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(Capula, 1993). These events have led to some genetic introgression on each island,
and evidence indicates there was hybridization with P. raffonei prior to its extinc-
tion on Lipari as well (Capula, 1993). To what extent genetic introgression has
contributed to the decline of P. raffonei beyond that attributed to the competitive
effects noted earlier remains unknown.
Hybridization between Iguana delicatissima and I. iguana is documented and is
argued to be contributing to the displacement of the former in Guadeloupe and les
Îles des Saintes (Day and Thorpe, 1996; Day et al., 2000; Breuil, 2000a, b, 2002).
It remains uncertain that I. iguana is alien to this region but it highlights the potential
for similar problems in nearby areas (e.g., northern Lesser Antilles) where it
certainly is not native.
Some populations of Anolis distichus may originally have been native to Florida
(L.D. Wilson and Porras, 1983, but see A. Schwartz, 1968a for a contrary opinion)
and were given the designation A. d. floridanus (H.M. Smith and McCauley, 1948).
But three other subspecies of A. distichus have been introduced to Florida (W. King
and Krakauer, 1966; Bartlett, 1995a), and hybridization between one of these,
A. d. dominicensis , and the presumptive native has been sufficient to largely obliter-
ate the distinctiveness of the latter, creating instead a continuum of phenotypes
having no geographic structure (Miyamoto et al., 1986). Mitochondrial DNA evi-
dence also supports a history of extensive hybridization among three or four lineages of
A. distichus in this region (Kolbe et al., 2007a). Thus, the original population
of A. distichus inhabiting Florida in the 1940s is now extinct and replaced by a
variable hybrid swarm of largely alien composition. Whether this represents loss of
a unique lineage or not is unknown.
Hybridization between native Anolis carolinensis and alien A. porcatus has also
occurred in southern Florida (Kolbe et al., 2007a), but the magnitude of any genetic
impact on the native remains unknown.
Hybridization with introduced Trachemys scripta may be a threat to the endemic
T. stejnegeri malonei of Great Inagua Island (Mealey et al., 2002). If one believes
the argument of Lee and Ross (2001) that T. terrapin is native to Grand Bahama
Bank and not to Jamaica, the same threat would be posed by introduced T. scripta
and T. stejnegeri on the islands of that bank (Lee, 2004, 2005), where hybrid
swarms have resulted from past introductions (Seidel and Adkins, 1987; Seidel,
1988). Alien T. scripta elegans are widely hybridizing with native T. scripta scripta
in Florida (Bartlett and Bartlett, 1999; Aresco and Jackson, 2006) and Virginia
(Mitchell, 1994), but the degree of genetic pollution in these populations is not yet
quantified. Introduced Cuora flavomarginata interbreed with the native species
Geoemyda japonica in the Ryukyu Islands, and hybrids are moderately frequent
on the same island between native Protobothrops flavoviridis and the intro-
duced P. elegans (Nishimura and Akamine, 2002; Ota, 2002d; Ota and Hamaguchi,
2003). In both cases, the genetic integrity of the natives may be threatened by inter-
breeding with closely related aliens. Alien subspecies and DNA haplotypes of Emys
orbiculari s have been widely distributed around much of Europe (Lenk et al., 1998;
U. Fritz et al., 2004), posing the threat of genetic contamination or swamping of
local populations (Kaltenegger, 2006).
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