Can camels disperse seeds of the invasive tree Prosopis juliflora?
Prosopis juliflora (Fabaceae) is a is a tree 3-12 m tall, sometimes shrubby with spreading branches. The species is native to Mexico, Central and South America and the Caribbean and has been introduced to many regions of the world, including the EPPO region where it is present in Algeria, Spain (mainland and the Canary Islands: Gran Canaria), Israel, Jordan, Morocco, Tunisia. In the native and introduced ranges, P. juliflora is found in a number of different habitats including: wastelands, forests, managed and natural grasslands, coastal areas (including coastal dunes), wetlands, abandoned fields and urban areas (for example roadsides). In particular, in the introduced range, P. juliflora can invade rangeland, where it can form impenetrable thickets, and encroaches upon agricultural and abandoned land and can quickly invade uncultivated fields. P. juliflora was introduced intentionally into the Gebel Elba National Park in Egypt in the 1980s for agroforestry uses and has since become an invasive species. Camels have been suggested as an important dispersal mechanism for Prosopis species in this area as the spread of the species follows trade routes and animal tracks. In the current study, four camels of similar age and weight were fed 70 fruits containing approximately 1 000 seeds which were then retrieved from the camel’s dung at 24-hour intervals over 96 hours. Retrieved seeds were tested for germination and viability and compared to control seeds (seeds not eaten by camels). The passage of seeds through the camel’s gut accelerated seed germination (48 % - 75 %) compared to control seeds (15 % germination). This was mainly shown to be due to the pericarp being removed as the fruits passed through the camel. Those fruits that remained intact following passage through the gut had decreased germination (20 % lower) compared to the control.
Sources
Abbas AM, Mancilla-Leyton JM, Castillo JM (2018) Can camels disperse seeds of the invasive tree Prosopis juliflora. Weed Research 58, 221-228.