How can fossil data be used to inform conservation decisions, and how do ecometrics contribute?
The majority of environmental challenges faced by conservationists contemporarily, have precedents in the past. Importantly, the fossil-record and associated long-term-environmental archives can provide unique insights towards the resolution of these challenges, especially concerned with understanding ecosystems prior to anthropogenic impacts; insights which have spurred the use of Paleobiology in conservation. Fossil data contributes to the biggest conservation questions including:
i) What should be conserved?
ii) Identification of species at risk
iii) Identification of thresholds
Underlying all of these conservation issues is the goal of enhancing adaptive capacities of ecosystems, increasing connectedness and improving functional integrity. These goals require a functional understanding of ecosystems, which can be achieved using ecometric analyses, this is a taxon-free trait-analysis studying the distribution of functional traits, and the environmental sorting of those traits, enabling predictions for the future based on current changes. I argue that perhaps the most important aspect shown by the fossil record is how novel modern ecosystems are; species are under pressure from a unique combination of threats not replicated in the historical-record, and in this regard, responses are somewhat unknown. This considered, conservation decisions should reflect the fact that we should not be trying to replicate historical conditions, but instead, with the use of ecometric-knowledge we should create functionally-intact novel ecosystems.
i) What should be conserved?
A major way in which the fossil-record can be used to inform conservation decisions is by providing evidence to indicate whether conservation should aim towards creating ‘novel’ or ‘historical’-systems. Historical-ecosystems are those which are operating as they have for centuries compared to novel eco-systems which are new in the ‘Anthropocene’. In order to decide the state an area should be conserved in, fossil data is used; this involves taxon-based (involving comparisons of taxa presence) and taxon-free (reflecting ecosystem function)-measures. Taxon-based-studies comprise of superimposed, well-dated fossils to produce snapshots of the past, allowing data on abundance and species-fluctuation to be analysed. One example where this is used was the re-introduction of wolves into Yellowstone; fossil-evidence showed that wolves had inhabited the region for>3000 years, this was given additional climate-context through pollen-studies, which indicated that the local climate had not changed significantly for>8,000 years. These findings supported the conservation of the area in its historical-state; leading to the successful re-introduction of wolves.
The alternative conservation decision; creation of a novel-systems, is also informed by fossil data. This is exemplified by the conservation strategy to protect Joshua trees in California. Fossil evidence in the form of Shashta-ground-sloth dung has shown that the tree is historically sensitive to increases in temperature. Given both the projected climate-change in the region as well the extinction of the ground sloth, its main seed disperser, the tree would is projected to go extinct in the region by 2070 without conservation action (Sweet et al 2019). These findings led to the conservation decision that a more active-management strategy is required. In this way, fossil data has led to effective conservation decisions.
In novel ecosystems, ecometric-analyses are often more applicable due to taxon-free metrics relating to environmental parameters with a degree of statistical-significance. This provides an opportunity for modelling the type of species which are likely to thrive in a region. This has been done on a large scale by Svenning-et-al-2017; this study models historical megafaunal distributions and compares these to modern climactic conditions to create a map where introductions of megafauna including mammoths, horses and hippo species could be re-introduced. Advances on these models include the suggestion of functionally-similar species to mammoth in the UK considering that mammoths went extinct ~14,000ya regionally; Monbiot has argued in numerous papers for the benefits that would confer to the habitat, including nitrogen turnover and positive impacts for agriculturally important insects. These somewhat drastic suggestions are supported by ecometric data which shows that the tooth of the elephant is compatible with the foliage in the remaining wild forests of the UK, and their temperature thresholds are similarly compatible (Ukkonen-et-al-2011). These re-wilding-conservation-projects currently rely on climactic parameters alone to estimate niche space; paleontologically-enhanced species-distribution-models would be helpful for the relocation or introduction of species into suitable-environments.
Given the unique and intensifying threats to modern ecosystems, novel ecosystems are likely to become more important as a conservation strategy; ecometrics should therefore be increasingly used to inform how these novel-ecosystems can be made to be functionally-intact and sustainable using historical-information. This is especially relevant in the land-sharing/ land-sparing-debate. Considering the combined impacts of increasing population and food demand, it is estimated that without significant yield intensification cropland will require an additional 600million hectares by 2050. This is relevant to this discussion because, in line with these predictions, policy changes starting in the UK with the environmental-Bill and suggestions from IPCC-reports, (promoting land-sparing strategies in agriculture), there will be increasing land-use-mapping which are expected to segregate land-uses more extensively; limiting regions for wild-life further. Ultimately, an earth split between a)agriculture b)urban-landscapes and c)wildlife/carbon-storage is what these policies seem to be moving towards. If this vision is realised, conservationists will be asked to protect as much biodiversity as possible in limited-regions; the resulting-collections of species may be entirely unique, yet functionally-sound if ecometric-models and historical-data are well collated. Although radical, these anthropocentric factors must be taken into account. Ecometrics and insights from fossil-data have the potential to make these drastic conservation decisions better informed and more likely to succeed.
ii) Identification of species at risk
In addition to contributing to conservation decisions on the state being conserved, fossil evidence informs conservation decisions at a species-level; identifying species traits which predict their survival in changing conditions. One example of this is data on mass-extinctions during the Permian-Triassic transition, where feed-back-loops from trap-volcanoes caused CO2 levels to rise similarly to current conditions. Fossil analysis coupled with biochemical knowledge indicates that the CO2 tolerant species were much more likely to survive this period than CO2-intolerant species- with a 38%-extinction compared to 81%-extinction in CO2-intolerant (Knoll-et-al-1996). This fossil information can be extrapolated to present conditions, predicting higher survival-potential for CO2-tolerant-species; perhaps indicating that more conservation action should be focussed on protecting CO2-intolerant-species. These functional-trait based analyses show the relevance of ecometrics to current-conservation challenges.
An emerging area of ecometrics is the study of historical-symbiotic-interactions and their responses to climate-change. Pither-et-al-(2018) study an ice-core containing evidence of the nitrogen-fixing-ectomycorrhizal-fungi and associated flora in New-Zealand. This eDNA-fossil analysis studied the interaction over 50,000years in relation to climactic changes. The study concludes that the symbiotic-relationship was negatively impacted by increased-temperatures. This aligns with Steidinger-et-al-2019, where the historical-symbiotic relationships’ interaction with climate is considered in the context of current-climate-change; the model suggests that changes in the Northern-Hemisphere could displace ectomycorrhizal-fungi to other regions, leading to a potential 60%reduction in the density of dependent trees. These outcomes would affect nutrient cycling and carbon fixation significantly and should be considered in carbon-based conservation initiatives. Identification of these relationships at risk using ecometric data can therefore guide conservation decisions by demonstrating potential threats to ecosystem-functioning.
Fossil evidence is imperative in niche-modelling to analyse the adaptive-capacity for individual species or populations. The adaptive-capacity of a species will determine the conservation strategy used; using fossil-data to discern the fundamental-niche of a species can indicate the adaptive-capacity of the species. One example of niche modelling compares the fundamental and realized niche of the three toes sloth (Philips-et-al-2017). This study produces MAXENT-models based on BIOCLIM-19-parameters. The results limited to modern-data could be expanded using hindcasting-techniques as current niches may not represent the total ecological-flexibility of taxa. McGuire-and-Davis-(2013) show how hindcasting using fossil-data can expand on knowledge using only modern-data; distribution-information from fossils of five-Microtus-species in the United-States were projected onto alternative-climate-surfaces, finding that the range of these species has undergone significant contraction since the last-glacial-maximum, and their predicted range tolerance is much larger than current-data would suggest. Accordingly, fossil-based niche-analysis can better inform adaptive-capacities, helping to identify species which should be conservation priorities.
iii) Identification of thresholds
On a wider scale to these niche-level applications, fossil and ecometric data are pivotal in the determination of environmental-tipping-points. Mathematical comparisons between fossils in lake-sediments, diatoms/pollen from Yunnan in China and regional ecological state shifts indicates strong correlations. In light of these results, it is clear to see how inter-disciplinary modelling projects which use paleobiological/ fossil/ecometric data to supplement climate and agricultural models could contribute to understanding the potential for anthropogenic refugia, for a more holistic conservation approach.
Fossil-data is a versatile and valuable component in the conservation tool-box. It contributes to conservation decisions about the state that a system should be conserved in, informing re-wilding efforts, making radical conservation-actions less-risky, informing natural-base-lines, identifying species and relationships vulnerable to environmental-changes, and understanding environmental-tipping-points. Coupled with ecometrics which provides functional-information for conservation and is especially relevant in the conservation efforts in novel-ecosystems, these paleontological methods are critical to effective and sustainable conservation action. Certain limitations exist such as the methods being less available for are species restricted to areas of low fossilisation potential. Nevertheless, the data has and will continue to be instrumental in global conservation-efforts.
