Photo: Excavation site at Albas, Massif des Corbières (France) © Gaëtan Rochez (UNamur)

Current predictions for biodiversity evolution in the face of climate change are based on models and scenarios derived from multidisciplinary studies. An article has just been published in the prestigious journal PNAS (Proceedings of the National Academy of Sciences), feeding into these scenarios. The researchers' original idea? To envisage an analogy between the biodiversity of the past and that of the future.

To understand, we need to go back 56 million years, to the transition between the Paleocene and the Eocene, a period characterized by intense global warming (named Paleocene-Eocene Thermal Maximum - or PETM). Paleoclimatologists consider this period to be a geological analogue of today's warming in terms of its amplitude (an increase of 5 to 8°C) and cause (a massive release of CO₂ into the atmosphere, similar to what we experience today).

At this time, global warming generated major disturbances on fauna. This change in climate, although 10 to 100 times slower than the one we experience today, coincided with the appearance of "modern" placental mammals (of which humans are a part), but also artiodactyls (ruminants, goats...), perissodactyls (horses, rhinoceroses...), bats, rodents and so on. Intense and rapid climatic disturbances generate major stresses on ecosystems: organisms try to adapt, some disappearing because they are unable to cope with these intense environmental changes, while others develop or evolve. This scenario was already well known...

But a few thousand years before PETM, another warming episode, named Pre-Onset Event (or POE), is recorded. It is less intense (+2°C) than the PETM, and more similar to current climate disturbances, leading researchers to investigate its impacts on faunas.

Photo: In search of fossils by fellow paleontologists from the University of Montpellier © ISEM

Field research has been carried out in the Massif des Corbières, southern France: the geological layers representative of this period are numerous and thick. Thanks to carbon isotope geochemistry, Namur researchers have been able to date these layers with great precision, making it possible to detail the evolution of fossils over time.

The fossils thus discovered have delivered their memory. And this calls into question previously established scenarios on two key aspects:

• Species evolved rapidly as early as the EOP, a climatic event similar to today's disturbances.
• While researchers thought that European faunas were composed of species endemic to Europe, they discovered that these archaic animals also rubbed shoulders with more modern species, such as marsupials or rodents, having probably migrated from North America during the EOP.

Photo: Mammal fossils discovered at Albas preserved in small glass tubes. These are the tiny teeth of a small "archaic" mammal called Paschatherium. Rodolphe Tabuce

So, during the EOP, species migrated from one continent to another... But how is this possible? It was thought that, at the time, the European continent was relatively isolated from the others by shallow seas. In reality, as a result of global warming, vast expanses of forest covered the high latitudes (present-day northern Greenland, Scandinavia and the Bering Strait in Siberia), serving as "natural land bridges" for forest fauna! Climatic disturbances therefore modified the flora, which in turn served as a passage between continents for "modern" faunas, also in the midst of upheaval.

The climatic disturbances of the POE, similar to those recorded today, therefore drastically influenced the faunas, notably by facilitating intercontinental migrations.

The impact of these decisive events during the EOP offers new avenues for reflection and study on the future of biodiversity in the context of current and future global warming.

"EDENs: Life during past super-warm climate events: Evolutionary Dynamics of Early EoceNe mammals from Southwestern France" is a multidisciplinary and international project in which Johan Yans, Jean-Yves Storme and Gaëtan Rochez (Department of Geology and ILEE Institute at UNamur) have been involved for the past 3 years. This research brings together the expertise of various partners:

• L'Institut des Sciences de l'Evolution de Montpellier (ISEM), Rodolphe Tabuce and Fabrice Lihoreau,
• Géosciences Montpellier, Flavia Girard and Gregory Ballas.

It is funded by the Agence Nationale de la Recherche (ANR-France). Its mission is to support and promote the development of fundamental and finalized research in all disciplines, and to strengthen the dialogue between science and society.

• Climate warming 56 million years ago: can biodiversity from the past help us anticipate the future? - The Conversation
• Climate warming: can biodiversity from the past help us? - RTBF

In terms of training, in addition to courses incorporating the SDOs, the University of Namur offers the University Certificate of Further Training in Sustainable Development. Aimed at members of organizations, administrations, companies, schools, etc. concerned or simply interested in the implications and challenges of sustainable development, it aims to offer information that is as thoughtful and diversified as possible, in order to help each participant better position, in his or her professional context, the issues linked to sustainable development that concern him or her more directly.

In terms of research, researchers work through 11 interdisciplinary research institutes. Johan Yans' team is active within the Institute ILEE - Institute of Life, Earth and Environment - and this research is a focus of activities devoted to Sustainable Development at UNamur.

In 2021, Professor Frédérik De Laender was approached by American researchers to contribute to a study on the evolution of aquatic diversity in rivers in the USA. The aim: to analyze changes in aquatic diversity and identify the factors behind them. To answer this question, the researchers analyzed data collected over thirty years, covering 389 fish species in nearly 3,000 rivers and streams.

"There was already a lot of data on aquatic diversity in the USA, but it was scattered, recorded in different formats and produced using a variety of techniques and methodologies," explains Frédérik De Laender. "The challenge was therefore to harmonize them, in order to form a coherent whole, capable of revealing trends over several decades and on a continental scale."

In this study entitled "Diverging fish biodiversity trends in cold and warm rivers and streams" researchers studied 389 fish species in 2,992 rivers and streams, between 1993 and 2019. The results show contrasting trends depending on water temperature:

• In cold waters (< 15.4°C), the number of fish fell by 53% and the number of species by 32%. Small fish have declined, replaced by larger species often introduced for sport fishing.
• In warm waters (> 23.8°C), by contrast, the number of individuals has increased by 70% and diversity by 16%, with small opportunistic species dominating.
• Intermediate streams (15-24°C) showed little change.

These trends show that temperature changes and the introduction of certain fish species for fishing are helping to transform local aquatic communities.

Frédérik De Laender is a theoretical community ecologist who studies the links between environmental change, biodiversity and ecosystem functioning. Primarily focused on modeling, he has also conducted experiments on plankton and contributed to meta-analyses. His work focuses in particular on ecological stability and coexistence, to better understand the mechanisms that determine community composition.

The beluga whale (Delphinapterus leucas) of the St. Lawrence Estuary (SLE) in Quebec, Canada, lives in a marine ecosystem heavily impacted by human activities and has shown no signs of recovery for several decades. Also known as the white whale or white dolphin, the beluga has a life expectancy of around 70 years. Infectious diseases and an increase in post-partum mortality in females have been observed, but the exact causes remain undetermined. However, exposure to contaminants is thought to be one of the causes of the increase in early mortality observed in recent years.

One of the main limitations to assessing the health of individuals in this population in relation to contaminant exposure is the lack of a method for determining the age of live beluga whales in the ESL.

Until now, the most reliable method for determining their age was to count the growth streaks on the inside of their teeth. The expertise of Namur-based researchers at Professor Frédéric Silvestre's Laboratoire de Physiologie Évolutive et Adaptative (LEAP) will enable the development of a new "epigenetic clock" and its use to estimate the age of living belugas, ultimately improving conservation strategies to help this threatened population recover.

The project is entitled: "Une horloge épigénétique pour estimer l'âge des belugas du Saint-Laurent et son impact sur l'accumulation de contaminants, le stress et la santé de cette population menacée"

Epigenetics is the study of changes in gene activity, not involving modification of the DNA sequence, that can be transmitted during cell divisions. One of the elements that "regulate" gene expression is methylation: a chemical group that attaches itself to certain places on the DNA strand to promote or limit gene expression. In recent decades, it has been discovered that methylation changes in a predictable way during aging, according to a pattern known as the "epigenetic clock". Once this clock has been established for a given population of individuals, it is therefore possible to deduce an individual's age by looking for the presence or absence of methylation on DNA. All it takes is a few cells, such as skin cells.

A team of top scientists from both regions is involved.

• Pr Frédéric Silvestre and Dr Alice Dennis - UNamur, Belgium
• Dr Krishna Das - ULiège, Belgium
• Dr Jonathan Verreault - Université du Québec à Montréal, Canada
• Dr Stéphane Lair - Université de Montréal, Canada
• Dr Magali Houde - Environment and Climate Change Canada
• Dr Véronique Lesage - Fisheries and Oceans Canada
• Dr Robert Michaud - Group for Research and Education on Marine Mammals (GREMM), Quebec, Canada

The research team will validate this new method and investigate the link with contaminant accumulation, physiological stress and overall health in this threatened population, comparing the ESL population with a healthier population of belugas from the Canadian Arctic.

In summary, this research aims to better understand how biological age, as measured by the epigenetic clock, influences the vulnerability of belugas to environmental stressors and their health.

This project will address fundamental research questions never before explored in beluga whales,

A new PhD student will join the Namur team, under the supervision of Frédéric Silvestre and will work in collaboration with researcher Justine Bélik on the basis of the EpiClock she developed for the mangrove rivulus.

Along with a project on mangrove rivulus in Florida and Belize, and one on fish and invertebrate populations in the Ecuadorian mountains, this is the third scientific project to use Namur researchers' expertise in ecological epigenetics in wild animals to help preserve biodiversity.

Collaborative research F.R.S.-FNRS - FRQ (Fédération Wallonie-Bruxelles - Québec)

The F.R.S.-FNRS has launched PINT-Bilat-P calls for bilateral research projects with the Fonds de Recherche du Québec. These calls are part of a drive to develop strategic partnerships. The aim of this bilateral research program is to create a leverage effect for scientific excellence and to encourage researchers from the Wallonia-Brussels Federation and Quebec to develop innovative joint research projects.

• Long-term effects of pollution in our rivers, oceans and lakes
• Understanding epigenetics to conserve biodiversity

In recent months, the commune of Gesves, in the province of Namur, was confronted with the presence of a herd of mouflons, wild sheep recognizable by their impressive spiral horns. At the origin of this one: a male and a female probably escaped from a private hunt, who settled and reproduced in the meadows of this rural commune in 2019, until forming a full-fledged herd of 17 individuals in 2024.

While these sheep won the affection of the locals, local farmers deplored the damage caused to their crops. Their complaints led in August 2024 to a destruction authorization from the Department of Nature and Forestry (DNF). Several individuals were also shot during the hunting season.

Touched by the fate of these animals, a handful of local residents have been carrying out a veritable rescue operation for the seven mouflons still present on the meadows since January. The maneuver promised to be complex, to say the least: on the one hand, it was necessary to gather the official authorizations required to capture and transport the mouflons to a suitable location, and on the other hand, to set up an infrastructure to capture them.

Alongside this initiative, the mobilized local residents - including Nathalie Kirschvink, a veterinarian and professor at UNamur's Faculty of Medicine - called on the expertise of the laboratories of UNamur's Environmental and Evolutionary Biology Research Unit (URBE) to clarify a crucial question: the origin of the mouflons. Indeed, in our regions, mouflons are considered game and therefore huntable, while mouflons from certain lineages benefit from protection.

Nathalie Kirschvink therefore entrusted fresh samples made up of hair and dung to Alice Dennis, professor and researcher at the URBE. Sequencing the DNA contained in these samples enabled Alice Dennis and technician Jérôme Lambert to identify kinship links between the Gesves bighorn sheep and those from a Corsican lineage, whose genome had already been described in the scientific literature.

This expertise lies at the heart of URBE's research, which uses the tools of molecular ecology to study both the physiology of organisms (such as snails for Alice Dennis) and their interactions with their environment. The methodology used can be applied to very concrete, local cases, such as that of the Gesves bighorn sheep, but, more broadly, serve to better understand genetic diversity between species with a view to safeguarding biodiversity.