Life-history theory and management - Ecological Applications: Toward a Sustainable World - page 69

Table 3.2 Te st s of the
degree to which species
variables correlate with
the likelihood of parrot
species being trans-
ported from their native
range, released into a
new area and establish-
ing in the new location.
(Modifi ed from Cassey
et al., 2004.)

Variables Transport Release Establishment

Ecological fl exibility

Diet breadth + * + * + **

Altitudinal range + *

Latitudinal range + *** + ***

Life history

Body mass + *

Annual fecundity

Age at maturity

Fledging period + **

Migration − * − **

Dichromatism + *

Movement

International trade + *** + *** + **

To be kept in captivity + *** + ***

To be kept as pets + *** + ***

Population size/extent

Threat status − ** − *

Population size + ** + *

Geographical range + *** + **

+ , negative relationship.

Asterisks indicate the level of statistical signifi cance of the results for each trait in each year - more asterisks
mean a greater level of confi dence in the result: * p

, Positive relationship; −

< 0.05, ** p < 0.01, *** p < 0.001, blank not signifi cant.

Fig. 3.4 Increase with
time in the cumulative
number of alien plants
in the Czech Republic
corresponding to
Grime's CSR strategy
combinations. Refer to
Box 3.1 for defi nitions
of C (competitive), S
(stress-tolerant) and R
(ruderal). (From Pysek
et al., 2003.)

160

C
CR

140
120
100
80
60
40
20
0
1750

R

CSR
CS
SR

1800 1850 1900 1950 2000

and species traits, Pysek's team considered type of life history (annual, biennial,
herbaceous perennial, woody perennial), fl owering time, mode of dispersal (water,
wind, animal assisted) and Grime's CSR strategy. The strongest relationship was
with Grime's strategy: species having the unusual but highly fl exible CSR strategy
(most features of competitiveness, stress tolerance and ruderality incorporated in a
single organism) arriving earlier than CS species, which in turn arrived earlier than
C or CR species. The pattern of accumulation of species with each strategy is shown
in Figure 3.4. (Note that the early arrival of CSR strategists is not obvious in this
fi gure because of the small number of species of this type.) By far the most com-