The porcupine as “Little Thumbling”: the role of Hystrix cristata in the spread of Helianthus tuberosus

The spread of alien invasive plants deserves strong and applied attention by conservation biologists, because it is regarded as one of the main causes of loss of native biodiversity. Herbivore species may be involved in the dispersal of invasive plants through zoochory. The Jerusalem artichoke Helianthus tuberosus is an invasive species in Europe, which has been introduced from North America and has shown a rapid spread in newly colonized areas. Crested porcupine Hystrix cristata mainly feed on this species (seeds and tubers) during its flowering period (i.e., late summer, early autumn) and it is suggested to be responsible for its spread through endozoochory. In this paper, the germination rate of the Jerusalem artichoke from faecal pellets of crested porcupines was analysed. Faecal pellets, collected between September and November 2016, were left to germinate at environmental conditions in sterile potting soil. After two weeks, germinated seedlings were genetically identified through DNA barcoding analyses. We reported the first case of endozoochory by the crested porcupine. The results showed a low germination rate (i.e., 16.7% out of 12 excrements), possibly because the digestive tract of crested porcupines affects the propagule viability. Despite this, the Jerusalem artichoke is showing a rapid and alarming increasing trend in our study area, suggesting that a potential role by wildlife may have been occurred. Given the high invasive potential of this plant species, further researches are required to assess and quantify the potential role of herbivores as dispersal agents.