Abstract
A fundamental question in community ecology is the role of predator–prey interactions in food-web stability and species coexistence. Although microbial microcosms offer powerful systems to investigate it, interrogating the environment is much more arduous. Here, we show in a 1-year survey that the obligate predators Bdellovibrio and like organisms (BALOs) can regulate prey populations, possibly in a density-dependent manner, in the naturally complex, species-rich environments of wastewater treatment plants. Abundant as well as rarer prey populations are affected, leading to an oscillating predatory landscape shifting at various temporal scales in which the total population remains stable. Shifts, along with differential prey range, explain co-existence of the numerous predators through niche partitioning. We validate these sequence-based findings using single-cell sorting combined with fluorescent hybridization and community sequencing. Our approach should be applicable for deciphering community interactions in other systems.
Highlights
A fundamental question in community ecology is the role of predator–prey interactions in food-web stability and species coexistence
The data suggest that while diversity differed between the two Bdellovibrio and like organisms (BALOs) clades, these appear to be abundant
The large-scale BALO predators-targeted time series analysis performed here uncovers features of complex trophic networks linked to the activity of BALOs
Summary
A fundamental question in community ecology is the role of predator–prey interactions in food-web stability and species coexistence. A fundamental question in community ecology is the role of predator–prey interactions in trophic web stability and species coexistence. Predatory interactions have profound effects on food webs, among others by promoting diversity and creating trophic cascades that may vary in length and strength, depending on various parameters, e.g. predator size, temperature and else[1,2] Inherent properties such as the prey range of a predator, i.e. being a generalist or a specialist, or spatial complexity further strongly affect the type of control, promoting top-down or bottom-up effects[3,4,5]. BALOs are ubiquitous in soil and in water bodies and are considered to be “intermediate” versatilists, neither generalists nor specialists[9]
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