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

Abstract

Mammalian herbivores can play a role in the endozoochorous dispersal of Prosopis seeds 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 of Prosopis flexuosa, P. chilensis and P. torquata contained 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. torquata and P. flexuosa seeds were found in the dung of guanaco, hare and mara, whereas only P. flexuosa seeds appeared in donkey faeces. P. chilensis seeds 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.

Effect of gut passage and dung on seed germination and seedling growth: donkeys and a multipurpose mesquite from a Mexican inter-tropical desert

“…Obs). These observations contrast to those reported for P. flexuosa in which 54% of the seeds found in donkey dung were enclosed inside their endocarps (Campos et al, 2008). The opening of endocarps can allow water uptake and gas exchange stimulating germination, in comparison to closed endocarps, although it is necessary to confirm these ideas.…”

“…(3) The percentage of damaged seeds following passage through the digestive tract is relatively low (28% AE 6%; unpublished data). This percentage of damage is lower than the percentage reported for seeds of P. laevigata and P. flexuosa ingested by goats (97% ;Cantú 1990) and donkeys (45%; Campos et al 2008), respectively. This percentage is also lower than the percentage of P. laevigata seeds damaged by bruchids in the region (50%-80%; unpublished data).…”

Relaciones tróficas entre mamíferos herbívoros nativos y exóticos del Parque Provincial Ischigualasto (San Juan, Argentina)

“…Por otro lado, tanto los herbívoros nativos como los exóticos están cumpliendo roles ecológicos clave en la dispersión de semillas de algarrobo (Prosopis spp.) (Campos et al 2008(Campos et al , 2016. Sin embargo, se propone el monitoreo continuo de las poblaciones para detectar cualquier cambio que pudiera afectar de alguna manera a las especies nativas protegidas en el PPI.…”

The fencing paradigm in woodland conservation: consequences for recruitment of a semi‐arid tree

“…The main dispersers of seeds of P. flexuosa are native and exotic mammals, such as Patagonian hares ( Dolichotis patagonum ), grey foxes ( Pseudalopex griseus ), guanacos ( Lama guanicoe ), wild boars ( Sus scrofa ), cattle and horses (Campos & Ojeda ; Campos et al. ). Birds, small rodents, reptiles and ants also feed on Prosopis fruits and are potential, but probably minor, agents of dispersal compared to large herbivores.…”

“…; Campos et al. ), are likely to have been present in Ñacuñán in the past (Ojeda et al. ) but are now locally extinct.…”