exactly run away from home. For one thing, she's hardly a child - one estimate puts her age at about 30. For another, her pace was far from sizzling. After all, desert tortoises aren't known for their speed. But what she lacked in tempo, she made up for in determination. Thelma - her name was inspired by the wanderings of the famous movie duo Thelma and Louise - left Saguaro National Park's east unit in the fall of 2000, not long after being outfitted with a radio transmitter to track her movements….

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Phoenix

Tucson

= Tortoise Population

I-8

I-10

I-17

I-19

I-10 Phoenix

Tucson

= Tortoise Population

= Interstate

= Tortoise Population

Phoenix

Tucson

I-17

I-10

I-8

I-10

I-19

= Road= Interstate

= Tortoise Population

Phoenix

Tucson

= Urban buffer

Discussion

• Gene flow occurs (or historically occurred) among mountain “island” populations

• Connectivity between seemingly isolated populations is likely important to long-term population viability

• Populations that are currently isolated may require management options like translocations for long-term maintenance

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Many people have contributed

• field biologists• research

scientists• multi-

disciplinary teams

Acknowledgements• K.Berry• R. Murphy• D.J. Morafka• A. McLuckie• M. Kaplan • H-W. Herrmann• A. Lathrop• A. Ngo• R. MacCulloch• A. Demmon

• K. Anderson• R.J. Turner • T. Bailey• R. Evans• R. Woodard• P. Woodman• P. Frank• B.L. Burge• B. Henen• K. Nagy

• Cristina Jones• Bruce Weise• Josh Capps• Daren Riedle• Steve Goodman• Jeff Pebworth• Teal Richards• Cecil Schwalbe• Peter Woodman

• Arizona Game and Fish Department• University of Arizona• Saguaro National Park• U.S. Geological Survey• Southwestern Parks and Monuments Assoc.• Genomic Analysis and Technology Core• SW Cooperative Ecosystem Study Unit• U.S. Fish and Wildlife Service• California Fish & Game• Bureau of Land Management• Utah Division of Wildlife Resources

Cooperating Agencies: Funding• U.S. Army NTC Ft. Irwin• U.S. Air Force – Edwards Air Force Base• USGS• Royal Ontario Museum Foundation• Arizona Game and Fish Department• NSERC• CSUDH Foundation• Marine Corps – MCAGCC• Arizona Research Laboratories

Thank you!

CONSERVATION BIOLOGY IN NAMIBIASUMMER SESSION I:

MAY 14 - JUNE 24 2007

• Open to Undergraduate, Graduate and Non-degree Students• Take on a five week expedition into Namibia’s extraordinary Namib Desert• Experience real field research in Africa• Earn direct University of Arizona credit

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CONSERVATION BIOLOGY IN VIETNAMSUMMER SESSION II:

JULY 6 - AUGUST 16, 2007

• Open to Undergraduate, Graduate and Non-Degree Students

• Take expeditions to various biodiversity hotspots in Northern and Central Vietnam

• Experience real field research and participate first hand in

conservation efforts in tropical forests

www.studyabroad.arizona.eduAPPLICATIONS AVAILABLE AT

The Office of Study Abroad & Student Exchange (520) 626-9211

FOR MORE INFORMATION, CONTACTDr. Hans-Werner Herrmann, hwh@u.arizona.edu

or Taylor Edwards, taylore@u.arizona.edu

Register for: RNR 495A/595A (6 units)Field Studies in Developing Countries