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Abstract The soil amoeba Dictyostelium discoideum acts as both a predator and potential host for diverse bacteria. We tested fifteen Pseudomonas strains that were isolated from transiently infected wild D. discoideum for ability to escape predation and infect D. discoideum fruiting bodies. Three predation-resistant strains frequently caused extracellular infections of fruiting bodies but were not found within spores. Furthermore, infection by one of these species induces secondary infections and suppresses predation of otherwise edible bacteria. Another strain can persist inside of amoebae after being phagocytosed but is rarely taken up. We sequenced isolate genomes and discovered that predation-resistant isolates are not monophyletic. Many Pseudomonas isolates encode secretion systems and toxins known to improve resistance to phagocytosis in other species, as well as diverse secondary metabolite biosynthetic gene clusters that may contribute to predation resistance. However, the distribution of these genes alone cannot explain why some strains are edible and others are not. Each lineage may employ a unique mechanism for resistance.
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Behavioural differences underlie toxicity and predation variation in blooms of Prymnesium parvum
Abstract Much of the evolutionary ecology of toxic algal blooms (TABs) remains unclear, including the role of algal toxins in the adaptive ‘strategies’ of TAB‐forming species. Most eukaryotic TABs are caused by mixotrophs that augment autotrophy with organic nutrient sources, including competing algae (intraguild predation). We leverage the standing diversity of TABs formed by the toxic, invasive mixotrophPrymnesium parvumto identify cell‐level behaviours involved in toxin‐assisted predation using direct observations as well as comparisons between genetically distinct low‐ and high‐toxicity isolates. Our results suggest thatP. parvumtoxins are primarily delivered at close range and promote subsequent prey capture/consumption. Surprisingly, we findoppositechemotactic preferences for organic (prey‐derived) and inorganic nutrients between differentially toxic isolates, respectively, suggesting behavioural integration of toxicity and phagotrophy. Variation in toxicity may, therefore, reflect broader phenotypic integration of key traits that ultimately contribute to the remarkable flexibility, diversity, and success of invasive populations.
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- Award ID(s):
- 1831493
- PAR ID:
- 10410031
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 26
- Issue:
- 5
- ISSN:
- 1461-023X
- Page Range / eLocation ID:
- p. 677-691
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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