Angelly Vasquez

McGill University
Origin of worker-caste polymorphism in fungus-farming ants

Angelly Vasquez, William Wcislo, Owen Mcmillan, Ehab Abouheif

The origin of polymorphic worker castes represents one of the major evolutionary events in ants. Generally, caste polymorphism is recognized primarily by the differences in morphology couple with a marked division of labor. Polymorphism in worker caste can be identified by a disproportional scaling between head and body size, this changes in allometry are an informative aspect of organism’s biology, in insect’s development, body scaling can represent competition for resources or developmental and genetic switch points during larvae development. In the context of worker caste, allometry determinate developmental transitions that affect the head growth with an increasing body size, resulting in different morphs in a single colony. I am working with the most complex societies of ants, the farming-fungus ants of the tribe: Attine, I have selected species of leaf-cutter ants and its sister group to elucidate the determination of worker caste in this group. In this work, I will present the first approximation to the allometry of leaf-cutter ants, I have established the allometry regression line of body length and head width using current techniques in order to find their allometric relationships. The preliminary results show a monophasic allometry for Acromyrmex echinator, Acromyrmex Coronatus a triphasic allometry for Atta cephalotes, while for their sister group a non-leaf cutter species Trachymyrmex cornetzi the allometry classification is still unclear. This preliminary results represent a remarkable knowledge of the scaling relationship in this group and provide the first insights on understanding the regulation of body scaling in complex eusocial insects.