Differential effect of inter‐ and intraspecific competition on the performance of invasive and native Taraxacum species

Abstract

Inter‐ and intraspecific competitive abilities are significant determinants of invasive success and the ecological impact of non‐native plants. We tested two major hypotheses on the competitive ability of invasive species using invasive (Taraxacum officinale) and native (T. platycarpum) dandelions: differential interspecific competitive ability between invasive and native species and the kin recognition of invasive species. We collected seeds from two field sites where the two dandelion species occurred nearby. Plants were grown alone, with kin (plants from the same maternal genotype) or strangers (plants from different populations) of the same species, or with different species in a growth chamber, and the performance at the early developmental stage between species and treatments was compared. The invasive dandelions outcompeted the native dandelions when competing against each other, although no difference between species was detected without competition or with intraspecific competition. Populations of native species responded to interspecific competition differently. The effect of kinship on plant performance differed between the tested populations in both species. A population produced more biomass than the other populations when grown with a stranger, and this trend was manifested more in native species. Our results support the hypothesis that invasive plants have better competitive ability than native plants, which potentially contributes to the establishment and the range expansion of T. officinale in the introduced range. Although kin recognition is expected to evolve in invasive species, the competitive ability of populations rather than kinship seems to affect plant growth of invasive T. officinale under intraspecific competition.

Differences in growth and competition between plants of a naturalized and an invasive population of Bunias orientalis

“…In addition, JE_IN plants had a higher SLA when grown in intrapopulation than in interpopulation competition or grown alone. These responses are obviously species-specific; in contrast to the findings in B. orientalis, SLA did not differ between invasive Taraxacum officinale grown in intrapopulation competition or alone (Lee et al, 2021).…”

“…Under conditions of reduced light availability, plants may allocate more biomass to the shoots, produce larger leaves and enhance the elongation of stems (Weiner, 1993;Westoby et al, 2002). Such larger vegetative expansion has also been found in invasive populations of other species in both competition and competition-free studies (Chun et al, 2010;Lee et al, 2021). As for aboveground biomass, the number and length of leaves of B. orientalis were reduced when plants were grown in competition, indicating that competition can reduce fitness-related traits (Craine & Dybzinski, 2013;Harper, 1977).…”

“…Interspecific competition is considered as an important factor driving plant invasions (Crawley et al, 1990;Sheppard, 2019), but competitive ability can also differ significantly within species among populations (Huang & Peng, 2016;Lin et al, 2015), as shown, for example, for different invasive populations of Taraxacum officinale and Ageratina adenophora or native populations of T. platycarpum (Lee et al, 2021;Zheng et al, 2015). Young founder populations exploiting new habitats may initially be less competitive.…”

“…Plant competition should be determined by investigating both intraspecific and interspecific competition because both affect the distribution pattern of non‐native plants in their introduced range (Bossdorf et al., 2004 ; Gioria & Osborne, 2014 ; Vilà & Weiner, 2004 ). Interspecific competition is considered as an important factor driving plant invasions (Crawley et al., 1990 ; Sheppard, 2019 ), but competitive ability can also differ significantly within species among populations (Huang & Peng, 2016 ; Lin et al., 2015 ), as shown, for example, for different invasive populations of Taraxacum officinale and Ageratina adenophora or native populations of T. platycarpum (Lee et al., 2021 ; Zheng et al., 2015 ). Young founder populations exploiting new habitats may initially be less competitive.…”

Invasive freshwater snails are less sensitive to population density than native conspecifics

“…antipodarum ), in Polecat Creek in Grand Teton National Park, Wyoming (Riley & Dybdahl, 2015 ). It is thus perhaps not surprising that population density effects have been relatively well studied at the interspecific scale, including growth rate as a function of population density in invasive Taraxacum officinale versus native Taraxacum platycarpum (Lee et al., 2021 ) and in invasive Physa acuta versus native Physa fontinalis (Früh et al., 2017 ). Our study, which is instead focused on intraspecific density‐dependent effects, is relevant to understanding why some lineages become successful invaders while others do not, providing important insights into the evolution and ecology of biological invasions.…”