Top-down and bottom-up effects modulate species co-existence in a context of top predator restoration

Abstract

Mesopredators abundance is often limited by top-order predators and also by key food resources. However, the contribution of these bidirectional forces to structure carnivore community is still unclear. Here, we studied how the presence and absence of an apex predator which is currently recovering its former distribution range, the Iberian lynx (Lynx pardinus), determined the absolute abundance and fine-scale spatiotemporal avoidance mechanisms of two sympatric mesocarnivores (stone marten Martes foina and common genet Genetta genetta) with different dietary plasticity. We hypothesized that the lynx causes a mesopredator suppression and subordinate predators develop segregation strategies in respect to their trophic niche breadth. We placed 120 camera-traps in Southern Spain for 8 months in two consecutive years to estimate mesocarnivore abundances by using SCR Bayesian models, prey availability and assess spatio-temporal patterns. We found that the lynx reduced mesocarnivore abundance up to 10 times. Stone marten, a mesopredator with a broad food resources spectrum, showed a total spatial exclusion with the apex predator. Meanwhile, fine-scale avoidance mechanisms allowed the genet to persist in low density inside lynx territories, probably taking advantage of high availability of its preferred prey. Thus, the strength of these top-down and bottom-up effects was rather species-specific. Given the recent recovery of large carnivore populations worldwide, variation in suppression levels on different mesopredator species could modify ecosystem functions provided by the carnivore community in contrasting ways.

Modeling time-varying phytoplankton subsidy reveals at-risk species in a Chilean intertidal ecosystem

“…For herbivore species not buffered by increased bottom-up effects, our simulations imply that the boost in phytoplankton pulse size can lead to sufficient intensification of top-down, negative effects that it pushes the population over a threshold of low biomass to a point that it cannot recover. These results are consistent with experimental observations showing increased risk of extirpation in meso-predator populations due to an imbalance in top-down and bottom-up forcing 49 – 51 . For these, variation in risk to extirpation depends on network connectivity and predator identity.…”

Apex predators can structure ecosystems through trophic cascades: Linking the frugivorous behaviour and seed dispersal patterns of mesocarnivores

“…Thus, we were able to compare the seed‐dispersal patterns of mesocarnivores among predation‐risk and predation‐free scenarios. We studied the lynx distribution and abundance of mesocarnivores using camera‐trapping surveys before carrying out this study (Table S1; Burgos et al., 2023). Since mesocarnivores can alter their habitat‐use patterns under predation risk, we selected two different types of habitats in each locality which could affect the environmental conditions of the seed deposition sites and seed‐dispersal effectiveness (Schupp, 2007; Schupp et al., 2010): (a) mature forest with a dense shrub stratum and (b) open vegetation with scarce shrubs and isolated trees (see Figure 1; Figure S1).…”

Bottom‐up rather than top‐down mechanisms determine mesocarnivore interactions in Norway

“…Several large carnivore species are now recovering across large parts of Europe (Chapron et al., 2014), with potential cascading effects through the entire carnivore community. In Southern Spain, for example, the recovery of the Iberian lynx ( Lynx pardinus ) exerted a strong suppression control of two sympatric mesocarnivores (Burgos et al., 2023). However, the strength of this top‐down effect differed for different mesocarnivore species, and it was modulated by prey availability.…”