Does Darwin’s Naturalization Hypothesis Explain Fish Invasions?

Abstract

Darwin's naturalization hypothesis predicts that introduced species tend not to invade areas containing congeneric native species, because they would otherwise compete with their close relatives and would likely encounter predators and pathogens that can attack them. An opposing view is that introduced species should succeed in areas where native congeners are present because they are more likely to share traits that pre-adapt them to their new environment. A test of both these hypotheses using data on fish introductions from several independent regions fails to support either viewpoints. In contrast to studies of nonindigenous plants, our results suggest that taxonomic affiliation is not an important general predictor of fish invasion success.

Establishment of introduced reptiles increases with the presence and richness of native congeners

“…These results supported the pre-adaptation hypothesis rather than Darwin's naturalization hypothesis. Of the two previous global assessments of congener effects on animal taxa, one found support for the pre-adaptation hypothesis (Tingley, Phillips and Shine, 2011), and the other found no support for either hypothesis (Ricciardi and Mottiar, 2006). Our results were similar to those of Tingley, Phillips and Shine's (2011) that analyzed amphibian invasions, although these authors incorporated more variables.…”

“…The two invasion hypotheses were tested for all reptiles globally, for islands and continents, and for each region (Africa, Asia, Caribbean, Europe, Oceania, North America, and South America) separately using Fisher's exact test (as in Ricciardi and Mottiar, 2006). Mesoamerica did not have any unsuccessful introductions, so we were unable to conduct a Fisher's exact test.…”

“…We are aware of only two studies that have tested these hypotheses with animals at a global scale. Ricciardi and Mottiar (2006) did not find support for either hypothesis for fish invasions, and Tingley, Phillips and Shine (2011) tested the hypotheses for amphibians using both congener presence and richness, and found support for the pre-adaptation hypothesis. Van Wilgen and Richardson (2011) conducted the first test of these hypotheses for reptiles in Florida and California, USA, and showed support for the naturalization hypothesis.…”

A test of Darwin's naturalization hypothesis in the thistle tribe shows that close relatives make bad neighbors

“…Quantifiable measures that can provide robust predictions are therefore required (32), and phylogenetic relationships between native and introduced taxa may reveal patterns that invoke testable hypotheses that could not be derived from examining species traits alone (33). Distinct sets of traits evolve in response to environmental conditions, which in turn reflect past and present selection pressures and are therefore expected to differ not only among geographic regions and local communities (34), but also among evolutionary lineages.…”

“…The enemy escape hypothesis also supports this view (42,43). An alternative, opposing hypothesis is that relatedness to native taxa may convey degrees of preadaptation to the conditions of the invaded environment, rendering close relatives more likely to succeed once introduced (32,39,44).…”