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• Garcia, Lourdes Martinez; Cuevas, Angelica; Ferrari, Giada; Hufthammer, Anne Karin; Vedeler, Marianne & Hirons, Alex [Vis alle 9 forfattere av denne artikkelen] (2024). Tracing 600 years of long-distance Atlantic cod trade in medieval and post-medieval Oslo using stable isotopes and ancient DNA. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 291(2035). doi: 10.1098/rspb.2024.2019. Fulltekst i vitenarkiv Vis sammendrag

  Marine resources have been important for the survival and economic development of coastal human communities across northern Europe for millennia. Knowledge of the origin of such historic resources can provide key insights into fishing practices and the spatial extent of trade networks. Here, we combine ancient DNA and stable isotopes (δ13C, δ15N, non-exchangeable δ2H and δ34S) to investigate the geographical origin of archaeological cod remains in Oslo from the eleventh to seventeenth centuries CE. Our findings provide genetic evidence that Atlantic cod was obtained from different geographical populations, including a variety of distant-water populations like northern Norway and possibly Iceland. Evidence for such long-distance cod trade is already observed from the eleventh century, contrasting with archaeological and historical evidence from Britain and other areas of Continental Europe around the North and Baltic Seas, where such trade increased during the thirteenth to fourteenth centuries. The genomic assignments of specimens to different populations coincide with significantly different δ13C values between those same specimens, indicating that multiple Atlantic cod populations living in different environments were exploited. This research provides novel information about the exploitation timeline of specific Atlantic cod stocks and highlights the utility of combining ancient DNA (aDNA) methods and stable isotope analysis to describe the development of medieval and post-medieval marine fisheries.

• Garcia, Lourdes Martinez; Ferrari, Giada; Cuevas, Angelica; Atmore, Lane Margaret; López-Arias, Begoña & Culling, Mark [Vis alle 18 forfattere av denne artikkelen] (2022). Ancient DNA evidence for the ecological globalization of cod fishing in medieval and post-medieval Europe. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 289(1985). doi: 10.1098/rspb.2022.1107. Fulltekst i vitenarkiv Vis sammendrag

  Understanding the historical emergence and growth of long-range fisheries can provide fundamental insights into the timing of ecological impacts and the development of coastal communities during the last millennium. Whole-genome sequencing approaches can improve such understanding by determining the origin of archaeological fish specimens that may have been obtained from historic trade or distant water. Here, we used genome-wide data to individually infer the biological source of 37 ancient Atlantic cod specimens (ca 1050–1950 CE) from England and Spain. Our findings provide novel genetic evidence that eleventh- to twelfth-century specimens from London were predominantly obtained from nearby populations, while thirteenth- to fourteenth-century specimens were derived from distant sources. Our results further suggest that Icelandic cod was indeed exported to London earlier than previously reported. Our observations confirm the chronology and geography of the trans-Atlantic cod trade from Newfoundland to Spain starting by the early sixteenth century. Our findings demonstrate the utility of whole-genome sequencing and ancient DNA approaches to describe the globalization of marine fisheries and increase our understanding regarding the extent of the North Atlantic fish trade and long-range fisheries in medieval and early modern times.

• Garcia, Lourdes Martinez; Ferrari, Giada; Hufthammer, Anne Karin; Jakobsen, Kjetill Sigurd; Jentoft, Sissel & Barrett, James Harold [Vis alle 7 forfattere av denne artikkelen] (2022). Ancient DNA reveals a southern presence of the Northeast Arctic cod during the Holocene. Biology Letters. ISSN 1744-9561. 18(5). doi: 10.1098/rsbl.2022.0021. Fulltekst i vitenarkiv Vis sammendrag

  Climate change has been implicated in an increased number of distributional shifts of marine species during the last century. Nonetheless, it is unclear whether earlier climatic fluctuations had similar impacts. We use ancient DNA to investigate the long-term spawning distribution of the Northeast Arctic cod (skrei) which performs yearly migrations from the Barents Sea towards spawning grounds along the Norwegian coast. The distribution of these spawning grounds has shifted northwards during the last century, which is thought to be associated with food availability and warming temperatures. We genetically identify skrei specimens from Ruskeneset in west Norway, an archaeological site located south of their current spawning range. Remarkably, 14C analyses date these specimens to the late Holocene, when temperatures were warmer than present-day conditions. Our results either suggest that temperature is not the only driver influencing the spawning distribution of Atlantic cod, or could be indicative of uncertainty in palaeoclimate reconstructions in this region. Regardless, our findings highlight the utility of aDNA to reconstruct the historical distribution of economically important fish populations and reveal the complexity of long-term ecological interactions in the marine environment.

• Atmore, Lane Margaret; Ferrari, Giada; Garcia, Lourdes Martinez; Jagt, Inge van der; Blevis, Rachel & Granado, José [Vis alle 14 forfattere av denne artikkelen] (2022). Ancient DNA sequence quality is independent of fish bone weight. Journal of Archaeological Science. ISSN 0305-4403. 149. doi: 10.1016/j.jas.2022.105703. Fulltekst i vitenarkiv Vis sammendrag

  The field of ancient DNA (aDNA) typically uses between 50 and 200 mg of minimum input weight of bone material for the extraction of DNA from archaeological remains. While laboratory and analysis techniques have focused on improved efficiency of extracting useable sequence data from older and poorer quality remains, bone material input requirements have rarely been critically evaluated. Here, we present the aDNA analysis of 121 size-constrained Atlantic herring remains – weighing between <10 and 70 mg – that were individually sequenced to explore the capacity of successful aDNA retrieval from small archaeological remains. We statistically evaluate the relationship between bone weight and several response variables, including library success, endogenous DNA content, and library complexity, i.e., the number of unique molecules that are obtained. Remarkably, we find no relationship between bone weight and library success, levels of endogenous DNA, or library complexity. Our results imply that – at least in the case of fish bone – even minute bones can yield positive results and that the presumed minimum sample size required should be re-evaluated. Archaeological site, instead of bone size, is the primary driver of DNA sequence quality. Our work expands the number of specimens considered suitable for aDNA analyses, and therefore facilitates efforts to minimize the destructive impact of aDNA research and mediate some of the ethical concerns surrounding destructive analysis.

• Atmore, Lane Margaret; Garcia, Lourdes Martinez; Makowiecki, Daniel; André, Carl; Lõugas, Lembi & Barrett, James [Vis alle 7 forfattere av denne artikkelen] (2022). Population dynamics of Baltic herring since the Viking Age revealed by ancient DNA and genomics. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 119(45). doi: 10.1073/pnas.2208703119. Fulltekst i vitenarkiv Vis sammendrag

  The world’s oceans are currently facing major stressors in the form of overexploitation and anthropogenic climate change. The Baltic Sea was home to the first “industrial” fishery ∼800 y ago targeting the Baltic herring, a species that is still economically and culturally important today. Yet, the early origins of marine industries and the long-term ecological consequences of historical and contemporary fisheries remain debated. Here, we study long-term population dynamics of Baltic herring to evaluate the past impacts of humans on the marine environment. We combine modern whole-genome data with ancient DNA (aDNA) to identify the earliest-known long-distance herring trade in the region, illustrating that extensive fish trade began during the Viking Age. We further resolve population structure within the Baltic and observe demographic independence for four local herring stocks over at least 200 generations. It has been suggested that overfishing at Øresund in the 16th century resulted in a demographic shift from autumn-spawning to spring-spawning herring dominance in the Baltic. We show that while the Øresund fishery had a negative impact on the western Baltic herring stock, the demographic shift to spring-spawning dominance did not occur until the 20th century. Instead, demographic reconstructions reveal population trajectories consistent with expected impacts of environmental change and historical reports on shifting fishing targets over time. This study illustrates the joint impact of climate change and human exploitation on marine species as well as the role historical ecology can play in conservation and management policies.

• Oosting, Tom; Garcia, Lourdes Martinez; Ferrari, Giada; Verry, Alexander J. F.; Scarsbrook, Lachie & Rawlence, Nicolas J. [Vis alle 9 forfattere av denne artikkelen] (2022). Mitochondrial genomes reveal mid-Pleistocene population divergence, and post-glacial expansion, in Australasian snapper (Chrysophrys auratus). Heredity. ISSN 0018-067X. 130, s. 30–39. doi: 10.1038/s41437-022-00579-1. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Glacial cycles play important roles in determining the phylogeographic structure of terrestrial species, however, relatively little is known about their impacts on the distribution of marine biota. This study utilised modern ( n  = 350) and ancient ( n  = 26) mitochondrial genomes from Australasian snapper ( Chrysophrys auratus ) sampled in New Zealand to assess their demographic and phylogeographic history. We also tested for changes in genetic diversity using the up to 750-year-old mitochondrial genomes from pre-European archaeological sites to assess the potential impacts of human exploitation. Nucleotide diversity and haplotype diversity was high (π = 0.005, h   =  0.972). There was no significant change in nucleotide diversity over the last 750 years ( p  = 0.343), with no detectable loss of diversity as a result of indigenous and industrial-scale fishing activity. While there was no evidence for contemporary population structure (AMOVA, p  = 0.764), phylogeographic analyses identified two distinct mitochondrial clades that diverged approximately 650,000 years ago during the mid-Pleistocene, suggesting the species experienced barriers to gene flow when sea levels dropped over 120 m during previous glacial maxima. An exponential population increase was also observed around 8000 years ago consistent with a post-glacial expansion, which was likely facilitated by increased ocean temperatures and rising sea levels. This study demonstrates that glacial cycles likely played an important role in the demographic history of C. auratus and adds to our growing understanding of how dynamic climatic changes have influenced the evolution of coastal marine species.

• Garcia, Lourdes Martinez; Ferrari, Giada; Oosting, Tom; Ballantyne, Rachel; Jagt, Inge van der & Ystgaard, Ingrid [Vis alle 20 forfattere av denne artikkelen] (2021). Historical demographic processes dominate genetic variation in ancient Atlantic cod mitogenomes. Frontiers in Ecology and Evolution. 9, s. 1–14. doi: 10.3389/fevo.2021.671281. Fulltekst i vitenarkiv Vis sammendrag

  Ancient DNA (aDNA) approaches have been successfully used to infer the long-term impacts of climate change, domestication, and human exploitation in a range of terrestrial species. Nonetheless, studies investigating such impacts using aDNA in marine species are rare. Atlantic cod (Gadus morhua), is an economically important species that has experienced dramatic census population declines during the last century. Here, we investigated 48 ancient mitogenomes from historical specimens obtained from a range of archeological excavations in northern Europe dated up to 6,500 BCE. We compare these mitogenomes to those of 496 modern conspecifics sampled across the North Atlantic Ocean and adjacent seas. Our results confirm earlier observations of high levels of mitogenomic variation and a lack of mutation-drift equilibrium—suggestive of population expansion. Furthermore, our temporal comparison yields no evidence of measurable mitogenomic changes through time. Instead, our results indicate that mitogenomic variation in Atlantic cod reflects past demographic processes driven by major historical events (such as oscillations in sea level) and subsequent gene flow rather than contemporary fluctuations in stock abundance. Our results indicate that historical and contemporaneous anthropogenic pressures such as commercial fisheries have had little impact on mitogenomic diversity in a wide-spread marine species with high gene flow such as Atlantic cod. These observations do not contradict evidence that overfishing has had negative consequences for the abundance of Atlantic cod and the importance of genetic variation in implementing conservation strategies. Instead, these observations imply that any measures toward the demographic recovery of Atlantic cod in the eastern Atlantic, will not be constrained by recent loss of historical mitogenomic variation.

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• Kersten, Oliver Sven; Garcia, Lourdes Martinez; Pulido, Angélica; Ferrari, Giada; Baalsrud, Helle Tessand & Helmerson, Cecilia [Vis alle 18 forfattere av denne artikkelen] (2024). Long-term population dynamics of Atlantic cod revealed by Ancient DNA and Genomics. Fulltekst i vitenarkiv
• Garcia, Lourdes Martinez (2021). The mitogenomic structure of Atlantic cod investigated using ancient DNA. Fulltekst i vitenarkiv Vis sammendrag

  Atlantic cod is an economically important species distributed in the North Atlantic Ocean and adjacent seas. Although this species has a fundamental ecological role in marine ecosystems, continuous large-scale fishing activities have led to the decline and collapse of several populations during the last century. The genomic consequences of such declines, however, remain unclear. Here, we compare 48 ancient Atlantic cod mitogenomes dated up to 6500 BC to 496 modern mitogenomes sampled across the North Atlantic. We investigate whether any population bottlenecks or loss of mitogenomic variation can be associated with historical or recent demographic fluctuations. Our results reveal a high genetic mtDNA diversity with a low genetic spatial structure across large geographical scales. Furthermore, our temporal comparisons did not detect a significant loss of mitogenomic variation during the last millennia. Instead, mitogenomic variation in Atlantic cod reflects past demographic processes, such as population expansions driven by the interglacial and warming periods experienced during the last glaciations, rather than contemporary fluctuations in stock abundance. Our results indicate that recent anthropogenic impacts such as fisheries, have had little impact on ancient mitogenomic diversity in a wide-spread marine species with high gene flow such as Atlantic cod. Finally, our observations show that conservation management measures aimed towards demographic recovery will not be constrained by irreversible loss of mitogenomic variation.

• Ferrari, Giada; Garcia, Lourdes Martinez; Berg-Hansen, Inger Marie; Mansrud, Anja & Star, Bastiaan (2020). Ancient DNA of Tuna bones from the Alveberget excavation in Arendal, Norway. Universitetet i Oslo. Fulltekst i vitenarkiv

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