Micro Methods for Megafauna: Novel Approaches to Late Quaternary Extinctions and Their Contributions to Faunal Conservation in the Anthropocene

Abstract

Drivers of Late Quaternary megafaunal extinctions are relevant to modern conservation policy in a world of growing human population density, climate change, and faunal decline. Traditional debates tend toward global solutions, blaming either dramatic climate change or dispersals of Homo sapiens to new regions. Inherent limitations to archaeological and paleontological data sets often require reliance on scant, poorly resolved lines of evidence. However, recent developments in scientific technologies allow for more local, context-specific approaches. In the present article, we highlight how developments in five such methodologies (radiocarbon approaches, stable isotope analysis, ancient DNA, ancient proteomics, microscopy) have helped drive detailed analysis of specific megafaunal species, their particular ecological settings, and responses to new competitors or predators, climate change, and other external phenomena. The detailed case studies of faunal community composition, extinction chronologies, and demographic trends enabled by these methods examine megafaunal extinctions at scales appropriate for practical understanding of threats against particular species in their habitats today.

Collapse of the mammoth-steppe in central Yukon as revealed by ancient environmental DNA

“…Much of the LQE debate has been limited by the inability of dated macrofossils (primarily from detrital contexts) to convey the spatio-temporal resolution necessary to untangle the causative versus correlative ecological transformations associated with the Pleistocene-Holocene transition. Molecular (micro) methods 69 are increasingly able to augment discontinuous macrofossil records. This can aid in identifying cryptic populations (or ghost ranges) 37,70,71 , independently assess population declines, and estimate the timings of functional extinctions/extripations 15,72 -the point at which undercrowding and inbreeding depression lead to a loss of fitness through Allee effects [73][74][75] to the degree that a species no longer significantly contributes to ecosystem functioning, becoming a trace presence in records before completely disappearing.…”

Tracking Hunter-Gatherer Impact on Vegetation in Last Interglacial and Holocene Europe: Proxies and Challenges

“…Stable carbon, oxygen and strontium isotope data are used in studies of megafaunal mobility, their geographic range and anthropogenic and climatic factors influencing animals (Swift et al, 2019). Geographically and temporally different populations and subpopulations have distinct isotopic values (Hoppe, 2004;Price et al, 2017).…”

Bone need not remain an elephant in the room for radiocarbon dating

“…14 C dating has meritoriously established itself as one of the most powerful tools for dating cultural and palaeontological deposits from the late Quaternary [ 3 , 56 ]. The method is conceptually simple and well understood (see Introduction).…”

“…C age discrepancies obtained from gelatin of the same fossil bone with and without these additional pretreatment steps range from hundreds to thousands of years [53][54][55][56][57][58][59][60][61][62][63]. These discrepancies can lead to starkly contrasting conclusions about the demographic and genetic history of species including domestication, invasion and extinction events, and placement within discrete climate events, and, therefore, deserve careful consideration [2,64].…”