Biology Reference
In-Depth Information
But claims for introduction pathway were not explicitly made by some authors
for several areas in the introduced range of this species; thus, I did not ascribe a
pathway for those areas. Occasionally, species have been repeatedly introduced
to a particular jurisdiction for multiple reasons, and in these instances each docu-
mented or claimed reason is provided, as well as the minimum number of times
that pathway was utilized, if known or liable to estimation. If a single introduc-
tion was done for multiple reasons, both are listed within braces. In those few
instances in which introduction pathway is uncertain but is narrowed down to a
couple options, both options are listed within brackets. Parenthetical numbers
following a pathway designation indicate the minimum number of introductions
that are claimed or implied for that pathway. If no number is provided, the path-
way was either generally mentioned in reference to some introduction but not
clearly associated with any particular introduction event (if multiple events
occurred), or is unambiguously assigned when only a single introduction
occurred. Pathway designations should be self-explanatory with one exception.
As explained in Chapter 2, I have used the pathway designation “intentional” to
denote those introductions known to have been deliberately made by individuals
but without fitting into one of the other deliberate categories of introduction
(e.g., for biocontrol or food use). These “intentional” introductions have often
been noted or implied as being done out of personal aesthetic interest, but fre-
quently motives are unspecified although likely to derive from some form of
aesthetic satisfaction.
6.
Date
. Date of introduction is provided when known or liable to close estimation,
whether done explicitly by an original author or done by me based on data an
author provided. Dates of single specimens of obvious pet animals that never
formed established populations were typically approximated as the date of dis-
covery or the previous year, based on the assumption that most such animals do
not survive for extended periods in most jurisdictions. Multiple dates for multi-
ple introductions are recorded when known. Only introductions from outside the
boundaries of the jurisdiction in question are included; dates of subsequent dis-
persal of animals to new localities within the jurisdiction are not tracked.
Approximate date of entry into a jurisdiction by normal dispersal of animals
from a naturalized population in an adjacent jurisdiction are shown in brackets;
those dates were excluded frm the pathway analyses.
In the pathway analyses of Chapter 2, dates were grouped by decade, beginning
from 1850, so analytic methods are robust to some imprecision in date estimation.
In many cases, dates of introduction cannot be estimated or are insufficiently pre-
cise to be unambiguously assigned to decade. Such records were excluded from
calculations of pathway development through time. I made exceptions for two
studies (Kraus and Cravalho, 2001; Eterovic and Duarte, 2002) that each presented
many introduction records for a date range that spanned several years of the 1990s
but only the first few months of 2000. In those two cases, I counted all introductions
as falling into the 1990s so as to increase the data available for analyses. Although
this is not exactly correct (one might expect 5 of 76 introductions in São Paulo
