The evolution of nomadic swarm raiders: Determining the genetic component of army ant castes

2013 REU Project:

The army ant Eciton burchellii feeds in nomadic swarms and are keystone social predators of Neotropical rainforests. Workers leave the nest in groups of up to several hundred thousand individuals to dismember live prey, exerting strong top-down effects on community structure in the leaf litter. Undoubtedly, a large part of their ecological success can be attributed to their complex caste system, featuring morphologically distinct soldiers that play a critical role in colony defense. Although it is generally held that the diet and rearing environment of developing larvae determines the physical caste of adult individuals, highly polyandrous systems have shown that caste determination might have a significant genetic component. We will use comparative morphometrics to investigate the morphological variation in individuals of different castes, and link this variation to genetic microsatellite data to understand genetic contribution to caste determination in 16 E. burchellii colonies. Considering an average E. burchellii army ant queen mates with 13 males, one of the central questions of this research will be whether certain patrilines have a greater propensity to develop into a particular caste. Furthermore, whether the morphological variation observed in certain patrilines is fundamentally different than other patrilines.

Research methods and techniques: Interns will receive training in imaging, specimen mounting, digital measurement software, geometric morphometric analysis, and multivariate statistics. Moreover, interns will learn how to analyze microsatellite data, and understand the mechanisms behind this molecular method. Depending on spring work flow, there is a possibility that the intern will also receive training in DNA extraction, PCR, and fragment analysis in the Museum’s core genetics facility, the Pritzker Laboratory and the DNA Discovery Center.

Curator/Advisors: Dr. Corrie Moreau (Assistant Curator, Zoology/Insects) and Max Winston (Ph.D. graduate student, Zoology/Insects)