Day 4

The tiredness continues. Today’s two tasks were to test our four hypotheses related to Cecropia herbivory defense and explore ant nests of different ages.

The Cecropia tree is normally in symbiosis with several species of ant. Their function is to be a defense mechanism against any threat to the integrity of the tree. This mostly means herbivory from various types of organism. However, there is a period when the tree is young prior to the colonization event of the ant population. We explored different ways in which the tree could potentially protect itself in this vulnerable period. After discussing the issue as a group for a while, covering many different possible solutions, we settled on four distinct hypotheses. Briefly, they focused on mimicry, chemical defense, leaf quality, and the predator/herbivore satiation hypothesis.

In long form these were our ideas. Maybe the young Cecropia trees are in some way similar to another species that has it’s own process for herbivory deterrence. Through mimicry, young Cecropia may benefit from the association made by herbivores. Secondly, there could be a chemical defense mechanism that is then replaced by the ants later in life. Thirdly, leaves on juveniles could be of poorer quality so as to deter herbivores, who would be better off selecting other species. Lastly (and the hypothesis I worked on), was herbivore satiation hypothesis. Under this assumption, we would expect to see high numbers of seed and juveniles, with the high number of individuals “flooding the market” and ensuring both sufficient herbivory and a proportion of individuals surviving into maturity (and therefore protection via ants).

After collecting and analyzing our data, we moved on to the ant colony structure. Scott showed us the different stages of nest. We spent the rest of the day looking for the fungus chamber and evading the (amazingly strong) bites of soldier ants.

Tomorrow, we go caving. I’m excited, as I have never done anything of the sort before.

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