SYSTEMATICS AND EVOLUTION OF THE LEAF-BEETLE TRIBE DORYNOTINI (COLEOPTERA: CHRYSOMELIDAE: CASSIDINAE)

Abstract

The impact of environmental gradients on morphology has been an important topic in ecology and evolutionary biology, as geographic variation in environmental conditions may be a major factor involved in diversification. As such, phenotypic gradients (clines) associated with environmental gradients are worth investigating and understanding in greater detail. The Neotropical tribe Dorynotini Monrós and Viana, 1949 is a monophyletic group of tortoise beetles distributed from central Mexico to northern Argentina. Members are morphologically characterized by possessing an elytral suture that is distinctly adorned with a tubercle or a narrow vertical spiniform post-scutrellar projection. This spine exhibits a latitudinal gradient of continuous increase in height and decrease in width towards south of the tribe’s range. This cline provides initial evidence for geographic radiation, and grounds to investigate the interaction of climatic factors associated with the geographic complexity within the clade’s distribution, which may be the potential drivers to the group’s morphological and ecological diversity. Here, I reconstruct the evolutionary history of Dorynotini and seek the mechanisms driving the morphological heterogeneity contemplated by the group. The steps towards this goal included (Chapter 1, 2, 3 and 4) complete a species-level taxonomic revision of the tribe, to allow derive decisions about species delimitation; patterns of species distribution, morphology and ecology; (Chapter 5) test the monophyly of the tribe and its genera by combining morphological and molecular data, to elucidate biogeographical patterns, and investigate the homology and evolution of the elytral post-scutellar projection and other key characters using ancestral character state reconstruction; and finally (Chapter 6), I explore the evidence behind the apparent cline by testing associations between climate and morphology across the clade’s distribution using an approach based on ecological niche modeling and morphological and environmental hypervolumes.