Archaeoentomology reconstructs past environments and human activities through the analysis of insect remains preserved in archaeological deposits. Although different arthropod groups can be identified when preservation conditions allow, taxonomic resolution often depends on the preservation of diagnostic sclerotized structures, which limits the detection of poorly preserved or very small taxa. Here, we evaluate whether ancient sedimentary DNA (sedaDNA) can complement conventional morphological identifications and provide comparable and reproducible information from the same archaeological samples. We analyzed sediments from two water-saturated Gallo-Roman wells in France using a metabarcoding approach and directly compared the molecular results with morphological identifications made on the corresponding layers. Several groups detected by sedaDNA were absent from the morphological assemblages, despite being ecologically plausible in the studied contexts. Conversely, some beetle taxa, despite being well represented morphologically, were not detected in the DNA data. SedaDNA and morphological data revealed different communities for the two wells. One well exhibited low taxonomic and phylogenetic diversity and was largely dominated by bird mites, generalist decomposers, and other weakly sclerotized arthropods, while the other well had greater overall diversity and was dominated by insects associated with an open environment, likely consisting of arable land. Despite these differences in taxonomic composition, these results highlight the role of local environmental conditions and human practices in shaping distinct arthropod communities at the two archaeological sites. By integrating molecular and morphological data, this comparison demonstrates that sedaDNA does not replace the fossil record but expands the detectable fraction of the arthropod community.
Despite the known influence of climate change on high-altitude ecosystems, the long-term response of prokaryotic communities in Mediterranean high-mountain lakes remains poorly understood. Here, we investigate the temporal dynamics of prokaryotic communities over the past ~ 430 years in a Mediterranean high-mountain lake, utilizing sedimentary ancient DNA (sedDNA). By examining a sediment core from Borreguil Lake in the Sierra Nevada (Spain), we evaluated bacterial and archaeal abundance, diversity, and community composition (β-diversity) in relation to paleoenvironmental and climate data. Our findings revealed a significant restructuring of prokaryotic communities, particularly since ca. 1960. A Random Forest model identified dissolved organic carbon, organic nitrogen, Saharan atmospheric dust inputs, and temperature as key drivers of the abundance, diversity, and composition of prokaryotic communities, particularly in the modern era. Notably, the abundance and diversity of bacterial communities increased in response to increased dissolved organic carbon, elevated temperatures, and dust deposition, while archaea demonstrated a more nuanced response linked to organic nitrogen availability and dust inputs. The temporal shifts in microbial community composition point to broader ecological changes within the lake, shaped by climate-driven environmental variations. For example, the increased relative abundance of Cyanobacteria and other taxa linked to higher nutrient availability indicates ongoing eutrophication processes, likely intensified by climate warming. This study highlights the importance of high-mountain lakes as indicators of climate change, contributing valuable insights into microbial ecology’s response to long-term environmental change. Our findings offer a foundational understanding for predicting microbial responses in sensitive ecosystems under future climate scenarios.
New article in IA69 by Vince Gaffney and colleagues on the Neolithic pit structure at #Durrington Walls Henge includes new #OSL dates and #sedaDNA environmental studies. Results indicate a cohesive pit structure at a massive scale.
In 2020, a series of large features were identified, set within two arc-like structures, to the north and south of Durrington Walls henge (Gaffney et al. 2020). Based on geophysical survey and borehole investigation, combined with the results of previous, commercial fieldwork, 15 features were interpreted as either large pits or probable pits. Five additional features were identified from aerial photography or topographic modelling as being of potential interest. Some of these features, on the 'northern arc', were assessed by their original investigators to be naturally occurring sinkholes (Leivers 2021). Following the interpretation of these features as a single pit alignment, some discussion has taken place relating to the origin and nature of these features and their association with Durrington Walls henge (Ruggles and Chadburn 2024). This debate has taken place without the benefit of the results of more recent research undertaken both in the field and laboratory. In 2021, further investigations were carried out over 'northern arc' features 13D and 16D, as well as over the 'southern arc' features 1A, 2A, 3A, 4A. This work also provided an opportunity to survey anomaly ii at Larkhill, and to revisit 'southern arc' features 5A, 7A and 8A. The latter three had been surveyed and cored in 2019 and identified as pits. New fieldwork also provided the occasion to utilise a wider range of analytical techniques than previously, and the application of novel geochemistry and sedaDNA methods generated sediment stratigraphies and detailed environmental histories for individual pits. The results of geophysical survey and borehole investigations reinforce the overall similarity between those features previously identified as pits or probable pits, as well as those investigated in the recent field campaign. Consequently, with confirmation of pit 16D as a new addition to the 'northern arc', the total of pits/probable pits in the overall series has risen to 16. However, to the west of Durrington Walls, in Larkhill, a magnetometer survey over anomaly ii did not reveal a magnetic response consistent with a large pit-feature, although this area is heavily disturbed by later development and the survey results at this location cannot be regarded as conclusive. Currently, the majority of features identified during the two seasons of work at Durrington continue to be interpreted as corresponding to large pits or modified features which, irrespective of any possible natural origin, emerged during the later Neolithic to form part of a larger, prehistoric pit structure surrounding Durrington Walls.
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