Epizoochorous dispersal by ungulates depends on fur, grooming and social interactions

Abstract

The transport phase of the animal‐mediated plant dispersal process is critical to dispersal effectiveness as it determines the spatial distribution of the diaspores released and their chance for further recruitment. Assessing this specific phase of the dispersal process generally requires combining diaspore retention times with the associated distances covered. Here, we specifically tested the effect of grooming behavior, interindividual contacts and ungulate fur on diaspore retention times and associated dispersal distances for the hooked diaspores of Xanthium strumarium L. experimentally attached to tamed individuals of three ungulate species. We used a comparative approach based on differing fur quality on different body zones of these three ungulates. During 6‐hr sessions, we monitored for grooming and social interactions that may induce intended or inadvertent diaspore detachment. Additionally, we proposed innovative approaches to directly assessing diaspore dispersal distances by red deer in situ. Fat‐tailed functions fitted diaspore retention time, highlighting the potential for long‐distance dispersal events. The longer the hair, the higher the retention capacity of diaspores in the animal's fur. As predicted, donkey retained diaspores longer than red deer and dwarf goat; and we also confirmed that diaspores attached to the short hair of the head fell off more quickly than did those on the other body zones. Dwarf goat groomed more often than both red deer and donkey, but also when it carried diaspores. Up to 14% of the diaspores detached from animal fur after specific grooming behavior. We observed, in controlled conditions, for the first time and for each ungulate species, interindividual transfers of diaspores, representing 5% of the diaspores attached to animals’ fur. Our results militate for incorporating animal behavior into plant dispersal modeling approaches.

Plants on the Move: Hitch-Hiking With Ungulates Distributes Diaspores Across Landscapes

“…They include two specific processes: regurgitation, or partial endozoochory (where diaspores are ingested and regurgitated, Prasad et al, 2006), and full endozoochory (where diaspores are ingested and defecated). External mechanisms (right shaded side of Figure 1), where diaspores are carried on the outside of the vectors on various body parts, include primary fur-epizoochory (direct adhesion to fur essentially) and secondary epizoochorous processes: transfer through contact with a conspecific (Liehrmann et al, 2018) and diaspore-laden mud adhering to hooves (Schulze et al, 2014) or the body . We have used a model ungulate to depict primary and secondary dispersal mechanisms of diaspores from a parent plant present in its home range (Figure 1).…”

“…Here diaspores become attached to the fur of passing ungulates. Diaspores carried in the fur of ungulates generally present a high turn-over-most of them will fall off during the first few hours (Bullock et al, 2011) -though attachment time does depend on the characteristics of the fur (e.g., hair curliness, hair length, Liehrmann et al, 2018). Diaspores can drop accidentally or the animals can detach them during specific grooming sessions with teeth, by scratching or by rubbing against tree trunks (Heinken et al, 2006).…”

“…Allo-grooming events or games between conspecifics in social ungulates can also lead to secondary external dispersal (described by scenario Ex2a, Figure 1). Liehrmann et al (2018) have recently documented this mechanism, called transferepizoochory for dwarf goats, Poitou donkeys and red deer hinds. Diaspore transfers might occur more frequently during the reproduction period and while rearing young.…”

Can plant traits predict seed dispersal probability via red deer guts, fur, and hooves?

“…Vector behavior will affect both diaspore attachment, for example, through selective foraging, and through grooming behavior, as was shown by Liehrmann et al (2018). The first point is especially true for an intermediate mixed feeder, such as red deer (Baltzinger et al, 2019;Karimi et al, 2018;Picard et al, 2016).…”

“…The probability for plant species to have diaspores transported through red deer intestines, fur, and/or hooves is probably dependent on (a) plant species abundance in the landscape (Bruun & Poschlod, 2006;Karimi, Hemami, Tarkesh Esfahani, Akhani, & Baltzinger, 2018;Picard et al, 2016), (b) whole-plant traits, such as diaspore number per ramet and diaspore release height (Albert, Auffret, et al, 2015;Albert, Mårell, Picard, & Baltzinger, 2015), and (c) diaspore traits, such as presence of specific appendages promoting attachment (Lepková, Horčičková, & Vojta, 2018). Behavior, including feeding preferences, is also likely to affect deer-plant interactions (Liehrmann et al, 2018). Thus, focussing on groups of plant species sharing certain traits, rather than on individual species, may reach a higher level of generalization.…”