Ecological world

The Amazonian rainforest was transformed over two thousand years ago by ancient people who built hundreds of large, mysterious earthworks. Geoglyph photos. Credit: Jenny Watling Findings by Brazilian and UK experts provide new evidence for how indigenous people lived in the Amazon before European people arrived in the region. The ditched enclosures, in Acre state in the western Brazilian Amazon, were concealed for centuries by trees. Modern deforestation has allowed the discovery of more than 450 of these large geometrical geoglyphs. The function of these mysterious sites is still little understood -- they are unlikely to be villages, since archaeologists recover very few artefacts during excavation. The layout doesn't suggest they were built for defensive reasons. It is thought they were used only sporadically, perhaps as ritual gathering places. The structures are ditched enclosures that occupy roughly 13,000 km 2 . Their discovery challenges assump

B iogeography : the nature of the subject, its history and its applications  In 1994, an article in the journal New Scientist proclaimed that 'Since biogeography holds the key to the survival of life, it deserves more attention' (Bowman, 1994). That statement is a very fitting opening to this first chapter. Biogeography is about the geography of plants, animals and other or-ganisms, that is, the study of the geographical distribution of plants, animals and other organisms.  Biogeographical research helps us to understand the patterns and processes of distribution and the factors that cause and maintain those patterns and processes. The patterns of distribution that we find today amongst living organisms have been determined by many things, including the following: Evolution Physiological and behavioural adaptations Dispersal mechanisms and levels of dispersal abilities Competition between species Ecological succession Climate change Sea level changes Moving contin