ABSTRACT
The white-faced ibis Plegadis chihi Vieillot, 1817 (Pelecaniformes: Threskiornithidae) is a socially monogamous colonially breeding bird in which behavioral and ecological observations suggest the occurrence of conspecific brood parasitism (CBP). We inferred aspects of the genetic mating system of P. chihi in nature, using a genetic approach in the absence of parental information. We used five heterologous microsatellite loci and a multiple-step methodological approach to infer kinship patterns among 104 pairs of nestlings sampled inside 80 nests in a breeding colony from southern Brazil. The estimated effective population size was 69 white-faced ibises (95% CI: 50-98), enough to ensure long-term population survival. Kinship patterns were identified for 38% of the analyzed pairs: 60% of the diagnosed pairs were identified as full-siblings, 2.5% as half-siblings and 37.5% as unrelated individuals. CBP could explain the presence of unrelated nestlings within broods, in agreement with available non-genetic evidence. The presence of half-siblings within broods could indicate extra-pair paternity. Results suggest that a non-strictly monogamous genetic mating system may be present in the white-faced ibis. This study is the first molecular approach to better characterize the reproductive behavior of P. chihi in the wild. Our findings set the stage for further research to investigate the possible causes and consequences of alternative reproductive strategies in this species.
Subject(s)
Birds/genetics , Microsatellite Repeats/genetics , Reproduction/genetics , Social Behavior , Animals , Birds/physiology , Brazil , Reproduction/physiologyABSTRACT
We screened 44 heterologous microsatellites isolated in species of the families Threskiornithidae, Ciconiidae and Ardeidae for their use in a migratory waterbird, the white-faced ibis Plegadis chihi (Vieillot, 1817) (Threskiornithidae). Of the screened loci, 57% amplified successfully and 24% were polymorphic. In two breeding colonies from southern Brazil (N = 131) we detected 32 alleles (2-10 alleles/locus). Average He over all loci and colonies was 0.55, and the combined probability of excluding false parents, 98%. There was no departure from HWE in any loci or population. Eru6 and Eru4 loci were in non-random association in the Alvorada colony, and NnNF5 and Eru5 in both populations. AMOVA analysis indicated that most of the genetic diversity was contained within populations. Structure analysis suggested a single population, and F(ST) value showed weak genetic structuring (F(ST) = 0.009, p = 0.05). The two populations are apparently connected through gene-flow. The panel of six microsatellites optimized here was sufficiently informative for characterizing the genetic diversity and structure in these natural populations of the white-faced ibis. The information generated could be useful in future studies of genetic diversity, relatedness and the mating system in Plegadis chihi and related species.
