We examined the allozyme variation of cottontail rabbits of the genus Sylvi
lagus from Mexico, and described their genic relationships. Samples of kidn
ey and heart were run in horizontal starch-gel electrophoresis to assess th
e variation of 23 presumptive loci, and the BIOSYS-1 software was used to c
ompute estimates of genic variation. Results showed that 60.8% of the loci
were polymorphic. S. floridanus was the most genically variable rabbit as r
evealed by mean number of alleles per locus and percentage of polymorphic l
oci. The fixation index showed genetic differentiation among species. The s
mallest genetic distance was between S. floridanus and S. brasiliensis wher
eas the largest one was between S. mansuetus and S. audubonii. A phenogram
showed S. mansuetus branching out first, S. audubonii next, and finally S.
floridanus and S. brasiliensis together. in conclusion, S. floridanus showe
d the largest genic variation, S. mansuetus was the most distinctive rabbit
, and S. audubonii and S. brasiliensis were the most closely related specie
s.