  The basic mechanics of evolution have been understood since Darwin. But
debate continues over whether macroevolutionary phenomena are driven primary by
the fitness structure of genotype space or by ecological interaction. In this
paper we propose a simple, abstract model capturing some key features of
fitness-landscape and ecological models of evolution. Our model describes
evolutionary dynamics in a high-dimensional, structured genotype space with a
significant role for interspecific interaction. We find some promising
qualitative similarity with the empirical facts about macroevolution, including
broadly distributed extinction sizes and realistic exploration of the genotype
space. The abstraction of our model permits numerous interpretations and
applications beyond macroevolution, including molecular evolution and
technological innovation.
