Can camels disperse seeds of the invasive tree Prosopis juliflora?

Abstract

Summary Endozoochory has been recognised as the most important dispersal mechanism in invasive Prosopis species, because their sugary, tasty pods attract animals and because some of their seeds remain intact after passing through some animals' digestive systems. In this study, we evaluated the role of the camel (Camelus dromedarius) as a potential disperser of the seeds of invasive tree Prosopis juliflora. Four camels of similar weight (ca. 400 kg) and age (ca. 2 years) were each fed with 70 fruits (1000 seeds approximately) of P. juliflora, which were retrieved from the camels' dung at 24‐h intervals for 4 days. The seeds retrieved were tested for germination and viability, along with seeds not eaten by the camels, with and without pericarp. Less than 3% of the seeds eaten were retrieved from the camels' dung. Most of the seeds (74%) were retrieved between 24 and 72 h after ingestion. The passage through the camel gut significantly accelerated and increased seed germination of P. juliflora in comparison with uneaten seeds covered with pericarp (48–75% and 15% respectively). While gut passage liberated P. juliflora seeds from the pericarp, increasing and accelerating their germination, the viability of seeds which had not germinated after germination trials were decreased (ca. ~20%) relative to uneaten seeds that had also not germinated. Our results show that, despite the low recorded seed recovery, camels can potentially disperse seeds of P. juliflora, which is in line with field observation showing P. juliflora expansion along the camels' routes in Gebel Elba National Park, south‐east Egypt.

Peer Review #2 of "Herbivore corridors sustain genetic footprint in plant populations: a case for Spanish drove roads (v0.2)"

“…They also show to be pollinator reserves with a higher relevance than peri-urban grassland patches. Such important role played by human settlements for seed dispersal is not surprising, given that human-mediated dispersal adds to livestockmediated dispersal mechanisms (Auffret 2011;Auffret & Cousins 2013) which are problematic for the spread of invasive species (Abbas et al 2018). However, it offers insights on how an unnatural over-dispersal that facilitates invasiveness of some plant species (Wilson et al 2009) may be visible already at small geographical scales such as the one regarded in this study.…”

Herbivore corridors sustain genetic footprint in plant populations: a case for Spanish drove roads

“…A further relevant outcome of our study is the important role that human settlements seem to play for seed dispersal. The result is not surprising given that human-mediated dispersal adds to livestock-mediated dispersal mechanisms (Auffret 2011) which are problematic for the spread of invasive species (Abbas et al 2018). However, it offers insights on how an unnatural overdispersal that facilitates invasiveness of some plant species (Wilson et al 2009) may be visible already at small geographical scales such as the one regarded in this study.…”

Seed germination and early seedling survival of the invasive speciesProsopis juliflora(Fabaceae) depend on habitat and seed dispersal mode in the Caatinga dry forest

“…Prosopis juliflora as an invasive plant species benefiting from dispersal services offered by exotic animals is far from novel, with a number of examples for species of this genus ( Abbas, Mancilla-Leytón & Castillo, 2018 ). Ingestion and deposition by livestock is not required for Prosopis seeds to germinate, but it improves seed germination, seedling performance and long-distance seed dispersal of this plant as it has a patchy distribution and no native vertebrate species have been found to disperse P. juliflora seeds in the Caatinga region.…”