title: Temporal dynamics of seed excretion by wild ungulates: implications for plant dispersal.
abstract: Dispersal is a key process in metapopulation dynamics as it conditions species' spatial responses to gradients of abiotic and biotic conditions and triggers individual and gene flows. In the numerous plants that are dispersed through seed consumption by herbivores (endozoochory), the distance and effectiveness of dispersal is determined by the combined effects of seed retention time in the vector's digestive system, the spatial extent of its movements, and the ability of the seeds to germinate once released. Estimating these three parameters from experimental data is therefore crucial to calibrate mechanistic metacommunity models of plant-herbivore interactions. In this study, we jointly estimated the retention time and germination probability of six herbaceous plants transported by roe deer (Capreolus capreolus), red deer (Cervus elaphus), and wild boar (Sus scrofa) through feeding experiments and a Bayesian dynamic model. Retention time was longer in the nonruminant wild boar (>36 h) than in the two ruminant species (roe deer: 18-36 h, red deer: 3-36 h). In the two ruminants, but not in wild boar, small and round seeds were excreted faster than large ones. Low germination probabilities of the excreted seeds reflected the high cost imposed by endozoochory on plant survival. Trait-mediated variations in retention time and germination probability among animal and plant species may impact plant dispersal distances and interact with biotic and abiotic conditions at the release site to shape the spatial patterns of dispersed plant species.
authors.affiliation: Irstea, UR EFNO, centre de Nogent-sur-Vernisson F-45290, Nogent-sur-Vernisson, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Picard
authors.affiliation: UR BIOGER, INRA, Avenue Lucien Brétignières BP01, 78850, Thiverval-Grignon, France ; UR MIAJ, INRA, Domaine de Vilvert 78352, Jouy-en-Josas CEDEX, France ; Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, campus CNRS 1919 Route de Mende, 34293, Montpellier 5, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Papaïx
authors.affiliation: Irstea, UR EFNO, centre de Nogent-sur-Vernisson F-45290, Nogent-sur-Vernisson, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gosselin
authors.affiliation: UR CEFS, INRA BP 52627, 31326, Castanet-Tolosan, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Picot
authors.affiliation: UR CEFS, INRA BP 52627, 31326, Castanet-Tolosan, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Bideau
authors.affiliation: Irstea, UR EFNO, centre de Nogent-sur-Vernisson F-45290, Nogent-sur-Vernisson, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Baltzinger
keywords: Bayesian dynamic model; digestion mode; endozoochory; metacommunity dynamics; retention time; ruminants