domingo, diciembre 24, 2006
Quaternary changes of Vertebrate Communities across and between continents
En el próximo VIII INQUA Congress 2007 que se va a celebrar en Cairns (Australia) del 28 de Julio al 3 de Agosto se va a celebrar una sesión temática titulada "Palaeoecology and Human Evolution". Nos han enviado información sobre este simposio que adjuntamos para los interesados en participar.
Our symposium will focus on the main aspect of mammalian fauna’s evolutionary patterns and modifications during the last 3 Ma. For the last decades, many scientists compiled database on fossil terrestrial vertebrates, especially mammals, at regional or sub-continent scale. These studies bring important insights about evolutonary processes, biochronology, or paleoecological and paleoenvironmental informations; which are sometimes connected with early hominid evolution and peopling. One of the main topics concerns the relation with Plio-Pleistocene global climate change as an important influence on evolution and faunal community change. The role played by environmental factors in large mammal changes has been interpreted in various ways: for instance following the "Stationary" model, diversity is primarily regulated by density-dependent factors in the physical environment (Rosenzweig 1975); according to the “Habitat Theory” (Vrba 1992), "Turnover Pulse Hypothesis" (Vrba 1992, 1995a), “Traffic Light model”(Vrba 1995a) and “Relay Model” (Vrba 1995a). Such theories claim changes in the physical environment (such as physical parameters and primary resources) or in the habitat drive evolutionary changes. Anyhow, changes in mammal faunal diversity over time have often been considered the result of bioevents linked to major climatic changes: physical and/or biotic environmental variations caused by climatic changes can determine concurrent bioevents in multiple lineages, affecting taxonomic diversity and changing community structure. On the other hand, some authors claimed that extrinsic environmental factors such as impacts, eruptions, and climate change have a minimal effect, and intrinsic biological factors must be more important (Prothero, 2004). Indeed, according to the "Red Queen Hypothesis", as regards macroevolution (Van Valen 1973) and microevolution (Bell 1982), changes in equilibrium may be due to the internal dynamics of competitive relationships, and do not necessarily indicate the strict interdependence of major climatic changes and evolutionary events. Equilibrium conditions can be maintained by density-dependent extinctions and originations (immigrations) and by coevolution (Van Valent 1973; Stenseth & Maynard Smith 1985: Boucot 1990).
At present times it becomes important to present and share these data in order to better i) appreciate the degree of mammal biodiversity and ii) correlate the main biotic events across and between the continental records. They would allow also considering the differences in eco-evolutive responses and defining the general common ecosystemic factors, meanwhile to envision taxonomic and biogeographical questions.
General synthesis, as a state of the art, about small and large mammal guilds for different regions of the world would be presented and discussed. The biodiversity and ecological structures of fossil vertebrate communities, their dynamic through time, would be compared. They could bring relevant points about faunal dispersal and exchange during the Quaternary Times, especially between the large mainland biomes, including specific cases such islands. They would provide reliable informations about Holocene biodiversity. Finally, a main underlying goal would be to a better temporal definition of the Quaternary period, with first and second order limits or biochronological boundaries.
Please, let us know in you are interesting in our symposium until the 15 January 2007 filling the form in attachment and e-mailing or posting it to the conveners (J-P Brugal; M.R. Palombo). Details will be presented in the second announcement that will be sent directly to those people who have registered. You will find complementary information about the XVII INQUA Congress 2007 at http://www.inqua2007.net.au/ All abstracts have to be submitted by 31 January 2007. Submission will be electronic, via this website, and will be accessible from July 2006. Abstracts will be published as an issue of Quaternary International and will be distributed to delegates at the Congress.