Postintroduction evolution contributes to the successful invasion of Chromolaena odorata

Abstract

The evolution of increased competitive ability (EICA) hypothesis states that, when introduced in a novel habitat, invasive species may reallocate resources from costly quantitative defense mechanisms against enemies to dispersal and reproduction; meanwhile, the refinement of EICA suggests that concentrations of toxins used for qualitative defense against generalist herbivores may increase. Previous studies considered that only few genotypes were introduced to the new range, whereas most studies to test the EICA (or the refinement of EICA) hypotheses did not consider founder effects. In this study, genetic and phenotypic data of Chromolaena odorata populations sampled across native and introduced ranges were combined to investigate the role of postintroduction evolution in the successful invasion of C. odorata. Compared with native populations, the introduced populations exhibited lower levels of genetic diversity. Moreover, different founder effects events were interpreted as the main cause of the genetic structure observed in introduced ranges. Three Florida, two Trinidad, and two Puerto Rico populations may have been the sources of the invasive C. odorata in Asia. When in free of competition conditions, C. odorata plants from introduced ranges perform better than those from native ranges at high nutrient supply but not at low nutrient level. The differences in performance due to competition were significantly greater for C. odorata plants from the native range than those from the introduced range at both nutrient levels. Moreover, the differences in performance by competition were significantly greater for putative source populations than for invasive populations. Quantities of three types of secondary compounds in leaves of invasive C. odorata populations were significantly higher than those in putative source populations. These results provide more accurate evidence that the competitive ability of the introduced C. odorata is increased with postintroduction evolution.

Decreased coevolutionary potential and increased symbiont fecundity during the biological invasion of a legume‐rhizobium mutualism

“…2019; Li et al. 2020). Despite the fact that most invasive species engage in mutualism, we know little about how invasion affects the evolution of positive species interactions (Richardson et al.…”

“…Our study assesses the net effect of many stages of biological invasion on symbiotic interactions, integrating the evolutionary changes that can occur throughout the invasion process (Zenni et al 2017). Our approach does not determine whether differences between invaded-and native-range symbioses are due to effects of initial colonization (Brown et al 2014) or due to subsequent years of evolution in separate ranges (Li et al 2020). Genomics and historical records suggest that M. polymorpha and E. medicae were cointroduced to North America from the Mediterranean in the 1700s (Wing 1912;Porter et al 2018).…”

“…2014) or due to subsequent years of evolution in separate ranges (Li et al. 2020). Genomics and historical records suggest that M. polymorpha and E. medicae were cointroduced to North America from the Mediterranean in the 1700s (Wing 1912; Porter et al.…”

Novel chemicals engender myriad invasion mechanisms

“…Higher amounts of odoratin in non-native ranges provide greater competitive advantages (Zheng et al, 2015) Acutellerin-4 0 ,6,7-trimethy ether, 4 0 ,5,6,7tetramethoxyflavone, isosakuranetin, 3,5-dihydroxy-7,4 0 -dimethoxyflavone, dihydrokaempferol-3-methoxy ether, and kaempferide-4 0 -methoxy ether Greater amounts of flavonoids in the non-native range provide competitive advantages and better defence against soilborne pathogens (Li et al, 2020) Root leachates Root leachates of C. odorata can drive accumulation of native soil pathogens (Mangla et al, 2008) Centaurea diffusa (native to Europe; invasive in North America)…”

“…In another study, Li et al . (2020) found that invasive populations of C . odorata produced greater quantities of phenolic compounds; some of these phenolic compounds confer stronger defence and others may suppress native species (Table 1).…”