Niche Conservatism: A Population Dynamic Perspective

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9528602 Holt As the tide of environmental change rises inexorably around us, it is becoming increasingly urgent to understand the capacity of species to respond. An inspection of the fossil record suggests that species vary widely in their abilities to adapt to changed circumstances. Some species seem to adapt very readily to change, whereas others are quite conservative in their basic "ecological niches" (i.e., the environmental conditions in which populations of a species can persist without repeated immigration or introductions of new individuals from external sources). The aim of this research project is to develop a conceptual framework for interpreting both conservatism and rapid change in species' niches, combining a contemporary understanding of genetic change in populations with an understanding of the determinants of change in population size. The basic approach taken is to use mathematical and computer analyses which combine ecology (controls on population size) and genetics (controls on the genetic makeup of populations) to examine how species respond both genetically and numerically to different kinds of variation in their environments. For example, climate change can lead to either an altered environment across the entire range of a species, or possibly just part of its range, in a short period of time. We thus consider a range of scenarios that incorporate both environmental change in time and variations across geographic locations. Findings from this research will address significant fundamental problems in biology--why some species adapt readily and others more slowly (or not at all) in the face of environmental change. The research has implications for important applied problems, such as the design of conservation plans and understanding genetic responses of pest organisms to control programs.