title: Historical DNA reveals the demographic history of Atlantic cod (Gadus morhua) in medieval and early modern Iceland.
abstract: Atlantic cod (Gadus morhua) vertebrae from archaeological sites were used to study the history of the Icelandic Atlantic cod population in the time period of 1500-1990. Specifically, we used coalescence modelling to estimate population size and fluctuations from the sequence diversity at the cytochrome b (cytb) and Pantophysin I (PanI) loci. The models are consistent with an expanding population during the warm medieval period, large historical effective population size (NE), a marked bottleneck event at 1400-1500 and a decrease in NE in early modern times. The model results are corroborated by the reduction of haplotype and nucleotide variation over time and pairwise population distance as a significant portion of nucleotide variation partitioned across the 1550 time mark. The mean age of the historical fished stock is high in medieval times with a truncation in age in early modern times. The population size crash coincides with a period of known cooling in the North Atlantic, and we conclude that the collapse may be related to climate or climate-induced ecosystem change.
authors.affiliation: Research Centre of the Westfjords, University of Iceland, , Adalstraeti 21, IS415 Bolungarvik, Iceland, VÖR Marine Research Centre, , Nordurtangi, IS355 Snæfellsbær, Iceland, Department of Environmental and Life Science, University of Iceland, , Sturlugata 7, IS101 Reykjavík, Iceland.
authors.forename: Guðbjörg Ásta
authors.initials: GÁ
authors.lastname: Ólafsdóttir
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Westfall
authors.forename: Ragnar
authors.initials: R
authors.lastname: Edvardsson
authors.forename: Snæbjörn
authors.initials: S
authors.lastname: Pálsson
mesh_terms: D000818:Animals; D002980:Climate; D045303:Cytochromes b / Q000235:genetics / Q000378:metabolism; D003710:Demography; D017753:Ecosystem; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D048389:Gadus morhua / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D007055:Iceland; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011157:Population Dynamics; D017422:Sequence Analysis, DNA; D013131:Spine / Q000737:chemistry; D016708:Synaptophysin / Q000235:genetics / Q000378:metabolism; D013997:Time Factors
chemical_list: D029941:Fish Proteins; D024101:Mitochondrial Proteins; D016708:Synaptophysin; D045303:Cytochromes b
keywords: Atlantic cod; ancient DNA; coalescence modelling; effective population size