Abstract
AbstractPredators can directly or indirectly shape food webs through a combination of consumptive and non‐consumptive effects. Yet, how these effects vary across natural populations and their consequences for adjacent ecosystems remains poorly resolved. We examined links between terrestrial predators and aquatic ecosystems through their effects on a locally abundant amphibian, the red‐eyed treefrog (Agalychnis callidryas), which has arboreal eggs (heavily predated by snakes and wasps) and aquatic larvae; embryos can escape terrestrial threats by hatching at an earlier age and smaller size. Our multi‐site field survey indicates that in natural populations, the relative contributions of these consumptive and non‐consumptive effects of predators can be substantial and remarkably similar. However, in mesocosms where we experimentally mimicked these predator effects, changes in the density and initial hatching age of tadpoles carried distinct consequences for aquatic food webs. Density‐dependent growth resulted in peak tadpole biomass at intermediate densities (reflecting intermediate predation), and early‐hatched tadpoles grew 16% faster and produced 26% more biomass than their late‐hatched counterparts. These changes in tadpole growth and size differentially affected zooplankton communities, and the production and stability of phytoplankton. Together, these results illustrate multiple pathways through which predators in one ecosystem can modulate the structure of adjacent food webs.
Highlights
Predators can substantially alter prey populations through a combination of changes to the abundance, behavior, morphology, or life history of their prey (Paine 1969, Carpenter and Kitchell 1993, Estes et al 2011, Costa and Vonesh 2013b)
Predators attacked ~74% of all the clutches surveyed (Fig. 2A), and in these clutches, predators reduced the proportion of embryos surviving to the tadpole stage by ~63%
Terrestrial predators reduced the proportion of hatchlings entering ponds by approximately 50%, and these reductions varied considerably across ponds from 21% to 78%
Summary
Predators can substantially alter prey populations through a combination of changes to the abundance, behavior, morphology, or life history of their prey (Paine 1969, Carpenter and Kitchell 1993, Estes et al 2011, Costa and Vonesh 2013b). Predator–prey interactions often cascade beyond the prey population to shape ecological communities, when the prey is abundant or shifts habitats during their life cycles (Knight et al 2005, Orrock et al 2010, Breviglieri et al 2017) Such cross-ecosystem linkages represent a pervasive yet understudied component of food webs (Polis et al 1997, Nakano and Murakami 2001, Breviglieri et al 2017). Predators can induce tadpoles to hatch early and enter ponds at an earlier age and smaller body size In both cases, the changes in the density or traits of tadpoles, which are key herbivores in Neotropical ponds, could have cascading effects on tadpole growth and development (e.g., via density-dependent and compensatory growth), zooplankton communities (via competition for algal resources), litter decomposition, and primary production, though the net outcomes of these interactions are difficult to predict a priori.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
