Trait evolution, biome shifts and spatiotemporal diversification in Neotropical tortoise beetles

• Applicant: Dr. Marianna Simões
• Subject Area: Systematics and Morphology (Zoology)
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541650744

Understanding the origins of convergent patterns is crucial for deciphering speciation mechanisms and environmental adaptation, especially in disparate yet ecologically neighboring landscapes, like the interconnected biomes in the Neotropics. In this region lies the "South American Dry Diagonal", which along with seasonally dry tropical forests (SDTFs) forms an expansive corridor composed of a diverse range of seasonally dry vegetation and savannas distinguished by species composition, ecology, and history. These conditions act as both a geographical and climatic barrier to species migration - aligning with the principle of biome conservatism -, and migration into these biomes is expected to lead to ecological speciation. However, the role of biome shifts and their relationship with trait evolution and how both drive lineage diversification, especially in seasonally dry vegetation biomes, remains unclear. This gap in our understanding is especially notable in herbivorous lineages, despite their ecological significance and contribution to global biodiversity. To address these questions, we use Dorynotini, a tribe of Neotropical tortoise beetles, as a model. Dorynotini, with their wide distribution across the Neotropics (South and Central America, Greater Antilles) span both humid (tropical rainforest) and seasonally dry regions (savanna, SDTFs). They showcase distinct morphotypes that align with the delineation of biomes. In this study, we will 1) generate a well-resolved phylogeny of Dorynotini using a near-complete taxon sampling and phylogenomic methods (anchored hybrid enrichment) to (2) resolve pendant taxonomic questions; (3) verify our preliminary hypothesis on convergent evolution of traits, including alignment with biome shifts, to potentially unveil associations of traits and biomes; (4) understand when, in which direction, and how often biome transitions happened to answer questions about biome conservatism and historical connectivity of biomes across the Neotropical realm; (5) understand if transitions between tropical rainforests and drier, open vegetation types (e.g. savanna, SDTFs) led to increased lineage diversification; (6) infer whether biome shifts and diversification coincide with patterns of trait evolution; and (7) elucidate the ancestral range of Dorynotini, the biogeographical processes that guided the colonization of the Greater Antilles and the spread across disjunct dry vegetation areas.

• DFG Programme: Research Grants