The Life of a Dead Ant: The Expression of an Adaptive Extended Phenotype

Sandra B. Andersen*, Sylvia Gerritsma, Kalsum M. Yusah, David Mayntz, Nigel L. Hywel-Jones, Johan Billen, Jacobus J. Boomsma, David P. Hughes

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Specialized parasites are expected to express complex adaptations to their hosts. Manipulation of host behavior is such an adaptation. We studied the fungus Ophiocordyceps unilateralis, a locally specialized parasite of arboreal Camponotus leonardi ants. Ant-infecting Ophiocordyceps are known to make hosts bite onto vegetation before killing them. We show that this represents a fine-tuned fungal adaptation: an extended phenotype. Dead ants were found under leaves, attached by their mandibles, on the northern side of saplings similar to 25 cm above the soil, where temperature and humidity conditions were optimal for fungal growth. Experimental relocation confirmed that parasite fitness was lower outside this manipulative zone. Host resources were rapidly colonized and further secured by extensive internal structuring. Nutritional composition analysis indicated that such structuring allows the parasite to produce a large fruiting body for spore production. Our findings suggest that the osmotrophic lifestyle of fungi may have facilitated novel exploitation strategies.

Original languageEnglish
Pages (from-to)424-433
Number of pages10
JournalAmerican Naturalist
Volume174
Issue number3
DOIs
Publication statusPublished - Sep-2009

Keywords

  • carpenter ants
  • histological cross sections
  • life-history evolution
  • Ophiocordyceps
  • sclerotia
  • behavioral manipulation
  • TROPICAL FOREST ECOSYSTEMS
  • RELATIVE-HUMIDITY
  • BEHAVIOR
  • FUNGI
  • MANIPULATION
  • TEMPERATURE
  • GERMINATION
  • FORMICIDAE
  • HAIRWORMS
  • RELEASE

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