title: Acquired phototrophy stabilises coexistence and shapes intrinsic dynamics of an intraguild predator and its prey.
abstract: In marine ecosystems, acquired phototrophs - organisms that obtain their photosynthetic ability by hosting endosymbionts or stealing plastids from their prey - are omnipresent. Such taxa function as intraguild predators yet depend on their prey to periodically obtain chloroplasts. We present a new theory for the effects of acquired phototrophy on community dynamics by analysing a mathematical model of this predator-prey interaction and experimentally verifying its predictions with a laboratory model system. We show that acquired phototrophy stabilises coexistence, but that the nature of this coexistence exhibits a 'paradox of enrichment': as light increases, the coexistence between the acquired phototroph and its prey transitions from a stable equilibrium to boom-bust cycles whose amplitude increases with light availability. In contrast, heterotrophs and mixotrophic acquired phototrophs (that obtain < 30% of their carbon from photosynthesis) do not exhibit such cycles. This prediction matches field observations, in which only strict ( > 95% of carbon from photosynthesis) acquired phototrophs form blooms.
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
authors.forename: Holly V
authors.initials: HV
authors.lastname: Moeller
authors.affiliation: Department of Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Elina
authors.initials: E
authors.lastname: Peltomaa
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Johnson
authors.affiliation: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Neubert
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology*; D016798:Ciliophora / Q000502:physiology*; D044785:Cryptophyta / Q000502:physiology*; D017753:Ecosystem; D020387:Food Chain; D008027:Light; D008954:Models, Biological; D052817:Phototrophic Processes / Q000502:physiology*; D010839:Phytoplankton / Q000502:physiology*
keywords: Acquired metabolic potential; Mesodinium rubrum; community ecology; intraguild predation; kleptoplastidy; mixotrophy