Evolution

Bultman et al. (2012)
  1) What were the authors trying to investigate?
  * Neotyphodium coenophialum is an ascomycetous fungus that lives endophytically within tall fescue grass and may be important in modulating multitrophic interactions and trophic cascades due to its production of alkaloids that are toxic to some herbivores. Through the toxic alkaloids the endophyte acts as a defensive mutualist with its host grass
  * Given the trophic cascades endophytes can initiate, the effect of endophytes on the entire food web should be assessed to determint the mechanisms by which endophytes affect the interaction between grasses and insect herbivores.
  * Approach was to take advantage of the recent insertion of novel fungal isolates, collected from tall fescue in its native range, into various cultivars of forage grasses.
  * To add to understanding of fungal endophytes and multitrophic interactions, they conducted an experiment in a semi-natural setting to assess the effect of fungal isolate on multitrophic interactions involving aphid and parasitoid populations.
  2) How did they do their investigation?
  * Seeds of Jesup tall fescue trees were planted with a common fungal strain   N. coenophialum, an novel fungal isolate AR577, or uninfected in 10.2 centimeter diameter pots using LC1 soil mix. Total of 20 pots per treatment and one plant per pot. (Seeds were from New Zealnad)
  * Pots were maintained outdoors on a patio in a randomized block design of three columns with each row containing one of the three treatment types with position randomized within each row. Plants were watered to supplement natural rainfall as needed and received full sun for about 4-5 hours on cloudless days.
  * Five weeks following germination, the array was seeded with R. padi aphids, common pests of grasses by placing four pots of infested barley plants near the treatment plants for one week.
  * Source plants were infested not only with R.padi but also with aphids...