Challenges to understanding dynamics of biodiversity in time and space

The negative consequences of anthropogenic activities such as agriculture and urbanization (e.g., deforestation, greenhouse gas emissions, and pollution) have become exacerbated by rapid rates of human population increase (see Pimm et al. 2001). Subsequent habitat loss and modification has accelerated rates of extinction, creating a biodiversity crises which arguably is one of the most pressing problems of the twenty-first century. Although causative agents are unclear, the fossil record suggests that biotas undergo periods of massive extinction as well as considerable diversification (Alroy et al. 2001; Jackson and Johnson 2001) at the global scale, even in the absence of human activities. As such, quantifying the spatial and temporal dynamics of biodiversity in past and contemporary times, and understanding their mechanistic bases represent disciplinary emphases of evolutionary and environmental biology. Equally important, such understanding is a critical step in informing regional as well as global management strategies and conservation efforts. Nonetheless, considerable controversy or uncertainty exists surrounding the patterns, underlying mechanisms, and strategies of conservation (Willig 2000; Andelman and Willig 2002). The past may provide important insights into a number of relevant issues regarding contemporary biodiversity (and vice versa), but only recently has the dialogue between neontologists and paleontologists charted productive areas of collaboration. Indeed, a growing body of work has questioned the meaning of global measures of biodiversity (past or present) and has suggested that only detailed studies at local sites provide resolution to important issues about biodiversity. This is due, in part, to considerable sampling problems associated with broad-scale estimation, including the averaging of local and regional patterns.