Low levels of genetic variability in North American populations of the Wood Stork (Mycteria americana)

The breeding population of Wood Storks (Mycteria americana) in the southeas tern United States has declined since the 1930s, resulting in the listing o f all United States populations of the species as endangered in 1984. We as sessed genetic structure within and among nine colonies of Wood Storks from Georgia and Florida. Levels of band sharing based on multilocus oligonucle otide DNA fingerprinting of individuals from seven colonies ranged from 58% among nests within the same tree to approximately 55% within the same colo ny. Levels of band sharing were similar to those reported for other populat ions of birds that have experienced drastic reductions in population size. A more thorough analysis of four polymorphic microsatellite loci for 136 in dividuals from nine colonies indicated low levels of allelic diversity and low genetic divergence among colonies. Generic differentiation (F-ST = 0.01 5) was similar to levels detected from allozymes for 15 colonies of Wood St orks in Florida (F-ST = 0.019). These data, together with demographic studi es of these populations, indicated high levels of gene flow among colonies (N-m = 16.4). In agreement with previous studies, we recommend that all col onies of Wood Storks in the southeastern United States be managed on a regi onal basis as a single interbreeding population. Similar genetic surveys of the disjunct breeding populations of Wood Storks in South America and Cent ral America would be beneficial in understanding the total genetic differen tiation in the species.