Introduction Patterns - Alien Reptiles and Amphibians - page 34

the entire success of the Typhlopidae is due to the success of one species,
Ramphotyphlops braminus , which is parthenogenic and, hence, far more likely to
establish populations subsequent to introduction than any other species in the data-
set. As another example, the apparent success of the Proteidae is inflated by the fact
that several of its successful “introductions” actually stem from natural dispersal
across jurisdictional boundaries from an original introduction. Nonetheless, it is
clear that families that have undergone a large number of introduction events can
vary widely in their establishment success, a topic that is analyzed in some detail
by Bomford et al. (in press) for these same data.
Pathway Variation
Ten pathways accounted for the overwhelming majority of all herpetological introduc-
tions, whether pathway importance was measured by total number of introductions
involved (Fig. 2.8) or by number of species involved (Fig. 2.9). Of these pathways, six
predominate in importance, whether all introductions are considered (Figs. 2.8 and
2.9) or only introductions leading to successful establishment are examined (Figs. 2.10
and 2.11). Hence, the remaining discussion will focus on those six pathways most
involved in alien herp movements: biocontrol, cargo, food, nursery, pet trade, and
“intentional”. Each of these requires definition prior to continued discussion.
“Biocontrol” refers to instances of species transported and deliberately released
in the hopes of controlling some perceived pest, typically a pest of agriculture but
sometimes including house pests such as cockroaches. The best-known example of
this pathway among reptiles and amphibians is the widespread introduction of Bufo
marinus around the tropics for the control of a variety of boring beetles that attack
sugar cane, Saccharum spp. (Easteal, 1981). “Cargo” refers to accidental transport
Fig. 2.8 Relative importance of pathways of herpetofaunal introduction as measured by total
numbers of introduction events