Why has biodiversity decreased over the past 20 million years? Why did large mammals, such as giant sloths, tapirs, and mammoths, go extinct at the end of the last ice age, some 50,000 to 10,000 years ago? Why are there many fewer mammal species today than there “should be”?

In this episode, we speak with Prof. Susanne Fritz, research group head at iDiv and the Friedrich Schiller University Jena, about biodiversity change over very long time scales. She shares insights into how past extinction events shaped today’s ecosystems — and what that might mean for the future.

“Maybe we’re still in kind of the recovery from this extinction, maybe there is speciation ongoing, if we let it run for long enough, there would be large mammals again”, says Prof. Fritz.

Join us for a fascinating conversation about evolutionary history and biodiversity change over very long time scales, and what lessons we might be able to draw from the past and apply when looking at biodiversity today.

Related links:

Prof. Dr. Susanne Fritz at iDiv:

Paper on mammalian diversity change:

Paper on past mammalian body size change:

Paper on bird migration:

Paper on future bird diversity change:

Host: Dr. Volker Hahn, Head of Media and Communications at iDiv

While some biodiversity change trends are deeply worrying, such as the decline of common bird species in North America, others offer hope, such as the recovery of rare birds: “I've seen in my lifetime species that were locally extinct come back, and rivers that were dead come back to life,” says Inside Biodiversity guest Henrique Pereira. “And that's because there's been so much positive development from environmental policy in Europe and in other countries in the world.”

In this episode, we explore why biodiversity change isn’t a single story of loss and why it is important to understand the complexity of the issue for science, communication, and policy.

Other topics we cover:

Join us as we discuss these issues with Professor Henrique Pereira, research group leader at iDiv and the Martin Luther University Halle-Wittenberg.

Links:

Prof. Dr. Henrique M. Pereira at iDiv:

Science paper on biodiversity trends and scenarios:

Public talk about rewilding European landscapes:

Host: Dr. Volker Hahn, Head of Media and Communications at iDiv

Is biodiversity loss always bad? What if cutting down an old-growth forest actually increases the number of species? According to biodiversity researcher Jonathan Chase, “You can have huge levels of biodiversity in habitats that are strongly degraded by people.”

In this episode, we explore how biodiversity changes can be counterintuitive, and why measuring it is more complicated than just counting species. If biodiversity isn't inherently good or bad, then what do we—as individuals and as a society—value about nature? We discuss these questions in this episode of Inside Biodiversity with Jonathan Chase, professor at iDiv and the Martin Luther University Halle-Wittenberg.

Other topics discussed include:

Links:

Professor Jonathan Chase at iDiv:

Paper on “detection and attribution” in biodiversity research, discussed in this episode:

TEDx talk by Jonathan Chase, “Biodiversity scientists as honest brokers or advocates?”:

Host: Dr. Volker Hahn, Head of Media and Communications at iDiv

In this episode of Inside Biodiversity, we talk to Andrew Gonzalez about how biodiversity is changing – and how humans are driving this process. Gonzalez discusses shifts in species composition, critiques conclusions drawn from time-series analyses we covered in episode one, and calls for better data to link changes to human impacts. Drawing on climate science, he proposes a “detection and attribution” approach and urges scientists to focus on solutions. A thought-provoking look at the science and communication of biodiversity change.

Links:

Professor Andrew Gonzalez’s profile at McGill University: https://www.thegonzalezlab.org/about-andrew-gonzalez

Paper critiquing analyses of time-series data, which have suggested biodiversity is not declining at local scales:

Paper on “detection and attribution” in biodiversity research, discussed in this episode:

Episode summary:

Andy Gonzalez, a biodiversity scientist at McGill University, explores the complexity of biodiversity change and urges caution against oversimplified narratives of biodiversity decline. He acknowledges that while extinction is real and alarming, biodiversity is not uniformly decreasing — many local communities are experiencing reorganization rather than outright loss, with changing species compositions and shifting abundances.

Gonzalez critiques time-series data analyses we discussed in episode one for their geographic and taxonomic biases and argues that we lack a truly global, representative understanding of biodiversity trends.

Drawing inspiration from climate science, he promotes a “detection and attribution” framework to better link observed biodiversity changes to human drivers.

Gonzalez stresses the need for standardized, long-term data collection and a focus on causal understanding. Gonzalez also highlights the importance of shifting communication from loss to actionable solutions, suggesting that focusing solely on negative trends risks alienating the public. Instead, he calls for a balanced, evidence-based narrative that recognizes both the challenges and potential of biodiversity conservation.

Host: Volker Hahn

In this episode of Inside Biodiversity, we look at one of the most controversial questions in biodiversity research: How ubiquitous is biodiversity loss? Our guest, Maria Dornelas, has challenged overly simplistic narratives of how biodiversity is changing. We discuss the current state of knowledge and how best to communicate it. Whether you are a sceptic or an advocate of biodiversity conservation, this conversation will give you new insights into the fascination and complexity of biodiversity change.

Maria Dornelas is a Professor at the University of St Andrews and the University of Lisbon, specializing in global biodiversity patterns, species diversity, and ecological change. Her research challenges common assumptions about biodiversity loss, using long-term data to reveal complex trends.

Links:

Maria Dornelas’s profile at the University of St Andrews: https://www.st-andrews.ac.uk/biology/people/maadd

Controversial paper discussed in this podcast episode: Assemblage Time Series Reveal Biodiversity Change but Not Systematic Loss https://www.science.org/doi/10.1126/science.1248484

Recent review paper: Looking Back on Biodiversity Change: Lessons for the Road Ahead https://royalsocietypublishing.org/doi/full/10.1098/rstb.2022.0199

Episode summary:

Maria Dornelas, a macroecologist at the University of St. Andrews and the University of Lisbon, challenges the common view that biodiversity is uniformly declining. Her research, based on the BioTIME database, reveals a more complex picture, with biodiversity trends varying by location—some areas remaining stable or even seeing increases in species diversity.

She discusses the "biodiversity conservation paradox," where human activities alter ecosystems, yet biodiversity declines are not universal. While biodiversity loss is real, it is part of a broader story that includes species turnover and recovery. Dornelas advocates shifting the focus from "biodiversity loss" to "biodiversity change."

Addressing criticisms, she acknowledges limitations like short analysis timeframes and regional biases in monitoring but emphasizes that her findings remain valuable. She calls for a more nuanced conservation approach, highlighting successes alongside challenges. Overly simplistic narratives, she warns, risk disengaging the public—echoing mistakes made in climate communication. Instead, she urges balanced messaging and expanded global biodiversity monitoring efforts.

Host: Volker Hahn

Inside Biodiversity is hosted by the German Centre for Integrative Biodiversity Research (iDiv).