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1684 C. Gubili et al. Historical dispersal of white sharks
absence of these Mediterranean haplotypes from our anonymous referees for helpful comments. In memoriam:
comprehensive genetic analyses of South African white Dave Noble (d. 20 October 2010)—always and forever a
sharks [18,50], argues for a disjunct distribution of the support and inspiration.
Indo-Pacific clade.
As a species exhibiting strong natal female philopatry,
these sharks probably constitute a sink population
REFERENCES
established at a time of extreme climate change. Conse-
1 Myers,R.A., Baum, J.K., Shepherd,T.D., Powers,S.P.&
quently, if the haplotypes recovered truly reflect white Peterson, C.H.2007Cascading effectsofthe loss of
shark diversity there would seem little potential for apex predatory sharks from a coastal ocean. Science 315,
replacement females to enter and establish in the 1846–1850. (doi:10.1126/science.1138657)
Mediterranean should the current population become 2 Crowder, L. & Norse, E. 2008 Essential ecological
unsustainable. Some migration of white sharks into the insights for marine ecosystem-based management and
Mediterranean cannot be dismissed, but they are rare in marine spatial planning. Mar. Policy 32, 772–778.
the north-eastern Atlantic [51], with most captures (doi:10.1016/j.marpol.2008.03.012)
from oceanic islands, particularly the Azores, of mature 3Bo ´nfil, R., Mey ¨er, M., Scholl, M. C., Johnson, R.,
O’Brien, S., Oosthuizen, H., Swanson, S., Kotze, D. &
individuals. An occasional visitor [52], its origins and
Paterson, M. 2005 Transoceanic migration, spatial
limits of distribution in this region remain poorly known
dynamics, and population linkages of white sharks.
[11]. Additionally, no information is available from the
Science 310, 100–103. (doi:10.1126/science.1114898)
Straits of Gibraltar, where interchange between the Atlan- 4 Gore, M. A., Rowat, D., Hall, J., Gell, F. R. & Ormond,
tic and the Mediterranean would be most apparent. In R. F. 2008 Transatlantic migration and deep mid-ocean
contrast, available sightings suggest that large individuals diving by basking shark. Biol. Lett. 4, 395–398. (doi:10.
are resident at eastern basin Mediterranean sites for a year 1098/rsbl.2008.0147)
or more [53], with catches year round. Hence, migration 5 Engelhaupt, D. et al. 2009 Female philopatry in coastal
between these populations, while not impossible, seems basins and male dispersion across the North Atlantic in
unlikely. Currently, there is no available tagging data for a highly mobile marine species, the sperm whale (Physeter
Mediterranean white sharks, and recent analysis of a macrocephalus). Mol. Ecol. 18, 4193–4205. (doi:10.1111/
j.1365-294X.2009.04355.x)
few tagged north-western Atlantic individuals indicates
6 Skomal, G. B., Zeeman, S. I., Chisholm, J. H., Summers,
migration along the US coast (Cape Cod, 2009; G.
E. L., Walsh, H. J., McMahon, K. W. & Thorrold, S. R.
Skomal 2010, personal communication) rather than
2009 Transequatorial migrations by basking sharks in the
across the Atlantic. Indeed, white sharks are encountered Western Atlantic Ocean. Curr. Biol. 19, 1019–1022.
most frequently in continental shelf waters from Cape (doi:10.1016/j.cub.2009.04.019)
Cod to Cape Hatteras in the north-western Atlantic 7 Holts, D. B. & Bedford, D. W. 1993 Horizontal and
Ocean [49], showing a more seasonal (January–April) vertical movements of the shortfin mako shark, Isurus oxy-
presence west of Florida [54]. Nevertheless, even if rinchus, in the southern California Bight. Aust.J.Mar.
males from the Atlantic occasionally mate with Mediter- Freshw. Res. 44, 901–909. (doi:10.1071/MF9930901)
ranean females, the natal philopatry of the latter 8 Wilson, S. G., Polovina, J. J., Stewart, B. S. & Meekan,
M. G. 2006 Movements of whale sharks (Rhincodon
guarantees that continuity of the Mediterranean stock
typus) tagged at Ningaloo Reef, Western Australia. Mar.
remains inextricably linked to the fate of these anomalous
Biol. 148, 1157–1166. (doi:10.1007/s00227-005-0153-8)
haplotypes. Future analyses incorporating both nuclear
9 Sherrill-Mix, S. A., James, M. C. & Myers, R. A. 2008
and mitochondrial markers in larger population samples Migration cues and timing in leatherback sea turtles.
will determine the likelihood of male- and female- Behav. Ecol. 19, 231–236. (doi:10.1093/beheco/arm104)
mediated gene flow into the Mediterranean, determining 10 Corten, A. 2001 Northern distribution of North Sea her-
if this is truly a closed population established by infre- ring as a response to high water temperature and/or low
quent historical migration of ‘founder’ females. food abundance. Fish. Res. 50, 189–204. (doi:10.1016/
A key member of a vulnerable ecosystem, currently of S0165-7836(00)00251-4)
huge commercial and scientific value, the Mediterranean 11 Fergusson, I. K. 1996 Distribution and autoecology of
the white shark in the Eastern North Atlantic and the
white shark population may be considered a consequence
Mediterranean Sea. In Great white sharks: the biology of
of historical accident and female philopatry, revealing it to
Carcharodon carcharias (eds A. P. Klimley & D. G.
be at greater risk of local extirpations than previously
Ainley), pp. 321–345. San Diego, CA: Academic Press.
thought. Demise of this top predator in a relatively 12 Kabasakal, H. & Kabasakal, E. 2004 Sharks captured by
small and contained sea may precipitate a catastrophic commercial fishing vessels off the coast of Turkey in the
trophic cascade, already recorded in more robust ecosys- northern Aegean Sea. Ann. Ser. Hist. Nat. 14, 171–180.
tems following depletion of populations of large sharks 13 De Maddalena, A. 2005 The great white shark,
[1]. It is disturbing to speculate about the disproportion- Carcharodon carcharias (Linnaeus, 1758) of the Settala
ate deleterious effects white shark loss may have on Museum, Milan. Bollettino del Museo Civico di Storia
ecosystem stability in this relatively enclosed and econ- Naturale di Venezia 57, 149–154.
omically important environment. 14 De Maddalena, A. 2006 A catalogue of great white sharks
Carcharodon carcharias (Linnaeus, 1758) preserved in
European museums. J. Natl Mus., Nat. History Ser.
This work was supported by Aberdeen University, the 175, 109–125.
Marine Biological Association, Bog˘azic¸i University and the 15 Condorelli, M. & Perrando, G. C. 1909 Notizie sul
Scientific and Technological Research Council of Turkey Carcharcdon carcharias L., catturato nelle acque di
(TU ¨ BI ˙ TAK). We are also grateful to Eleonora de Sabata Augusta e considerazioni medico-legali su resti umani
(MedSharks, Italy) for supplying a sample, Nicolas Pade trovati nel suo tubo digerente. Soc. Zool. Ital. Boll. 1909,
for porbeagle sequences, Colin Macleod and two 164–183.
Proc. R. Soc. B (2011)