Informe de investigación
Integrating genetic, functional and comparative approaches to understanding the history of adaptations to a novel environment: When and how did frogs colonize the coastal dry forest of Colombia?
Registro en:
Colciencias
Repositorio Colciencias
Autor
Jackson Crawford, Andrew
Resumen
Amphibians are thought to be individually sensitive to environmental conditions and evolutionary conservative in their abiotic niches over deep time, yet in Colombia we observe apparently closely related populations and species surviving in diverse habitats. The seasonally dry tropical forest (SDTF) of Colombia's Caribbean coast represents a unique yet endangered biome. Given its long dry season, the tropical animals and plants of this region must survive and reproduce under harsh conditions quite distinct from the neighboring environments of the wet biogeographic Chocó and the Andes mountains. The SDTF biome is thought to be no older than the Late Eocene, created by a steady decline in global temperature and humidity. Given its geographic isolation and relatively young age, we seek to understand the temporal and biogeographic origins of the SDTF fauna and elucidate potential adaptations that have allowed animals to survive in this relatively novel environment. The long dry season should be especially demanding on the frog fauna, since these animals are particularly susceptible to desiccation at all life stages. This proposal seeks to answer the following evolutionary questions. 1) What are the relative contributions of in situ diversification within the SDTF versus vicariance due to the rise of the Eastern Cordillera or colonization from neighboring biomes? 2) In the case of colonization, which neighboring biomes represent the ancestral areas of these lineages? 3) How old is the frog fauna of the SDTF? 4) What morphological, physiological or life-history adaptations have permitted these frogs to survive the marked seasonality of the SDTF? To address these questions we propose to integrate three approaches. First, we will combine genetic analyses of within-species diversity, i.e., a phylogeographic perspective, with morphological and bioacoustic data to clarify species boundaries in our focal taxa and estimate genetic connectivity among populations. Second, we will combine new genetic data with published molecular phylogenies to place frogs of the SDTF in larger historical context, and then use comparative approaches to study ancestral areas. Third, though extensive field and museum work we will collect comparative data on traits that we hypothesize could be involved in adaptation to the long dry season of the SDTF, and again use comparative approaches to study their evolution. Thus, the diverse environments of Colombia offer a unique opportunity to study the historical and adaptive processes driving the assembly of a novel community. Understanding the evolution of adaptations to extreme climates will also increase our ability to predict the response of amphibians to global climate change.