No evidence of genetic differentiation betweenlesser redpolls Carduelis flammea cabaret andcommon redpolls Carduelis f. flammea

The remarkable variation in plumage and morphological characters in the redpoll complexCarduelis flammea-hornemanni has puzzled taxonomists for several decades. In contrast,molecular studies have not revealed any genetic differentiation among the phenotypic redpollforms. This could either be a result of high present-day gene flow or morphological differentiationfollowing a rapid and recent population expansion. We sequenced a major portion(960 bp) of the mitochondrial control region in individuals of the two taxa Carduelis flammeaflammea and C. f. cabaret. Birds were sampled on autumn migration in southern Sweden(n = 30) and on breeding areas in southern Norway (n = 11). We found 22 variable sitesdefining 26 different haplotypes, of which most (22/26) were singletons. The level of haplotypeand nucleotide diversity was low in the two taxa and we found no evidence of geneticdifferentiation. A mismatch distribution was very similar to that expected from a sudden populationexpansion model. Our estimates suggest that the redpoll population expanded duringthe last glaciation episode from a small population to a long-term effective populationsize of 230 000 females. The findings in our study suggest that the morphological differentiationbetween the two taxa occurred rather recently but after the population expansion.

Richard Ottvall, Staffan Bensch, Goran Walinder and Jan T. Lifjeld, Avian Science Vol. 2 No. 4: 237-244 (2002)