Biology Reference
In-Depth Information
name for every entry, but all relevant alternates should be identified within the
pool of locality records for each species. This should facilitate recognition of the
older literature passages that differ from current nomenclature.
2.
Locality
. Locality of introduction is typically a defined political jurisdiction,
usually a country, but for the United States and Canada I subdivided jurisdiction
by state or province. As well, because political jurisdictions are arbitrary, I also
tracked data separately for biologically important islands or island groups that
are parts of larger, distinct countries. Importance, in this case, was determined
by the biogeographical significance of the island or island group irrespective of
its current political affiliation. So, for example, records for the Galapagos are
treated separately than those for the remainder of Ecuador, those for the Ryukyus
separately than for the remainder of Japan, Sardinia and Sicily separate from
Italy, etc. Doing this allows for better assessment of the degree to which intro-
ductions to islands are more successful than those to continental areas.
I excluded the following from the database: (1) conservation re-introductions to
a species' native range; (2) releases of animals from one part of their native range
to another, unless a distinctly different genetic lineage (operationally, typically
involving a different subspecies) or source population was unambiguously
involved; and (3) experimental introductions to tiny unoccupied islands in the
midst of a species' native range. The first is irrelevant to assessing the degree to
which reptile and amphibian introductions serve as a conservation threat, as
opposed to a remedy. The second is usually unknowable and rarely reported in the
literature (see Eckstein and Meinig, 1989; Münch, 1992 for exceptions). The third
is likely a reflection of colonization or extinction stochasticity, is biogeographi-
cally meaningless, and adds nothing to my analyses. So, for example, I do not
include in the database experimental introductions of
Anolis sagrei
to several
uninhabited islets in the midst of its native range in the Bahamas (Schoener and
Spiller, 1996, 1999; Losos and Spiller, 1999, 2005),
Podarcis pityusensis
to Dau
Gran in the Balearic Islands (Böhme and Eisentraut, 1981), or
Podarcis sicula
to
coastal islands in Croatia (Radovanovi´, 1959, 1965; Nevo et al., 1972). In each
case, the species in question is native to the immediately adjacent mainland or
surrounding islands and biogeographic patterns remain unobscured. I do include
all other introductions to islands, even if near a species' native range, because the
introduction is potentially of some biogeographical significance. For example,
I include the introductions of
Podarcis sicula
to the Aeolian Islands of southern
Italy and
Sauromalus
species in the Sea of Cortez because in each case biogeo-
graphic patterns are potentially obscured by the introduction and/or endemic congeners
are potentially affected by the introductions.
These distinctions can admittedly be somewhat arbitrary, and two problematic
issues remain, although relatively few taxa are involved. First, I do include in the
table introductions of species to areas outside of their historic ranges even if those
areas were inhabited prehistorically but modern presence in the area is compellingly
ascribed to human introduction. The primary example of this is
Emys orbicularis
,
which inhabited virtually all of Europe during xerothermic eras but has been absent
