Adapted dandelions trade dispersal for germination upon root herbivore attack

Abstract

A plant's offspring may escape unfavourable local conditions through seed dispersal. Whether plants use this strategy to escape insect herbivores is not well understood. Here, we explore how different dandelion ( Taraxacum officinale agg.) populations, including diploid outcrossers and triploid apomicts, modify seed dispersal in response to root herbivore attack by their main root-feeding natural enemy, the larvae of the common cockchafer Melolontha melolontha. In a manipulative field experiment, root herbivore attack increased seed dispersal potential through a reduction in seed weight in populations that evolved under high root herbivore pressure, but not in populations that evolved under low pressure. This increase in dispersal potential was independent of plant cytotype, but associated with a reduction in germination rate, suggesting that adapted dandelions trade dispersal for establishment upon attack by root herbivores. Analysis of vegetative growth parameters suggested that the increased dispersal capacity was not the result of stress flowering. In summary, these results suggest that root herbivory selects for an induced increase in dispersal ability in response to herbivore attack. Induced seed dispersal may be a strategy that allows adapted plants to escape from herbivores.

How plant–soil feedbacks influence the next generation of plants

“…Effects that manifest only during the critical early life stages of a plant may be important (Germain & Gilbert, 2014; Walter, Harter, Beierkuhnlein, & Jentsch, 2016), regardless if such effects continue to impact on plant performance later in life. For example, responses to belowground antagonists that alter seed dispersal (Bont et al, 2020) or changes to soil chemistry that could affect germination rates (Figure 5) can be integral in determining recruitment and establishment success. Further, another factor that may have confounded potential intergenerational PSF effects in this experiment is the dynamic soil environment experienced by the parent plants.…”

“…Intergenerational effects can manifest through constitutional changes, such as changes in number, size or nutrient concentration of seeds (Germain & Gilbert, 2014), resulting in alterations to number of seedlings, dispersal or initial growth, respectively. For example, if a plant experiences intense belowground herbivory, it may produce lighter seeds that disperse further from the parent plant, thereby germinating in more favorable soils (Bont et al, 2020).…”

Competition–colonisation trade‐offs are found among but not within wind‐dispersed Pinus species

“…Eriksson & Jakobsson, 1999; Maron et al., 2021; Muthukrishnan et al., 2020; Turnbull et al., 1999; Wyse & Hulme, 2021b). In contrast, the existence of a competition–colonisation trade‐off within individual species is much less well studied and the limited evidence to date is inconsistent, with cases both arguing for (Bont et al., 2020; Huang et al., 2015) and against (Tabassum & Leishman, 2018) a trade‐off. Yet, understanding whether competition–colonisation trade‐offs exist within species is essential to interpret and predict spatial patterns in seedling recruitment, population dynamics and species evolution at range margins or invasion fronts (Courbaud et al., 2012; Urquhart & Williams, 2021).…”

Sepal Identity of the Pappus and Floral Organ Development in the Common Dandelion (Taraxacum officinale; Asteraceae)

“…We investigated the development of the pappus in dandelion in detail, aiming to develop the use of dispersal capacity for urban evolution studies in plants. The pappus plays an important role in the dispersal of the seeds and fruits of the Asteraceae [ 1 , 2 ], and variation in the pappus may directly lead to differences in dispersal ability [ 3 , 4 ] allowing plants to anticipate changing environments. To measure such changes and determine how quickly they occur in response to changing environments, we should first characterize pappus development and investigate pappus–sepal homology.…”

“…This suggests that the number of pappus parts plays an important role in dispersal capacity. Dispersal potential of T. officinale fruits was found to be 1–3 m on average, to be positively correlated to pappus part length, and to be negatively correlated to fruit weight [ 2 , 3 ].…”