Integrating frugivory and animal movement: a review of the evidence and implications for scaling seed dispersal

Abstract

General principles about the consequences of seed dispersal by animals for the structure and dynamics of plant populations and communities remain elusive. This is in part because seed deposition patterns emerge from interactions between frugivore behaviour and the distribution of food resources, both of which can vary over space and time. Here we advocate a frugivore-centred, process-based, synthetic approach to seed dispersal research that integrates seed dispersal ecology and animal movement across multiple spatio-temporal scales. To guide this synthesis, we survey existing literature using paradigms from seed dispersal and animal movement. Specifically, studies are discussed with respect to five criteria: selection of focal organisms (animal or plant); measurement of animal movement; characterization of seed shadow; animal, plant and environmental factors included in the study; and scales of the study. Most studies focused on either frugivores or plants and characterized seed shadows directly by combining gut retention time with animal movement data or indirectly by conducting maternity analysis of seeds. Although organismal traits and environmental factors were often measured, they were seldom used to characterize seed shadows. Multi-scale analyses were rare, with seed shadows mostly characterized at fine spatial scales, over single fruiting seasons, and for individual dispersers. Novel animal- and seed-tracking technologies, remote environmental monitoring tools, and advances in analytical methods can enable effective implementation of a hierarchical mechanistic approach to the study of seed dispersal. This kind of mechanistic approach will provide novel insights regarding the complex interplay between the factors that modulate animal behaviour and subsequently influence seed dispersal patterns across spatial and temporal scales.

Connecting Resource Tracking by Frugivores to Temporal Variation in Seed Dispersal Networks

“…The ubiquity of resource tracking across diverse habitats is likely due to the patchiness of resources in most ecosystems, irrespective of geographical and climatic zone. However, the extent to which resources vary in space and time can be a function of geography, climate, and the scale at which resource variation is observed (Fleming, 1992;Ting et al, 2008;Garcia et al, 2011;Côrtes and Uriarte, 2013). For example, in seasonal environments, fruits and other types of food resources have periods when they are unavailable on the landscape due to more extreme climate conditions, whereas in aseasonal environments, stable conditions result in many food types being available year-round with the relative amount of this resource varies across space and time (Jordano, 1992).…”

Seed dispersal by the lek-forming white-bearded manakin (Manacus manacus, Pipridae) in the Brazilian Atlantic forest

“…How far seeds are moved from maternal plants and how they are distributed in space by dispersal agents are key topics for the understanding of the reproductive success of individual plants (Côrtes & Uriarte 2013). As a general rule, the farther from its maternal plant a seed is deposited the higher its chance of escape from mortality (Jansen et al 2008).…”

From ratites to rats: the size of fleshy fruits shapes species' distributions and continental rainforest assembly

“…Many studies have contributed to the mechanistic understanding of temporal, spatial and phylogenetic variation in seed deposition patterns based on interactions between frugivore behaviour and the distribution of food resources (reviewed in [5]). While providing important insights into local assembly processes [6], it has been difficult for these approaches to generalize more broadly and across larger scales.…”

“…Technical limitations related to tracking seed movements have constrained the interpretation of community-level dispersal patterns to a compilation of components examined individually across different scales. A more integrated picture of the role of dispersal in assembly patterns will only emerge if frugivore-mediated dispersal can be measured as part of a complex process that takes into account both temporal and spatial scales [3,5].…”