Vigfúsdóttir F, Pálsson S, Ingólfsson A.. Hybridization of glaucous gull (Larus hyperboreus) and herring gull (Larus argentatus) in Iceland: mitochondrial and microsatellites data. Phil Trans R Soc B 363: 2851-2860

Department of Biology, University of Iceland, Sturlugata 7, 101 Reykjavík, Iceland.
Philosophical Transactions of The Royal Society B Biological Sciences (Impact Factor: 7.06). 06/2008; 363(1505):2851-60. DOI: 10.1098/rstb.2008.0042
Source: PubMed


Large white-headed gulls provide an interesting group of birds for studies of hybridization. The group is composed of 20 species of recent origin, often with weak reproductive barriers. Here we report the results from a study on the glaucous gull Larus hyperboreus, an Arctic species which has been breeding in Iceland for centuries, and the herring gull Larus argentatus which has a wide distribution in Europe but colonized Iceland in 1920s. Previous studies, based on morphological variation indicated hybridization between the two species in Iceland, have been questioned as it may just reflect variation within the species. Here we evaluate whether hybridization has occurred between the two species in Iceland by studying variation in microsatellites and mtDNA. The analysis is based on feathers taken from wings sampled in Iceland over a period of 40 years. The results are compared with samples obtained from East Greenland and published sequences of samples obtained throughout Europe. The genetic analysis reveals a distinctive grouping of the two species, although they present a shallow genealogy and an extensive sharing of the genetic variants between the two species. Several individuals show admixture for molecular markers, which may result from an incomplete lineage sorting although geographical patterns of both mtDNA haplotypes and microsatellites strongly indicate a recent hybridization in Iceland.

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    • "Gulls Laridae hybridize relatively frequently, and over a half of species from this group is known to hybridize (Pierotti 1987, Panov 1989, Pierotti & Annett 1993, McCarthy 2006, Price 2008). Existing hybrid zones of gulls have frequently been formed due to range expansions and colonizations of new areas (Bell 1996, 1997, Good et al. 2000, Gay et al. 2007, Vigfúsdóttir et al. 2008, Pálsson et al. 2009). Our model species are Herring Larus argentatus and Caspian L. cachinnans Gulls, which both have invaded central-European lowlands expanding from opposite directions, the former from the north and the latter from the south-east (Neubauer et al. 2006). "
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    ABSTRACT: Following range expansion and colonization, hybridization between Herring and Caspian Gulls, Larus argentatus and L. cachinnans, takes place in central and eastern Europe. To examine how hybrid zone is affected by the abundance dynamics of these species and their reproductive performance, we studied a mixed colony at Włocławek Reservoir, central Poland, for over 7 years, from 2002 to 2009, and included data from the species monitoring from 1990 to 2001. To evaluate the species abundance dynamics and possible mechanisms of reproductive isolation, breeders (n = 226 individual birds) were trapped on nests and colour-ringed; breeding performance was studied in detail for 202 breeding pairs with both mates known. Between 2002 and 2009 the proportion of Caspian Gulls among breeders had strongly increased (from 14% to 42%), whereas the proportion of Herring Gulls had declined (from 70% to 35%). The frequency of hybrids varied a little with no clear trend (mean 20%, range 15–28%). The colony size during that time was approximately stable, with 125–135 breeding pairs. 32 individuals originating from outside the zone, ringed as nestlings in the core range of either species, were recorded as breeders at the study site, documenting dispersal of parental species into the zone. The immigration of the two parental species showed contrasting temporal patterns in the two compared decades, 1990–1999 vs. 2000–2009. The immigration of Herring Gulls as measured by the reencounter probability declined nearly three times, while approximately twofold increase was seen in Caspian Gulls. Birds tended to choose phenotypically similar mates, so that there were fewer heterospecific pairs than expected under random mating. Numbers of homospecific, heterospecific and mixed pairs were similar during 7 years. On average, males of Caspian Gulls were significantly heavier than males of Herring Gulls. Caspian Gull pairs bred on average 7 days earlier than pairs of Herring Gulls. No differences in clutch size, clutch volume or hatching success among pairs of different composition were found, indicating weak postzygotic isolation. Current abundance of species in the hybrid zone is changing dynamically and is primarily driven by the strength of immigration from outside the zone.
    Acta Ornithologica 12/2012; 47(2). DOI:10.3161/000164512X662296 · 0.75 Impact Factor
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    • "For hyperboreus, the most likely scenario explaining their present biphyletic mtDNA distribution is a process whereby Nearctic hyperboreus invaded into northern argentatus refugia. After some time, upon complete replacement of their original clade 2 mtDNA haplotypes by argentatus derived clade 1 haplotypes, they again became more-or-less reproductively isolated (but see [10]). As a consequence of this process, Palearctic hyperboreus now strictly displays clade 1 mtDNA haplotypes, but still remain genetically more similar in their autosomes to their closely related Nearctic ancestors (also including smithsonianus). "
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    ABSTRACT: Based on extensive mitochondrial DNA (mtDNA) sequence data, we previously showed that the model of speciation among species of herring gull (Larus argentatus) complex was not that of a ring species, but most likely due more complex speciation scenario's. We also found that two species, herring gull and glaucous gull (L. hyperboreus) displayed an unexpected biphyletic distribution of their mtDNA haplotypes. It was evident that mtDNA sequence data alone were far from sufficient to obtain a more accurate and detailed insight into the demographic processes that underlie speciation of this complex, and that extensive autosomal genetic analysis was warranted. For this reason, the present study focuses on the reconstruction of the phylogeographic history of a limited number of gull species by means of a combined approach of mtDNA sequence data and 230 autosomal amplified fragment length polymorphism (AFLP) loci. At the species level, the mtDNA and AFLP genetic data were largely congruent. Not only for argentatus and hyperboreus, but also among a third species, great black-backed gull (L. marinus) we observed two distinct groups of mtDNA sequence haplotypes. Based on the AFLP data we were also able to detect distinct genetic subgroups among the various argentatus, hyperboreus, and marinus populations, supporting our initial hypothesis that complex demographic scenario's underlie speciation in the herring gull complex. We present evidence that for each of these three biphyletic gull species, extensive mtDNA introgression could have taken place among the various geographically distinct subpopulations, or even among current species. Moreover, based on a large number of autosomal AFLP loci, we found evidence for distinct and complex demographic scenario's for each of the three species we studied. A more refined insight into the exact phylogeographic history within the herring gull complex is still impossible, and requires detailed autosomal sequence information, a topic of our future studies.
    BMC Evolutionary Biology 11/2010; 10(1):348. DOI:10.1186/1471-2148-10-348 · 3.37 Impact Factor
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    • "The samples of Herring Gulls that Snell studied were similar in both weight and HI to the more recent Herring Gull samples from eastern Iceland. There could be several explanations for this slight increase in HI score from the earliest sample (a1), including the extinction of the colony of Glaucous Gulls (h1e) breeding in southeastern Iceland, selection counteracting the effect of hybridization, undetected population structure, and a possible influx of Herring Gulls migrating from Europe (Vigfúsdóttir et al. 2008). Interestingly, Glaucous Gulls are approaching the weight of Herring Gulls, even though the HI values of the former group are, on average, decreasing. "
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    ABSTRACT: Recent hybridization has been reported between the Herring Gull (Larus argentatus) and Glaucous Gull (Larus hyperboreus; the larger of the species) in Iceland, after the arrival of Herring Gulls around 1925. We used samples of both species from various locations in Iceland and from three periods spanning >40 years. To analyze the nature of hybridization and the extent of introgression between the species, we compared morphological variation using genetic information based on microsatellite and mtDNA data. Both comparisons of single traits and multivariate analysis pointed to hybridization and introgression. Variation in genetic markers and morphological traits revealed two distinct groups, connected by a number of intermediates. A discrepancy in classification based on genetic or morphological information revealed introgression. Variation within each species reflected the effect of hybridization; for example, individuals with less pigmentation (i.e., more hyperboreus-like) tend to be larger. The differences we observed among samples and periods reflect changes in the overlap of the populations’ distributions.
    The Auk 04/2009; 126(2):376-382. DOI:10.1525/auk.2009.08080 · 1.86 Impact Factor
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