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Fig. 2.35 Cumulative growth in donor region contribution to global reptile and amphibian intro-
ductions. Asia = red, Australia = green, Caribbean = pink, Europe = yellow, and North America
= blue
Table 2.6 Exponential growth rates for regions donating the greatest numbers of introductions
Pathway
Time span
Growth equation
R 2
Doubling time (years)
Caribbean
1850-1999
y = 1.4440e 0.2329x
0.9683
29.6
Europe
1850-1999
y = 12.295e 0.1932x
0.9909
35.7
North America
1900-1999
y = 26.573e 0.3031x
0.9633
22.8
growth as does occur (Table 2.6) is consistent with the hierarchy in dominance of
donor regions seen in Fig. 2.35. The greater variation in growth patterns seen for
donor regions compared to the strictly exponential patterns seen earlier for recipient
regions (Fig. 2.22, Table 2.5) likely reflects the importance that legal and aesthetic
particularities can have in restricting what is available for transport from a single
region at any particular time. In contrast, importations to a region can average
across a diversity of source areas, smoothing out availability variation in source
areas, and thereby keeping growth at a more consistently exponential rate.
General
Although I have identified a total of ten pathways by which alien herpetofauna
are transported, and six major pathways that account for most of this transport,
several of these are clearly related to each other. For example, two of the major
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