Uncertainty in coprophilous fungal spore concentration estimates

The abundance of coprophilous (dung-inhabiting) fungal spores (CFS) in sedimentary records is an increasingly popular proxy for past megaherbivore abundance that is used to study megaherbivore-vegetation interactions, timing of megaherbivore population declines and extinctions, and the introduction of domesticated herbivores. This method often relies on counting CFS alongside pollen and tracers of known concentration such as exotic pollen or synthetic microspherules. Prior work has encouraged reporting CFS abundances as accumulation rates (spores/unit2/year) or concentration (spores/unit3) instead of percentages relative to the total pollen abundance, because CFS percentages can be sensitive to fluctuations in pollen influx. In this work, we quantify the uncertainty associated with estimating concentration values at different total counts and find that high uncertainty is associated with concentration estimates using low to moderate total counts (n = 20 to 200) of individual fungal spore types and tracers. We also demonstrate the effect of varying tracer proportions, and find that larger tracer proportions result in narrower confidence intervals. Finally, the probability of encountering a CFS spore from a specific taxon occurring in moderate concentrations (1,000 spores/unit2) dramatically decreases after a low tracer count (∼50). The uncertainties in concentration estimates caused by calculating tracer proportion are a likely cause of the high observed variance in many CFS time series, especially when CFS or tracer concentrations are low. Thus, we recommend future CFS studies increase counts and report the uncertainty surrounding concentration values. For some records, reporting spore data as presence/absence rather than concentrations or counts is preferable, such as when performing high counts is not feasible.Fil: Perrotti, Angelina G.. University Brown; Estados UnidosFil: Ramiadantsoa, Tanjona. University of Wisconsin; Estados UnidosFil: OKeefe, Jennifer. Morehead State University; Estados UnidosFil: Nuñez Otaño, Noelia Betiana. Universidad Autónoma de Entre Ríos. Facultad de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Sediment Cores from White Pond, South Carolina, contain a Platinum Anomaly, Pyrogenic Carbon Peak, and Coprophilous Spore Decline at 12.8 ka

A widespread platinum (Pt) anomaly was recently documented in Greenland ice and 11 North American sedimentary sequences at the onset of the Younger Dryas (YD) event (~12,800 cal yr BP), consistent with the YD Impact Hypothesis. We report high-resolution analyses of a 1-meter section of a lake core from White Pond, South Carolina, USA. After developing a Bayesian age-depth model that brackets the late Pleistocene through early Holocene, we analyzed and quantified the following: (1) Pt and palladium (Pd) abundance, (2) geochemistry of 58 elements, (3) coprophilous spores, (4) sedimentary organic matter (OC and sedaDNA), (5) stable isotopes of C (δ13C) and N (δ15N), (6) soot, (7) aciniform carbon, (8) cryptotephra, (9) mercury (Hg), and (10) magnetic susceptibility. We identified large Pt and Pt/Pd anomalies within a 2-cm section dated to the YD onset (12,785 ± 58 cal yr BP). These anomalies precede a decline in coprophilous spores and correlate with an abrupt peak in soot and C/OC ratios, indicative of large-scale regional biomass burning. We also observed a relatively large excursion in δ15N values, indicating rapid climatic and environmental/hydrological changes at the YD onset. Our results are consistent with the YD Impact Hypothesis and impact-related environmental and ecological changes

Palynological Evidence for Terminal Pleistocene Paleoenvironmental Change at Two Sites in the Southeastern United States

Researchers interested in late-Pleistocene extinctions continue to debate the potential drivers of this event and, at times, do not even agree on the timing of extinction for various species in different regions. This dissertation presents two studies of the timing of megaherbivore disappearance and the effects of this process on local vegetation at two sites in the southeastern United States. This research uses two relatively novel methods that required extensive exploration and testing. Chapter II highlights an effective method for the removal of tiny, unwanted organic material from pollen samples. This method, sonication-assisted sieving, proved useful for eliminating such debris from organic-rich sediments. Chapter III describes the opportunities and limitations of using dung fungal spores as a proxy for herbivore abundance and extinction. Sustained interest in the timing of megaherbivore extinction in regions with poor organic preservation has led to a rapid increase in the use of dung fungi as a proxy for large herbivore abundance in archaeology and paleoecology. This chapter synthesizes modern mycological literature and suggests that there are many factors involved in the formation of a dung fungal spore record. Chapter IV presents the results of a palynological study of terminal Pleistocene sediments in two cores from the Page-Ladson archaeological site, Florida. The disappearance of Sporormiella, a proxy for megaherbivore abundance, by ~12,700 cal BP is consistent with the timing of terminal Pleistocene megafaunal extinction elsewhere in North America. Pollen evidence from the site also reflects dramatic vegetation changes, which are likely a response to both changing climate and fluctuating herbivore populations. Chapter V demonstrates the utility of fungal spores as paleoenvironmental proxies at White Pond, South Carolina. White Pond is a small pond located at the intersection of the Coastal Plain and the Piedmont in the southeastern United States. The data from White Pond also has implications for understanding the best application of dung fungal spore data as a proxy for large herbivore abundance. Overall, this dissertation research reflects the utility of applying innovative methods to palynology and archaeology

New Outlooks in Paleothnobotany: Review of Method and Theory in Paleoethnobotany by John M. Marston, Jade d’Alpoim Guedes & Christina Warinner (eds)

A review ofMethod and Theory in Paleoethnobotany by John M. Marston, Jade d’Alpoim Guedes & Christina Warinner (eds) (University Press of Colorado, 2014

Palynological Evidence for Terminal Pleistocene Paleoenvironmental Change at Two Sites in the Southeastern United States

Researchers interested in late-Pleistocene extinctions continue to debate the potential drivers of this event and, at times, do not even agree on the timing of extinction for various species in different regions. This dissertation presents two studies of the timing of megaherbivore disappearance and the effects of this process on local vegetation at two sites in the southeastern United States. This research uses two relatively novel methods that required extensive exploration and testing. Chapter II highlights an effective method for the removal of tiny, unwanted organic material from pollen samples. This method, sonication-assisted sieving, proved useful for eliminating such debris from organic-rich sediments. Chapter III describes the opportunities and limitations of using dung fungal spores as a proxy for herbivore abundance and extinction. Sustained interest in the timing of megaherbivore extinction in regions with poor organic preservation has led to a rapid increase in the use of dung fungi as a proxy for large herbivore abundance in archaeology and paleoecology. This chapter synthesizes modern mycological literature and suggests that there are many factors involved in the formation of a dung fungal spore record. Chapter IV presents the results of a palynological study of terminal Pleistocene sediments in two cores from the Page-Ladson archaeological site, Florida. The disappearance of Sporormiella, a proxy for megaherbivore abundance, by ~12,700 cal BP is consistent with the timing of terminal Pleistocene megafaunal extinction elsewhere in North America. Pollen evidence from the site also reflects dramatic vegetation changes, which are likely a response to both changing climate and fluctuating herbivore populations. Chapter V demonstrates the utility of fungal spores as paleoenvironmental proxies at White Pond, South Carolina. White Pond is a small pond located at the intersection of the Coastal Plain and the Piedmont in the southeastern United States. The data from White Pond also has implications for understanding the best application of dung fungal spore data as a proxy for large herbivore abundance. Overall, this dissertation research reflects the utility of applying innovative methods to palynology and archaeology

Dung fungi as a proxy for megaherbivores: opportunities and limitations for archaeological applications

The use of spores of coprophilous fungi from sedimentary sequences as proxy evidence for large herbivore abundance has garnered pronounced attention and scrutiny over the past three decades. In response to the rapid rate at which new information is being discovered on this topic, this paper presents a brief review of the archaeological applications so far, and outlines opportunities and limitations of using Sporormiella as a proxy for herbivore abundance. Specific archaeological uses of this proxy include understanding megaherbivore extinctions and human land use patterns such as pastoralism and agriculture. We analyse how dung fungal records are formed and review the mycological literature to outline factors affecting spore reproduction and preservation. These include how strongly each commonly used dung fungal taxon relies on dung as a substrate and environmental factors affecting dung fungal reproduction and coprophilous fungi deposition. Certain laboratory preparation techniques adversely affect spore representation on pollen slides. The methods of analysis and quantification of spore records also impact our understanding. We describe good practice to increase precision of analytical methods. Due to limitations imposed by some of these factors, it is possible that an absence of dung fungi from a palaeoecological record does not imply an absence of herbivores. However, consideration of these factors and inclusion of as wide a range of coprophilous spore records as possible increases the reliability of such inferences

Coprophilous fungal spores: non-pollen palynomorphs for the study of past megaherbivores

Spores from coprophilous fungi are some of the most widely used non-pollen palynomorphs. Over the last decades, these spores have become increasingly important as a proxy to study the Pleistocene and Holocene megafauna. Although the number of types used in palaeoecology is relatively small, there is a wide range of coprophilous fungal taxa whose utility in palaeoenvironmental reconstruction remains under-researched. However, environmental and taphonomic factors influencing preservation and recovery of these spores are still poorly understood. Furthermore, our understanding of whether and how spores are transported across the landscape is limited. Dung fungal spore presence appears to correlate well with megaherbivore presence. However, depending on the site, some limitations can remain to quantitative reconstructions of megaherbivore abundance from dung fungal spore records. The presence of dung fungal spores is often more significant than their absence and variation in abundance with time should be interpreted with caution. Correlation with other proxies may provide a promising way forward. The majority of studies using dung fungal spores as an indicator for large herbivore abundance are of records of Late Pleistocene and Holocene age, with a focus on Late Quaternary megafaunal extinction. However, more research could potentially extend records further back in time