J. Avian Biol. 41: 378Á387, 2010 doi: 10.1111/j.1600-048X.2009.04902.x # 2010 The Authors. J. Compilation # 2010 J. Avian Biol. Received 11 May 2009, accepted 16 December 2009 Population structure in the South American tern Sterna hirundinacea in the South Atlantic: two populations with distinct breeding phenologies Patrı´cia J. Faria, Fausto P. Campos, Joaquim O. Branco, Ce´zar M. Musso, Joa˜o S. Morgante and Michael W. Bruford P. J. Faria (
[email protected]) and J. S. Morgante, Dept. de Gene´tica e Biol. Evol., IB-USP, Sa˜o Paulo, SP, Brasil. Á PJF and M. W. Bruford, School of Biosci., Cardiff Univ., Cardiff, CF10 3AX, UK. Á F. P. Campos, Inst. Florestal, SMA, SP, Brasil. Á J. O. Branco, Cttmar, Univali, Itajaı´, SC, Brasil. Á C. M. Musso, Projeto Andorinhas-do-mar, AVIDEPA, Vila Velha, ES, Brasil. The South American tern Sterna hirundinacea is a migratory species for which dispersal, site fidelity and migratory routes are largely unknown. Here, we used five microsatellite loci and 799 bp partial mitochondrial DNA sequences (Cytochrome b and ND2) to investigate the genetic structure of South American terns from the South Atlantic Ocean (Brazilian and Patagonian colonies). Brazilian and Patagonian colonies have two distinct breeding phenologies (austral winter and austral summer, respectively) and are under the influence of different oceanographic features (e.g. Brazil and Falklands/Malvinas ocean currents, respectively), that may promote genetic isolation between populations. Results show that the Atlantic populations are not completely panmictic, nevertheless, contrary to our expectations, low levels of genetic structure were detected between Brazilian and Patagonian colonies.