On the origin of Lake Malawi cichlid species: A population genetic analysis of divergence

1. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 1.

   The IM model is depicted with two parameter sets. The basic demographic parameters are constant effective population sizes (N₁, N₂ and N_A), gene flow rates per gene copy per generation (m ₁ and m ₂), and the time of population splitting at t generations in the past. The parameters in the second set (in italics) are all scaled by the neutral mutation rate u, and these parameters are actually used in the model fitting.

   
   
2. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 2.

   Mutation rate scalars, estimated in separate analyses for each species pair, are plotted against the average amount of sequence divergence between Tropheops and Eretmodus. The scalars are the estimated mutation rates relative to other loci (including STRs that are not shown) obtained by fitting the data to the IM model. Points are grouped for each of the five loci for which divergence could be measured.

   
   
3. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 3.

   Probability estimates for the time of population splitting for two populations of each species. The time scale as been converted to years, based on mutation rate scalar estimates and outgroup divergence, as described in Methods.

   
   
4. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 4.

   Results for two populations of T. gracilior. Probability density estimates are shown for effective population sizes (Top) and migration rates from Otter Point to Harbor Isle (Middle) and from Harbor Isle to Otter Point (Bottom). The estimates for effective population size are given in the key in Top. The scales for migration rates are set by using these estimates of the effective population size (see Methods).

   
   
5. 

   View larger version:

   • In this window
   • In a new window

   • Download as PowerPoint Slide

   Fig. 5.

   Results for T. broad mouth and T. tropheops. Probability density estimates are shown for effective population sizes (Upper) and estimated time of divergence (Lower). The estimates for effective population size are given in the key.