This study analyzed genetic data from bluelined surgeonfish (Acanthurus nigroris) collected across the Hawaiian archipelago and wider Pacific to investigate population connectivity. There was no genetic structure found within Hawaii or across the wider Pacific, indicating high gene flow over large distances. However, a distinct genetic barrier was detected between Hawaii and other Pacific populations, suggesting two separate species. This has implications for defining management units and marine reserves for this species in the region.

1. Cryptic surgeonfish species:
Phylogeographic survey reveals hidden
biodiversity in the Pacific Ocean
J. DiBattista, C. Wilcox, M. Craig, L. Rocha, and B. Bowen
Hawai’i Institute of Marine Biology, University of Hawaii

2. Genetic connectivity of reef fish
Most have high dispersal potential:
- pelagic larvae (weeks to months)

3. Genetic connectivity of reef fish
Most have high dispersal potential:
- pelagic larvae (weeks to months)
Direct tagging logistically difficult:
 Molecular tools important here

4. Genetic connectivity of reef fish
Most have high dispersal potential:
- pelagic larvae (weeks to months)
Direct tagging logistically difficult:
 Molecular tools important here
Scale of dispersal fundamental for:
- defining management units
- designing marine reserves (MPAs)
- Identifying sources versus sinks

5. Phylogeography of Indo-Pacific reef fish
OK
HI
JO
MA
PN KI
KA TI
SE DG
AS MO
CM MA
FJ
Reef fish families CC
Acanthuridae
Chaetodontidae
Labridae
Lutjanidae
Mullidae
Pomacanthidae
Serranidae

6. Phylogeography of Indo-Pacific reef fish
OK
HI
Hawaiian archipelago
JO
MA
PN KI
KA TI
SE DG
AS MO
CM MA
FJ
Reef fish families CC
Acanthuridae
Chaetodontidae
Labridae
Lutjanidae
Mullidae
Pomacanthidae
Serranidae

7. Hawaiian archipelago
25% endemism (Randall 2007)
One of the most isolated in the Pacific

8. Papahā naumokuā kea
Marine National Monument
?
?
One of the largest marine conservation areas in the world

9. Bluelined Surgeonfish
(Acanthurus nigroris)
• Reef generalist/herbivore
• 542 specimens collected
 2004 to 2007
• 18 locations sampled
 Hawaii and Pacific islands
• mtDNA, cytochrome b

10. Pacific locations
Hawaiian Locations
N = 98
Marshall Islands
(N = 19, MI)
Christmas Island
Kiribati
(N = 24, KI)
American Samoa
(N = 23, AS)
Moorea
(N = 32, MO)
Photo by Jerker Tamelander, IUCN

11. Hawaiian locations
N = 445
Midway (N = 30)
Pearl & Hermes (N = 29)
Kure (N = 41)
Lisianski
(N = 39) Gardner Main Hawaiian Islands (MHI)
Laysan (N = 27)
(N = 46) N = 96
Maro Reef Necker Island
(N = 35) (N = 3)
French Frigate Shoals Kauai (N = 34)
(N = 33)
Nihoa Oahu (N = 29)
(N = 32)
Lanai
(N = 1)
Northwest Hawaiian Islands (NWHI)
N = 315 Hawaii
(N = 32)
Johnston Atoll
(N = 34)

12. Study objectives
We aim to address the following questions:
(1) Is there genetic structure within the Hawaiian
archipelago?
(2) Is there genetic structure among other sampled
Pacific populations?
(3) Is there evidence of genetic exchange between
Hawaii and the rest of the Pacific?

13. Analysis of genetic structure
1) Haplotype and nucleotide diversity
2) Neutrality test statistics:
Tajima’s D and Fu’s Fs
3) Connectivity via φ ST values:
– Between all populations
– Between NWHI & MHI
– Between Hawaii and Pacific
4) mtDNA sequence divergence
5) Mismatch distribution analysis:
 Coalescence times (from τ estimates)
6) MIGRATE software analysis:
 number of migrants per generation

14. Analysis of genetic structure
1) Haplotype and nucleotide diversity
2) Neutrality test statistics:
Tajima’s D and Fu’s Fs
3) Connectivity via φ ST values:
– Between all populations
– Between NWHI & MHI
– Between Hawaii and Pacific
4) mtDNA sequence divergence
5) Mismatch distribution analysis:
 Coalescence times (from τ estimates)
6) MIGRATE software analysis:
 number of migrants per generation

15. Connectivity within Hawaiian islands
NO genetic structure in Hawaii
- O v e r a l l : φ S T = 0 . 0 1, P = 0 . 0
- MHI vs. NWHI: φ ST = -0.002, P = 0.65
- 38 haplotypes (HAP 1 + 2 every site)
- mtDNA sequence divergence= 0.1%

16. Connectivity within Hawaiian islands
φ ST = 0.01, P = 0.07 NO genetic structure in Hawaii
- O v e r a l l : φ S T = 0 . 0 1, P = 0 . 0
- MHI vs. NWHI: φ ST = -0.002, P = 0.65
- 38 haplotypes (HAP 1 + 2 every site)
- mtDNA sequence divergence= 0.1%

17. Connectivity within Hawaiian islands
φ ST = -0.002, P = 0.65 NO genetic structure in Hawaii
- O v e r a l l : φ S T = 0 . 0 1, P = 0 . 0
- MHI vs. NWHI: φ ST = -0.002, P = 0.65
- 38 haplotypes (HAP 1 + 2 every site)
- mtDNA sequence divergence= 0.1%

18. Connectivity within Hawaiian islands
NO genetic structure in Hawaii
Nm = 22.99
- O v e r a l l : φ S T = 0 . 0 1, P = 0 . 0
- MHI vs. NWHI: φ ST = -0.002, P = 0.65
- 38 haplotypes (HAP 1 + 2 every site)
- mtDNA sequence divergence= 0.1%
Number of migrants/generation:
From NWHI into MHI = 22.99 (0 to 132)
Nm = 35.19 From MHI into NWHI = 35.19 (0 to 162)

19. Direction of exchange appears primarily
to the NW rather than SE in Hawaii

20. Connectivity within Pacific islands
NO genetic structure in Pacific
MI - O v e r a l l : φ S T = 0 . 0 0 9 , P = 0 . 18
- 5 8 h a p lo t y p e s ( m a n y s in g le t o
KI
AS - mtDNA sequence divergence = 0.6%
MO
MI = Marshall Islands
AS = American Samoa
KI = Kiribati
MO = Moorea

21. Connectivity within Pacific islands
φ ST = 0.009, P = 0.18 genetic structure in Pacific
NO
MI - O v e r a l l : φ S T = 0 . 0 0 9 , P = 0 . 18
- 5 8 h a p lo t y p e s ( m a n y s in g le t o
KI
AS - mtDNA sequence divergence = 0.6%
MO
MI = Marshall Islands
AS = American Samoa
KI = Kiribati
MO = Moorea

22. Connectivity within Pacific islands
φ ST = 0.009, P = 0.18 genetic structure in Pacific
NO
MI - O v e r a l l : φ S T = 0 . 0 0 9 , P = 0 . 18
- 5 8 h a p lo t y p e s ( m a n y s in g le t o
KI
AS - mtDNA sequence divergence = 0.6%
MO
Number of migrants/generation:
MI = Marshall Islands
Mean migration rate within Pacific
AS = American Samoa
KI = Kiribati = 13.36 (0 to 66 CI)
MO = Moorea
NO BIAS IN MIGRATION DIRECTION

23. Connectivity between Pacific regions
Hawaii
Oahu
Lanai
Kauai
Nihoa
Necker
French Frigate Shoals
Hawaiian Archipelago Gardner Pinnacles
Maro Reef
Laysan
Lisianski
Pearl & Hermes Atoll
Midway
Kure ns
tio
Johnston Atoll
a
ut
m
2 5 Marshall Islands
Moorea
Kiribati Pacific Islands
American Samoa
Sequence divergence = 4.12 %
φ ST = 0.96, P < 0.0001
(DiBattista, Wilcox et al., 2011 JMB)

24. Photos by Jack E. Randall
Hawaiian A. nigroris, from Oahu Pacific A. nigroris, from Enewetak
Meristic Differences
Hawaiian Pacific
Dorsal Soft Rays 24 - 27 23 - 26
Anal Soft Rays 22 - 25 22 - 24
Anterior Gill Rakers 26 - 31 21 - 25
Posterior Gill Rakers 24 - 27 19 - 24
Randall, JE (1956), Pacific Science, 10:159-235.

25. Photos by Jack E. Randall
Hawaiian A. nigroris, from Oahu Pacific A. nigroris, from Enewetak
Meristic Differences
Hawaiian Pacific
Dorsal Soft Rays 24 - 27 23 - 26
Anal Soft Rays 22 - 25 22 - 24
Anterior Gill Rakers 26 - 31 21 - 25
Posterior Gill Rakers 24 - 27 19 - 24
Randall, JE (1956), Pacific Science, 10:159-235.

26. Species distribution map
Randall et al. in press, Pacific Science
Acanthurus nigros Günther
Acanthurus nigroris

27. Conclusions
• High gene flow over large distances:
 Hawaiian region: ~2600 km
 Pacific region: ~800 km
• Distinct barrier to gene flow between
Hawaii and the rest of the Pacific
• Two proposed surgeonfish species:
 Hawaiian endemic species
 Widespread Pacific species

28. The bigger picture?
Hawaiian endemics Widespread surgeonfish
Eble et al. 2011:
Indo-Pacific
Eble et al. 2009: Acanthurus
nigrofuscus Some genetic structure
Strong genetic structure
Ctenochaetus strigosus Eble et al. 2009:
North/West Pacific
Zebrasoma flavescens Some genetic structure
Present study:
No genetic structure Present Study:
Central Pacific
Acanthurus nigroris
No genetic structure
Acanthurus nigros

29. Acknowledgements
Thanks to Robert Toonen and Jeff Eble for multiple contributions to this
study.
This research was supported by the National Science Foundation grants
OIA0554657, OCE-0453167 and OCE-0929031 (BWB), OCE-0623678 (RJT),
and NOAA National Marine Sanctuaries Program MOA No. 2005-008/66882
(BWB & RJT).
We thank the Papahanaumokuakea Marine National Monument and co-trustees NOAA
Marine Sanctuaries, U.S. Fish and Wildlife Service (USFWS), and the State of Hawaii.
Paul Barber, Howard Choat, Pat Collins, Greg Concepcion, Jonathan Dale, Toby Daly-
Engel, John Earle, Michelle Gaither, Brian Greene, Matt Iacchei, Stephen Karl, Randall
Kosaki, Carl Meyer, Yannis Papastamatiou, Joshua Reece, Jennifer Schultz, Zoltan
Szabo, Tonatiuh Trejo-Cantwell, Jill Zamzow, and the crew of the R.V. Hi’ialakai
helped collect specimens. Aulani Wilhelm, Jo-Ann Leong, Hoku Johnson, Danielle
Carter, Daniel Polhemus, Randall Kosaki, Ann Mooney, Elizabeth Keenen, Kelly
Gleason, James Maragos, and the Coral Reef Research Foundation provided crucial
logistic assistance to this project. We thank Zoltan Szabo for valuable laboratory
assistance and protocol development, Sarah Daley, Rajesh Shrestha and Mindy
Mizobe of the HIMB EPSCoR core facility for their assistance with DNA sequencing,
John Randall, Stephen Karl, and all the members of the ToBo lab for their advice,
assistance, and support.