We describe an automatic web service composition framework for Phylotastic, a project aimed at developing a platform for generating phylogenetic trees. We will begin with a short description of Phylotastic. Afterwards, we present the overall architecture of our framework and describe its components such as the ontology API, the planning module, the workflow configuration module, the execution and monitoring module. We illustrate the working of our framework using a use case and discuss the desirable features of the final system.