Two important
goals of invasion science have been to identify species traits that facilitate
invasion and to identify landscape characteristics that may make a region
receptive to invasions. The inland waters of California are highly invaded and
particularly amenable to studying the process of invasion using freshwater
fishes. To address the above issues, we generated
a data set on fish invasions across watersheds in California.
To examine factors that might predict which species would invade we used
an information-theoretic approach to evaluate sets of hypotheses derived from
the invasion literature. Our results
indicate establishment is best predicted by a suite of factors, spread is best
predicted using measures of propagule pressure and physiological
tolerance, and impact is best predicted using a measure of propagule
pressure and prior invasion success. To
examine landscape characteristics, we used canonical correspondence analysis and
an information-theoretic approach to examine the numbers of non-native fishes
in California
watersheds. Our results indicate that, anthropogenic changes (urban development,
water diversions, aqueducts and agriculture) influenced the spatial patterns of
invasion. In total our results suggest the
complex nature of many introductions resists simple generalization, but results
from analyses like this can guide and inform management decisions.