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Gene flow and concerted evolution
Phylogenetic studies that use nuclear ribosomal ITS sequences usually stress the negative impact of finding intra-genomic variability. By adopting a fine-scale focus on southern Spanish populations of thrifts, Nieto Feliner et al. (pp. 189-200) confirm and provide insights into the unusual -- and species-independent -- geographic structure of variation shown by this marker. The results support an evolutionary role, in the genus, for hybridization.
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