Endozoochory by native and exotic herbivores in dry areas: consequences for germination and survival ofProsopisseeds

Abstract

AbstractMammalian herbivores can play a role in the endozoochorous dispersal ofProsopisseeds in the arid zones of Argentina, and the introduction of exotic mammals can change relevant parameters of the plant's reproductive ecology. Our specific goals were to quantify the seeds ofProsopis flexuosa,P. chilensisandP. torquatacontained in the faeces of native [mara (Dolichotis patagonum), guanaco (Lama guanicoe)] and exotic [donkey (Equus asinus) and hare (Lepus europaeus)] mammals, and to determine the mortality, germination percentage and germination speed of seeds borne in faeces, compared with those collected from trees. In 2006, seeds were collected directly from trees or removed from mammal faeces. Seeds were counted and classified as apparently healthy or damaged.P. torquataandP. flexuosaseeds were found in the dung of guanaco, hare and mara, whereas onlyP. flexuosaseeds appeared in donkey faeces.P. chilensisseeds were only found in guanaco faeces. There was a notable relative abundance of seeds contained in small herbivore faeces in comparison to the large herbivores. The passage through the digestive tract of animals modified seed germination capacity and speed, with great variability between animal species. Guanacos had greater effects than donkeys on mortality, germination percentage and germination speed. Differences between the effects of both smaller-sized herbivores on seeds were much smaller.