Ak. Fridolfsson et al., MICROSATELLITE MARKERS FOR PATERNITY TESTING IN THE WILLOW WARBLER PHYLLOSCOPUS-TROCHILUS - HIGH-FREQUENCY OF EXTRA-PAIR YOUNG IN AN ISLANDPOPULATION, Hereditas, 126(2), 1997, pp. 127-132
Four microsatellite markers from the willow warbler Phylloscopus troch
ilus: were isolated and characterised. The combined exclusion probabil
ity of the three most polymorphic markers (Phtr1, Phtr2 and Phtr3) was
0.96. These markers were used to test for the occurrence of extra-pai
r young (EPY) in twelve willow warbler families sampled from the islan
d of Gotland in 1992 and 1993. The mean frequency of extra-pair young
was found to be 28 % and the mean frequency of families with extra-pai
r young 58 %. These results contrast with an earlier study in a mainla
nd Swedish population, where no EPY were found. The island population
in this study has a higher breeding density than the mainland populati
on, rendering support For density dependent factors affecting the freq
uency of EPY. A cross-species study showed that the willow warbler mic
rosatellite markers can also be used in other European passerines as w
ell as distantly related species, such as the Australian magpie Gymnor
hina tibicen.