RESUMO
The remarkably diverse plant communities of the Neotropics are the result of diversification driven by multiple biotic (for example, speciation, extinction and dispersal) and abiotic (for example, climatic and tectonic) processes. However, in the absence of a well-preserved, thoroughly sampled and critically assessed fossil record, the associated processes of dispersal and extinction are poorly understood. We report an exceptional case study documenting patterns of extinction in the grape family (Vitaceae Juss.) on the basis of fossil seeds discovered in four Neotropical palaeofloras dated between 60 and 19 Ma. These include a new species that provides the earliest evidence of Vitaceae in the Western Hemisphere. Eight additional species reveal the former presence of major clades of the family that are currently absent from the Neotropics and elucidate previously unknown dispersal events. Our results indicate that regional extinction and dispersal have substantially impacted the evolutionary history of Vitaceae in the Neotropics. They also suggest that while the Neotropics have been dynamic centres of diversification through the Cenozoic, extant Neotropical botanical diversity has also been shaped by extensive extinction over the past 66 million years.
Assuntos
Extinção Biológica , Fósseis , Sementes , Dispersão de Sementes , América do Sul , Evolução Biológica , Biodiversidade , FilogeniaRESUMO
Biogeographic disjunction patterns, where multiple taxa are shared between isolated geographic areas, represent excellent systems for investigating the historical assembly of modern biotas and fundamental biological processes such as speciation, diversification, niche evolution, and evolutionary responses to climate change. Studies on plant genera disjunct across the northern hemisphere, particularly between eastern North America (ENA) and eastern Asia (EAS), have yielded tremendous insight on the geologic history and assembly of rich temperate floras. However, one of the most prevalent disjunction patterns involving ENA forests has been largely overlooked: that of taxa disjunct between ENA and cloud forests of Mesoamerica (MAM), with examples including Acer saccharum, Liquidambar styraciflua, Cercis canadensis, Fagus grandifolia, and Epifagus virginiana. Despite the remarkable nature of this disjunction pattern, which has been recognized for over 75 years, there have been few recent efforts to empirically examine its evolutionary and ecological origins. Here I synthesize previous systematic, paleobotanical, phylogenetic, and phylogeographic studies to establish what is known about this disjunction pattern to provide a roadmap for future research. I argue that this disjunction pattern, and the evolution and fossil record of the Mexican flora more broadly, represents a key missing piece in the broader puzzle of northern hemisphere biogeography. I also suggest that the ENA-MAM disjunction represents an excellent system for examining fundamental questions about how traits and life history strategies mediate plant evolutionary responses to climate change and for predicting how broadleaf temperate forests will respond to the ongoing climatic pressures of the Anthropocene.
Assuntos
Plantas , Filogenia , Filogeografia , Ásia Oriental , MéxicoRESUMO
El género Oecopetalum Greenm. & C.H. Thomps. (Metteniusaceae) se distribuye en el sureste de México y en América Central (Guatemala, Nicaragua y Costa Rica). Tres especies han sido descritas. Estudiamos especímenes de herbario de Oecopetalum y realizamos un análisis filogenético basado en los genes de los cloroplastos matK y ndhF para responder a las preguntas principales: ¿Cuántas especies hay en el género Oecopetalum? ¿Es Oecopetalum monofilético? ¿Cuáles son las relaciones genéricas con otros miembros de la familia? Oecopetalum es un género monofilético con solo dos especies y Pittosporosis es el grupo hermano. La relación transatlántica de Oecopetalum y Pittosporosis es un patrón geográfico recurrente en la familia Mettenuisaceae, así como en Icacinaceae. Nuestros resultados, en concordancia con la evidencia fósil y las relaciones de otros grupos, apoyan el modelo boreotropical de migraciones terrestres de táxones tropicales desde latitudes altas durante el Paleoceno-Eoceno, globalmente cálido.
Oecopetalum Greenm. & C.H. Thomps. (Metteniusaceae) is distributed in the southeastern portion of Mexico to Central America (Guatemala, Nicaragua, and Costa Rica). Three species have been described. We studied herbarium specimens of the genus Oecopetalum and performed a phylogenetic analysis based on the plastid genes matK and ndhF to answer several major questions: How many species are in the genus Oecopetalum? Is Oecopetalum monophyletic, and how is the genus related to other members of the family? Our results indicate that Oecopetalum is monophyletic, with only two species, and sister to the Asian genus Pittosporopsis. The Trans-Atlantic relationship of Oecopetalum and Pittosporosis is a recurrent geographic pattern in the families Mettenuisaceae and Icacinaceae. Our results, in agreement the fossil record and previous phylogenetic studies, support the boreotropical model of high-latitude terrestrial migrations of tropical taxa during the globally warm Paleocene-Eocene.