Speciation, extinction and explosions induced by sudden environmental changes

Abstract

We study the evolution of sexually reproducing populations subjected to sudden environmental changes. Using an individual based model we consider scenarios where abrupt changes can affect the carrying capacity, the mating range or the strength of assortativity, that controls the minimum similarity between individuals that allows mating to occur. We show that a boost in carrying capacity can either lead to new speciation events, thereby increasing biodiversity, or to widespread extinctions, causing the system to become dominated by a single species. A similar effect is observed with respect to the mating range. We show that the key factor determining the outcome of the process is genome length, i.e., the number of genes controlling reproduction and assortativity. We also show that when mating becomes more restrictive, increasing the degree of assortativity, a burst of speciation occurs. The explosion lasts only for a few generations, converging to values larger than before the change, but not as high as at the peak.