Dynamic patterns of adaptive radiation<br><br>
Sergey Gavrilets and Aaron Vose<br><br>

2005 Proc.  Natl. Acad.  Sci.  USA 102: 18040-18045
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Adaptive radiation is defined as the evolution of ecological and
phenotypic diversity within a rapidly multiplying lineage. When it
occurs, adaptive radiation typically follows the colonization of a
new environment or the establishment of a "key innovation,"
which opens new ecological niches and
or new paths for evolution.
Here, we take advantage of recent developments in speciation
theory and modern computing power to build and explore a
large-scale, stochastic, spatially explicit, individual-based model of
adaptive radiation driven by adaptation to multidimensional ecological
niches. We are able to model evolutionary dynamics of
populations with hundreds of thousands of sexual diploid individuals
over a time span of 100,000 generations assuming realistic
mutation rates and allowing for genetic variation in a large number
of both selected and neutral loci. Our results provide theoretical
support and explanation for a number of empirical patterns including
"area effect," "overshooting effect," and "least action
effect," as well as for the idea of a "porous genome." Our findings
suggest that the genetic architecture of traits involved in the most
spectacular radiations might be rather simple. We show that a
great majority of speciation events are concentrated early in the
phylogeny. Our results emphasize the importance of ecological
opportunity and genetic constraints in controlling the dynamics of
adaptive radiation.