Human‐induced reduction in mammalian movements impacts seed dispersal in the tropics

Abstract

Seed dispersal is a key process affecting the structure, composition and spatial dynamics of plant populations. Numerous plant species in the tropics rely upon animals to disperse their seeds. Humans have altered mammalian movements, which will likely affect seed dispersal distances (SDD). Altered SDD may have a range of consequences for plant communities including reduced seedling recruitment and plant biomass, seed trait homogenization, altered gene flow and a reduced capacity to respond to environmental changes. Therefore, modelling the consequences of altered animal behaviour on ecosystem processes is important for predicting how ecosystems will respond to human impacts. While previous research has focused on the link between animal species extirpation and SDD, it remains unclear how changes in mammalian movement will impact SDD. Here we implemented a mechanistic modelling approach to examine how mammalian movement reductions impact SDD in the tropics. We combined allometric theory with a mechanistic seed dispersal model to estimate SDD via the movement of 37 large frugivorous mammals (> 10 kg) in the tropics under different levels of human footprint, a global proxy of direct and indirect human disturbances. Our results suggest that assemblage-level SDD reductions are estimated to be up to 80% across the tropics in response to human disturbance. This is particularly the case in areas with high human impact such as agricultural landscapes and suburban areas. The region with the largest reductions in SDD was the Asia-Pacific with average reductions of 25%, followed by Central-South America (16%) and then Africa (15%). Our study provides insights into how human-induced changes in movement behaviour of large mammals could translate into altered ecosystem functioning.

Movement ecology of vulnerable lowland tapirs between areas of varying human disturbance

“…Problematically, human development has reduced the amount of habitat available to wildlife [ 8 , 13 , 32 ]. This has spurred substantial changes in animal movement behaviour across the globe [ 16 , 19 , 71 ], with potential consequences including reduced fitness and survival, altered predator–prey dynamics, reduced seed dispersal, genetic isolation and local extinction [ 14 , 15 , 19 , 72 ].…”

Behavioral “bycatch” from camera trap surveys yields insights on prey responses to human‐mediated predation risk

“…For example, species may shift their diel activity pattern to avoid interaction with humans, with potential consequences for resource acquisition (Gaynor et al, 2018 ; Shamoon et al, 2018 ). Ultimately, human‐induced changes in key behaviors, such as movement, can affect ecosystem services (Tucker et al, 2021 ) and serve as an early warning of impending demographic effects (Middleton et al, 2013 ). Understanding the indirect impacts of human disturbances on animal behavior is critical for developing a fuller picture of wildlife responses to anthropogenic change, and ultimately for developing effective management actions.…”

Drivers of Ecological and Evolutionary Disruptions in the Seed Dispersal Process: Research Trends and Biases

“…Multiple drivers of global change have been documented to cause pervasive disruptions in the seed dispersal process (SDD, hereafter), with poorly understood consequences for the functioning of communities and ecosystems. In the case of animal seed dispersal, plants are susceptible to dispersal failure when the animal populations on which they depend decline or even become extinct (Traveset and Richardson, 2006;Traveset et al, 2012;Pérez-Méndez et al, 2016;Rogers et al, 2017;Tucker et al, 2021). Habitat loss, land use change, overhunting, and invasive species are key threats underlying animal seed disperser population declines, extinctions, and range reductions (McConkey et al, 2012;Dirzo et al, 2014).…”