Larus - Ring Species

Ring Species

The circumpolar group of Larus gull species has often been cited as a classic example of the ring species. The range of these gulls forms a ring around the North Pole. The Herring Gull, which lives primarily in Great Britain, can hybridize with the American Herring Gull (living in North America), which can also interbreed with the Vega or East Siberian Herring Gull, the western subspecies of which, Birula's Gull, can hybridize with Heuglin's gull, which in turn can interbreed with the Siberian Lesser Black-backed Gull (all four of these live across the north of Siberia). The last is the eastern representative of the Lesser Black-backed Gulls back in northwestern Europe, including Great Britain. However, the Lesser Black-backed Gulls and Herring Gull are sufficiently different that they cannot interbreed; thus the group of gulls forms a continuum except in Europe where the two lineages meet. However, a recent genetic study has shown that this example is far more complicated than presented here, and probably does not constitute a true ring species (Liebers et al., 2004).