This site is a supplement to the article: Modelling the Evolution of Spatially Distributed Populations in the Uniformly Changing Environment - Sympatric Speciation (not yet published)

Sympatric speciation in a changing environment

(Click on images for large versions.)

In search of factors that have an influence on the rate of sympatric speciation we have found that besides of the recombination rate and quite obvious limited mating area, changes of an environment have also quite a big impact on this phenomenon.

Survival rate for population differ along with the pace of changes of the environment. If they occur very often (once in every 60 Monte Carlo steps or less) individuals accumulate less defects and then live longer.

Below you can see a chart showing the size of populations simulated with different recombination rates ranging from 0.01 to 0.99. The lower recombination rate the longer population survives. There is one change of the environment for every 250 MCs. This number is chosen because of best rendition of the phenomenon we want to introduce. If we increase this gap between changes to 500 populations will die out too fast, if we decrease this value to 60 or less most of the populations will last very long or forever.

Snapshots of the populations

Following images are snapshots taken after every thousand MCs starting from an MCs number 250. Each snapshot is taken 250 MCs after a change of the environment which takes places once in every 250 MCs just after the snapshot is taken. Because of the fact that there is 250 MCs after each change and before taking the snapshot populations are partially or fully recovered.

Recombination 0.01

Under such a low recombination one can observe very rapid speciation which in connection with limited mating distances result in formation of groups of tightly related individuals. Individuals incorporated in those groups share large parts of genome with all the acquired mutations.

Recombination 0.10

Along with the increase of recombination tendency to clustering very similar individuals declines. As a result individuals get less related to each other, they have smaller part of genome in common. Therefore, environmental changes start to kill less whole groups and killing looks more random.