Abstract:
Blood serum and egg-white protein samples from individuals representing
seven colonies of Larusargentatus, and four colonies of Sterna hirundo
were electrophoretically analysed to determine levels of genetic variability
and to assess the utility of polymorphic loci as genetic markers.
Variability occurred at five co-dominant autosomal loci. S. hirundo protein
polymorphism occurred at the Est-5 and the Oest-l loci, while nineteen loci
were monomorphic. L. argentatus samples were monomorphic at seventeen loci
and polymorphic at the Ldh-A and the Alb loci. Intergeneric differences
existed at the Oalb and the Ldh-A loci. Although LDH-A100 from both species
possessed identical electrophoretLc mobilities, the intergeneric differences
were expressed as a difference in enzyme the'ITIlostabilities.
Geographical distribution of alleles and genetic divergence estimates
suggest ~ hirundo population panmixis,at least at the sampled locations.
The h argentatus gene pool appears relatively heterogeneous with a discreet
Atlantic Coast population and a Great Lakes demic population. These
observed population structures may be maintained by the relative amount of
gene flow occurring within and among populations. Mass ringing data coupled
to reproductive success information and analysis of dispersal trends appear
to validate this assumption. Similar results may be generated by either
selection or both small organism and low locus sample sizes. To clarify
these results and to detect the major factor(s) affecting the surveyed
portions of the genome, larger sample sizes in conjunction with precise
eco-demographic data are required.
