Experimental evaluation of the viability in the Juniperus deppeana
forest seed dispersal by endozoochory and diploendozoochory after wild
zoo mammals' ingestion.
Abstract
Carnivores participate in forest disturbance recovery by dispersing the
seeds that pass through their digestive systems. The objective of this
study was to evaluate the capacity of mammals for Juniperus deppeana
seed dispersal with an experimental evaluation of endozoochory and
diploendozoochory, through indices of recovery, viability, changes in
testas, and retention of seeds in the digestive tract. Juniperus
deppeana fruits were collected in the Sierra Fría Natural Protected
Area, Aguascalientes, Mexico, and were administered in the diet of gray
fox (Urocyon cinereoargenteus), coati (Nasua narica) and domestic
rabbits (Oryctolagus cuniculus) these three mammals represented the
endozoochory. For the diploendozoochory, seeds excreted by rabbits were
incorporated into the diets of bobcat (Lynx rufus) and cougar (Puma
concolor) in a local zoo. The seeds present in the scats were collected,
and recovery rates and retention times were estimated; viability was
estimated by X-ray optical densitometry, and testa thicknesses and
surfaces were checked by scanning electron microscopy. The results
showed a recovery of seeds greater than 70% in all the animals; the
retention time was < 24 h in the endozoochory, but the time
was longer (24-96 h) in the diploendozoochory (P < 0.05). Seed
viability (x ̵̅ ± SD) was decreased in rabbits (74.0 ± 11.5 %) compared
to fruits obtained directly from the canopy (89.7 ± 2.0 %), while gray
fox, coati, bobcat and puma did not affect viability (P <
0.05). An increase in the thickness of the testas was also observed in
seeds excreted from all mammals (P < 0.05). Through
evaluation, our results suggest that mammalian endozoochory and
diploendozoochory contribute to dispersal of J. deppeana by maintaining
viable seeds with adaptive characteristics in the testa to promote
resilience and forest restoration. In particular, felines (predators)
can provide an ecosystem service through scarification and seed
dispersal.