Frugivore behaviour determines plant distribution: a spatially‐explicit analysis of a plant‐disperser interaction

Abstract

The spatial distribution of plants (and other primarily sessile organisms) depends on the interplay between their ecological requirements and the spatial template set before, during, and after the dispersal process. In the case of animal‐dispersed plants, the spatial characteristics of animal behaviour during the seed dispersal process are likely to leave a lasting imprint on plant distribution. Here, we hypothesize that the activity patterns of the frugivorous lizard Podarcis lilfordi directly influence the spatial distribution of the fleshy‐fruited shrub Daphne rodriguezii. To evaluate this hypothesis, we first analysed lizard activity, following radio‐tracked lizards during the plant's fruiting period, and identified its main determinants at several spatial scales of habitat aggregation (from 12.5 to 150 m). We hypothesised that lizard activity depends on differential habitat features explaining its territory use plus habitat preferences associated with each movement bout. In a second step, the most important determinants of lizard activity plus the variables describing habitat structure were used to predict the presence of adult and juvenile plants. Predictability of lizard activity (based on AUC and Pearson regression coefficients) was higher at broad spatial‐scales of habitat aggregation (75 m). The two best predictors of lizard activity were the habitat features of and the distance to the core area (defined as the area enclosing the 0.50 cumulative probability of lizard locations). Plant presence was best predicted by models based on a combination of lizard activity and habitat features at local spatial scales (1.5 m). Best models included habitat features and lizard activity for adult plants, and local‐scale habitat features, the proximity of adult plants and lizard activity for juveniles. In both cases, most plants (50–60%) were located at ‘optimal sites’ (both favourable for lizards and with adequate habitat features), whereas a small fraction of them (3–10%) were located at dispersal‐limited sites (i.e. with adequate habitat features but suboptimal for lizards). Our results thus suggest that the interplay between lizard activity and local habitat features determines the spatial patterns of juvenile‐plant presence and leaves a lasting signature on adult‐plant distribution.

Landscape structure shapes carnivore-mediated seed dispersal kernels

“…This spatially aggregated seed-deposition pattern is relatively common in nature, particularly when frugivores mediate dispersal processes (e.g. Rodríguez-Pérez et al 2012). In frugivorous mammals, patterns of foraging activity and scent territorial marking in relation to the local landscape structure are largely considered to generate clump-dispersal patterns (López-Bao and González-Varo 2011).…”

Predicting forest management effects on oak–rodent mutualisms

“…Collecting new data that combine tracked mice during the fruiting period and seed deposition patterns are needed to find out if wood mice use preferential seed dispersal paths in highly heterogeneous landscapes. Such data may allow us to parameterize a more realistic movement model that can create anisotropic two dimensional maps of the probability of seed dispersal (Santamaría et al , Rodriguez‐Perez et al ).…”

Divergent effects of forest edges on host distribution and seed disperser activity influence mistletoe distribution and recruitment

“…). More importantly, a previous study used an equivalent sample size of radiotracked frugivores ( n = 10 with the lizard Podarcis lilfordii , Rodríguez‐Pérez, Wiegand & Santamaria ) to obtain reliable (habitat‐based) estimates of frugivore visitation probability and frugivore‐mediated seed rain, which were validated using the distribution of adult and juvenile plants. On the other hand, the abundance of mistletoe juveniles had a more complex pattern: it increased with host availability and bamboo cover as well as adult abundance, which showed a negligible effect of the distance to the forest edge, and increased with marsupial abundance (Rodriguez‐Cabal, Aizen & Novaro ).…”

“…Secondly, we modelled the habitat preferences of each individual marsupial, taking into account solely the habitat availability within such individual's home range. For each cell included in the individual′s home‐range area, we modelled the effect of four habitat characteristics (distance to edge, canopy cover, number of trees and bamboo cover) on marsupial visitation probability (estimated as the number of relocations per cell, including a value of zero for cells with no relocation but included within the home range) (see Figure S3 and for an equivalent procedure see also Rodríguez‐Pérez, Wiegand & Santamaria ).…”

“…). Such an assumption is based on the relationship between the frequency of relocation of an individual and its abundance, which has been seen to hold true when the species is at its carrying capacity (Rodríguez‐Pérez, Wiegand & Santamaria ; Boyce et al . ).…”