RELATIVE WARP ANALYSIS OF SKULL SHAPE ACROSS THE HYBRID ZONE OF THE HOUSE MOUSE (MUS MUSCULUS) IN DENMARK

The changes in skull shape that occur in the hybrid zone between the t wo European subspecies of the house mouse (Mus musculus musculus and M . m. domesticus) were studied by relative warp analyses. Landmarks obs erved on the ventral view of the skulls of 269 mice sampled in IS loca lities in Denmark were analysed. Each population was also characterize d by a hybrid index estimated from allozymic data. Although no clear p attern of within-population variability of shape could be established across the hybrid zone, the shape changes among the 18 populations wer e found to be correlated with the allozymic introgression but not with geographical location. Finally, the cline obtained for skull shape se ems to be steeper than that corresponding to the average allozyme hybr id index which suggests that skull development could be slightly pertu rbed in hybrids.