Liliana Katinas

Eocene Patagonia Fossils of the Daisy Family

Fossil evidence suggests that daisies and sunflowers may have originated in South America more than 47 million years ago. Fossil capitula and pollen grains of Asteraceae from the Eocene of Patagonia, southern Argentina, exhibit morphological features recognized today in taxa, such as Mutisioideae and Carduoideae, that are phylogenetically close to the root of the asteracean tree. This fossil supports the hypothesis of a South American origin of Asteraceae and an Eocene age of divergence and suggests that an ancestral stock of Asteraceae may have formed part of a geoflora developed in southern Gondwana before the establishment of effective dispersal barriers within this landmass.

An extinct Eocene taxon of the daisy family (Asteraceae): evolutionary, ecological and biogeographical implications

BACKGROUND AND AIMS Morphological, molecular and biogeographical information bearing on early evolution of the sunflower alliance of families suggests that the clade containing the extant daisy family (Asteraceae) differentiated in South America during the Eocene, although palaeontological studies on this continent failed to reveal conclusive support for this hypothesis. Here we describe in detail Raiguenrayun cura gen. & sp. nov., an exceptionally well preserved capitulescence of Asteraceae recovered from Eocene deposits of northwestern Patagonia, Argentina. METHODS The fossil was collected from the 47·5 million-year-old Huitrera Formation at the Estancia Don Hipólito locality, Río Negro Province, Argentina. KEY RESULTS The arrangement of the capitula in a cymose capitulescence, the many-flowered capitula with multiseriate-imbricate involucral bracts and the pappus-like structures indicate a close morphological relationship with Asteraceae. Raiguenrayun cura and the associated pollen Mutisiapollis telleriae do not match exactly any living member of the family, and clearly represent extinct taxa. They share a mosaic of morphological features today recognized in taxa phylogenetically close to the root of Asteraceae, such as Stifftieae, Wunderlichioideae and Gochnatieae (Mutisioideae sensu lato) and Dicomeae and Oldenburgieae (Carduoideae), today endemic to or mainly distributed in South America and Africa, respectively. CONCLUSIONS This is the first fossil genus of Asteraceae based on an outstandingly preserved capitulescence that might represent the ancestor of Mutisioideae-Carduoideae. It might have evolved in southern South America some time during the early Palaeogene and subsequently entered Africa, before the biogeographical isolation of these continents became much more pronounced. The new fossil represents the first reliable point for calibration, favouring an earlier date to the split between Barnadesioideae and the rest of Asteraceae than previously thought, which can be traced back at least 47·5 million years. This is the oldest well dated member of Asteraceae and perhaps the earliest indirect evidence for bird pollination in the family.

Agriculture Biogeography: An emerging discipline in search of a conceptual framework

The challenge of increasing food production to keep pace with demand, while retaining the essential ecological integrity of production systems, requires coordinated action among science disciplines. Thus, 21st-century Agriculture should incorporate disciplines related to natural resources, environmental science, and life sciences. Biogeography, as one of those disciplines, provides a unique contribution because it can generate research ideas and methods that can be used to ameliorate this challenge, with the concept of relative space providing the conceptual and analytical framework within which data can be integrated, related, and structured into a whole. A new branch of Biogeography, Agriculture Biogeography, is proposed here and defined as the application of the principles, theories, and analyses of Biogeography to agricultural systems, including all human activities related to breeding or cultivation, mostly to provide goods and services. It not only encompasses the problem that land use seems scarcely to be compatible with biodiversity conservation, but also a substantial body of theory and analysis involving subjects not strictly related to conservation. Our aim is to define the field and scope of Agriculture Biogeography, set the foundations of a conceptual framework of the discipline, and present some subjects related to Agriculture Biogeography. We present, in summary form, a concept map which summarizes the relationship between agriculture systems and Biogeography, and delineates the current engagement between Agriculture and Biogeography through the discussion of some perspectives from Biogeography and from the agriculture research.