Research
My research lies at the interface of conservation biogeography, historical ecology and restoration, with a particular focus on understanding the long-term patterns of distribution and abundance of large mammals to inform their management and restoration. My previous research activities have involved a diverse research program, applying statistical and spatial modelling approaches on biodiversity data from diverse sources – including deep-time fossil records, historical accounts, modern ecological data and spatialized earth system data – to investigate these questions, focusing on three main objectives: 1) To understand the long-term changes in species distribution and abundance as a result of anthropogenic impacts, 2) To improve the use of long-term biodiversity data in ecological and conservation analyses and 3) To identify options for the conservation and restoration of threatened mammalian species in the Anthropocene.
Main research projects:
Using recent baselines as benchmarks for megafauna restoration places an unfair burden on the Global South
The potential for megafauna restoration is unevenly distributed across the world, along with the socio-political capacity of countries to support these restoration initiatives. We show that choosing a recent baseline to identify species' indigenous range puts a higher burden for megafauna restoration on countries in the Global South, which also have less capacity to support these restoration initiatives. We introduce the Megafauna Index, which considers large mammal's potential species richness and range area at the country level, to explore how the responsibility for megafauna restoration is distributed across the world according to four scenarios using various temporal benchmarks to define species' indigenous range – current, historical (1500 AD), mid-Holocene and Pleistocene. We test how the distribution of restoration burden across the world correlates with indicators of conservation funding, human development and governance. Using a recent or historical baseline as a benchmark for restoration puts a higher pressure on African and south-east Asian countries while lifting the responsibility from the Global North, where extinctions happened a long time ago. When using a mid-Holocene or Pleistocene baseline, new opportunities arise for megafauna restoration in Europe and North America, respectively, where countries have a higher financial and societal capacity to support megafauna restoration. These results contribute to the debate around benchmarks in rewilding initiatives and the ethical implications of using recent baselines to guide restoration efforts. We suggest that countries from the Global North should reflect on their responsibility in supporting global restoration efforts, by both increasing their support for capacity building in the Global South and taking responsibility for restoring lost megafauna at home. https://doi.org/10.1111/ecog.05795
Anthropocene refugia: integrating history and predictive modelling to assess the space available for biodiversity in a human-dominated world
During periods of strong environmental change, some areas may serve as refugia, where components of biodiversity can find protection, persist and potentially expand from should conditions again become favourable. The refugia concept has previously been used in the context of climatic change, to describe climatically stable areas in which taxa survived past Quaternary glacial-interglacial oscillations, or where they might persist in the future under anthropogenic climate change. However, with the recognition that Earth has entered the Anthropocene, an era in which human activities are the dominant driving force on ecosystems, it is critical to also consider human pressures on the environment as factors limiting species distributions. Here, we present a novel concept, Anthropocene refugia, to refer to areas that provide spatial and temporal protection from human activities and that will remain suitable for a given taxonomic unit in the long-term. It integrates a deep-time perspective on species biogeography that provides information on the natural rather than current-day relictual distribution of species, with spatial information on modern and future anthropogenic threats. We define the concept and propose a methodology to effectively identify and map realised and potential current and future refugia, using examples for two megafauna species as a proof of concept. We argue that identifying Anthropocene refugia will improve biodiversity conservation and restoration by allowing better prediction of key areas for conservation and potential for re-expansions today and in the future. More generally, it forms a new conceptual framework to assess and manage the impact of anthropogenic activities on past, current and future patterns of species distributions.
Monsarrat S., Jarvie S., Svenning J-C. (2019) Anthropocene refugia: integrating history and predictive modelling to assess the space available for biodiversity in a human-dominated world. Philosophical Transactions of the Royal Society B (doi: 10.1098/rstb.2019.0219)
Reconstructing historical baselines for southern African terrestrial mammals to inform conservation management
Humans have driven biodiversity loss and modified ecosystem structure for millennia. Using modern ecological data to reconstruct anthropogenic impacts on biodiversity therefore has the risk of considerably underestimating the full scale of human-caused extinctions through time. This bias affects our understanding of ecological patterns of “natural” species distributions and abundance and of the dynamics and drivers of past extinctions, and ultimately narrows our perception of the options available for conservation and management. Long-term archives are often perceived as unsuitable for ecological analyses because of the substantial levels of spatial and temporal bias and error they may contain. However, by extending the timeline usually considered in ecology, they can provide unique new insights into extinction dynamics and changing species status through time and represent a unique opportunity to better inform regional environmental management. Assessment and utilization of historical data thus represent both a methodological challenge and an important conservation research priority.
Southern Africa is a region of global conservation importance, where large terrestrial mammals have been highly impacted by humans’ activities, especially since the start of the colonial period. Consequently, local, regional or global extinctions have occurred for several species in this area over the past centuries without ever being comprehensively recorded or studied. Professor Graham Kerley and his historical ecology research group at the Centre for African Conservation Ecology, have compiled a large dataset of past distribution records for medium- to large-sized terrestrial mammals in South Africa, during the early historical period (late 1400 s to the 1920s). I completed this dataset with zooarchaeological and modern occurrence records, to obtain the most comprehensive and up-to-date database of large mammal distribution records from the early Holocene to the present throughout South Africa.
Taxonomic bias
These long term records are strongly biased in terms of the species represented. We identified a strong taxonomic bias, with up to several order of magnitudes of difference in the likelihood of reporting between some species. Species' charisma alone explains 75% of the observed variance, the most charismatic species being largely over-reported. This is the first evidence of a positive relationship between taxonomic bias and charisma in a historical biodiversity dataset, within a homogeneous taxonomic group such as large terrestrial mammals. These results improve our understanding of the relationship between people and the large terrestrial fauna in historical times and suggest that species' charisma is a good predictor of taxonomic bias in long-term biodiversity datasets. This provides background for modern conservation by illustrating the durability of the charisma concept and of its relation with taxonomic bias, with implications for the representativeness of species in long-term conservation studies.
See the publication: Monsarrat S., G.I.H. Kerley. (2018) Charismatic species of the past: biases in reporting of large mammals in historical written sources. Biological Conservation: 223, 68-75. https://doi.org/10.1016/j.biocon.2018.04.036
Spatial and environmental bias
The collection process for biodiversity records is often spatially biased towards regions more frequented by observers. This results in observed distribution patterns that are a reflection of the intensity of sampling rather than of the actual distribution of species. We found a preference for lower maximum temperature of the warmest month, higher mean monthly precipitation, higher net primary productivity and less arid biomes than expected by a uniform use of the study area. Accessibility maps based on simple statistical rules and only two spatial features could predict the geographical and environmental bias found in the South African dataset. These results suggest that sampling effort can be modelled accurately without the use of empirical data, given that we know the processes influencing the bias behind data collection. We suggest that, rather than discarding historical occurrence datasets a priori due to the possible biases they may contain, accessibility maps could be used to explore sampling bias and improve the use of these data in modern quantitative analyses.
Monsarrat S., A. Boshoff, G.I.H. Kerley. (2018) Accessibility maps as a tool to predict sampling density in historical biodiversity occurrence records. Ecography doi:10.1111/ecog.03944
Shifted distribution baselines
We tested whether neglecting long-term occurrence records leads to an underestimation of species’ historical niche and potential distribution and identify which species are more vulnerable to this effect. We compare outputs of species distribution models and niche hypervolumes built using recent records only with those built using both recent and long-term (post-1500) records, for a set of 34 large mammal species in South Africa. We find that, while using recent records only is adequate for some species, adding historical records in the analyses impacts estimates of the niche and habitat suitability for fourteen species (41%) in our dataset, and that this effect is significantly higher for carnivores. These results show that neglecting long-term biodiversity records in spatial analyses risks misunderstanding, and generally underestimating, species’ niche, which in turn may lead to ill-informed management decisions, with significant implications for the effectiveness of conservation efforts.
Monsarrat S., Novellie P., Rushworth I., Kerley G.I.H. (2019) Shifted distribution baselines: neglecting long-term biodiversity records risks overlooking potentially suitable habitat for conservation management. Philosophical Transactions of the Royal Society B. (doi: 10.1098/rstb.2019.0215)
This project was funded by a postdoctoral fellowship from the Claude Leon Foundation.
Reconstruction of marine mammal’s historical distribution and abundance: setting a baseline to understand the past, inform the present and plan the future
Historical distribution and abundance of the Endangered North Atlantic right whale (Eubalaena glacialis)
In my PhD, I investigated the challenges and opportunities of combining historical data with analytical methods to improve historical baselines for marine mammals. Occurrence data from archaeological, historical and industrial sources were reviewed, revealing range contractions and population depletions from prehistorical times to today. For the highly depleted North Atlantic right whale, (Eubalaena glacialis), I obtained a detailed estimate of pre-whaling distribution and abundance by inferring from the historical distribution and abundance of its congeneric North Pacific right whale (E. japonica). These results suggest that the North Atlantic right whale occupies a small fraction of its historical range and that its current population represents <5% of its historical abundance, with implications for the management, monitoring and conservation targets of this species. More generally, this project emphasize the utility of considering historical data to understand the extent to which species have been impacted by humans, assess their current level of depletion, and inform the options available for their future recovery.
Monsarrat S., Smith T.D, Reeves R.R, Pennino M.G., Meynard C.M., Kaplan D.M., Rodrigues A.S.L. (2016) A spatially-explicit estimate of the pre-whaling abundance of the endangered North Atlantic right whale. Conservation Biology : 30(4), 783-791. doi:10.1111/cobi.12664
Monsarrat S., Smith T.D, Reeves R.R, Pennino M.G., Meynard C.M., Kaplan D.M., Rodrigues A.S.L (2015) Historical summer distribution of the endangered North Atlantic Right Whale (Eubalaena glacialis): a hypothesis based on the environmental niche of a congeneric species. Diversity and Distributions: 21(8), 925-937. doi: 10.1111/ddi.12314
Ancient whale exploitation in the Mediterranean
How did ancient communities around the Mediterranean exploit the presence of whales in their seas? Given that the whales currently present in the region are seldom found near the coast, it seems probable that ancient whale exploitation would have been restricted to stranded animals. We explore, however, the possibility that additional species migrated seasonally through the Strait of Gibraltar to visit coastal calving grounds, which could have supported an organised whaling industry. Classical literature provides a number of descriptions suggestive of coastal encounters with whales. New methods of whale bone identification will shed light on which species were previously present in the Mediterranean and thus on the probability of ancient whaling.
Rodrigues A.S.L, Kolska Horwitz L., Monsarrat S., Charpentier A. (2016) Ancient whale exploitation in the Mediterranean: species matters. Antiquity: 90 352: 928–938 https://doi.org/10.15184/aqy.2016.109
EPOCH - A framework to document cumulative anthropogenic impacts on populations
Ecological baselines—reference states of species' distributions and abundances—are key to the scientific arguments underpinning many conservation and management interventions, as well as to the public support to such interventions. Yet societal as well as scientific perceptions of these baselines are often based on ecosystems that have been deeply transformed by human actions. Despite increased awareness about the pervasiveness and implications of this shifting baseline syndrome, ongoing global assessments of the state of biodiversity do not take into account the long-term, cumulative, anthropogenic impacts on biodiversity. Here, we propose a new framework for documenting such impacts, by classifying populations according to the extent to which they deviate from a baseline in the absence of human actions. We apply this framework to the bowhead whale (Balaena mysticetus) to illustrate how it can be used to assess populations with different geographies and timelines of known or suspected impacts. Through other examples, we discuss how the framework can be applied to populations for which there is a wide diversity of existing knowledge, by making the best use of the available ecological, historical and archaeological data. Combined across multiple populations, this framework provides a standard for assessing cumulative anthropogenic impacts on biodiversity.
Rodrigues A.S.L., Monsarrat S., Charpentier A., Brooks T., Hoffmann, M., Reeves, R.R., Palomares M.L.D., Turvey, S.T. (2019) Unshifting the baseline: a framework for documenting historical population changes and assessing long-term anthropogenic impacts. Philosophical Transactions of the Royal Society B (doi: 10.1098/rstb.2019.0220)
This project was conducted as part of The MORSE project, funded by the French National Research Agency (Agence Nationale de la Recherche, ANR; call CEP&S 2011 - Project ANR-11-CEPL-006). It ran from November 2011 to October 2015. Check the website HERE.