Botany 2025, one of the year’s most anticipated academic botany events, is just around the corner. Botany One has interviewed Dr Marcelo A. Aizen, one of the conference’s keynote speakers, who is sponsored by the Annals of Botany journal, to learn more about his fantastic work in pollination ecology.
Aizen completed his bachelor’s degree at the University of Buenos Aires and then moved to the University of Massachusetts to complete his PhD. Now, he is a Senior Researcher at the National Research Council of Argentina (CONICET) and a Full Professor in the Department of Ecology at the National University of Comahue, leading the Pollination Ecology group. His research has been focused on a wide variety of topics related to plant reproduction: from the study of pollen tube-pistil interactions to global assessment of pollinator declines and the so-called pollination crisis. You can learn more about his research on his website.
What motivated you to pursue your current area of research?
After graduating, I started working in the SPIDER (Special Programme for the Improvement and Development of Ecological Research) programme, which aimed to promote research in environmental sciences by connecting Argentine ecologists with renowned Argentine scientists working abroad, as well as with foreign researchers interested in contributing to our country’s scientific development. During this project, I travelled to promote the project in a international symposium on plant-animal interactions, held in Santiago de Chile. During the event, I met Peter Feinsinger, who at the time was a professor at the University of Florida and a leading figure in plant-hummingbird interactions from a community ecology perspective. His talk at that symposium fascinated me and sparked my passion for pollination ecology. After hearing his presentation, I knew for certain that I wanted to work on “that”. So certain I was, that I changed the topic of my PhD that I started a couple of months before meeting Peter.
What is your favourite part of your work related to plants?
I find it truly fascinating to understand how the evolution of flowers in early angiosperms granted this plant group unparalleled evolutionary potential and how this diversification influenced the evolution of various animal groups that have specialised in relying on floral resources. From an applied perspective, the relevance of these interactions in biodiversity conservation and food production has also guided my work. I believe that what is truly important, in my case, is not having confined my research to strictly basic or applied fields but instead having established strong bridges between the two.
Are there any specific plants or species that have intrigued or inspired your research?
Interestingly, my most surprising discovery is not directly related to pollination but to seed dispersal. In 1997, along with Guillermo Amico, who was then an undergraduate student, we began working on a project investigating why the mistletoe Tristerix corymbosus or “quintral”, found in Patagonian forests, blooms in winter. One of our hypotheses about the advantage of flowering during this time of the year was that it would ensure seed dispersal, as fruits would ripen when dispersers are most active. According to our hypothesis, flowers opening in mid-winter not only produced more fruits, but nearly all of them, maturing in mid-summer, were removed by dispersers. The thing was that we had no idea who was dispersing them! According to the literature, mistletoes are universally dispersed by birds, but we never observed any bird consuming these mistletoe fruits in Patagonian forests.
After a detective-like investigation, we finally identified the disperser. The answer was surprising—the disperser was not a bird but a nocturnal mammal! Not just any mammal, but a marsupial called Dromiciops gliroides, or the monito del monte. This tree-dwelling marsupial from Patagonian forests is the sole representative of an ancient marsupial lineage dating back to Gondwana. It is more closely related to Australian kangaroos than to American opossums. We even speculated that the ancestors of this tiny creature might have been dispersing mistletoe seeds long before birds even appeared.
Could you share an experience or anecdote from your work that has marked your career and reaffirmed your fascination with plants?
The discovery of the first mistletoe species worldwide dispersed by a mammal—particularly a marsupial—had profound evolutionary implications and was published in Nature. However, the most gratifying part was seeing this story take on a life of its own and become part of the local knowledge in Bariloche, where I live. An anecdote related to this is that my youngest son, Marco, was in second grade at the time when his teacher told the class about the story of the quintral and the monito del monte as an example of the intricate interactions that weave the fabric of life in our forests. When the teacher finished, my son proudly raised his hand and said, “My dad discovered that.” I couldn’t ask for a greater reward!
What advice would you give young scientists considering a career in pollination ecology?
I have three pieces of advice. First, let curiosity be your main motivation—regardless of whether your research topic is trendy or its future impact is uncertain. When we began working on what is now called “pollination services,” very few researchers considered field edges or remnants of natural habitat as sources of pollinators. Our interest in this topic stemmed from curiosity and was a logical extension of our studies on habitat fragmentation and plant-pollinator interactions.
Second, I strongly believe that advancing knowledge in plant reproductive ecology requires us to open the “black box” of pollination—something pollination ecologists rarely do. For instance, what are the post-pollination consequences (e.g., pollen germination, pollen tube growth) of receiving too much or too little pollen, pollen from different sources, or pollen with varying genetic diversity? Recent trends in pollination research, such as studying plant-pollinator networks or ecosystem services, have led us to overlook the fact that pollination is more than just animals visiting flowers and plants producing seeds. We need a less phenomenological and more mechanistic approach to plant-pollinator studies that delves into the details of pollination.
Third, challenge established paradigms and question the assumptions behind widely accepted hypotheses. You may be surprised to find that many are built on shaky foundations. This was the case with the simplistic version of the so-called global pollination crisis, which claims that bee declines due to anthropogenic impacts will lead to food shortages. The harsh reality is that humans will likely disappear before all bees do, and the contribution of bees to global agricultural production is overestimated. This does not mean that pollinators are unimportant in agriculture—particularly for crops that produce fruits and seeds with high nutritional value. However, our work has challenged the simplistic idea that pollinator declines will inevitably cause severe food shortages. This challenge was based on quantifying pollinators’ role in food production and the lack of evidence linking pollinator decline to reduced agricultural yields.
Carlos A. Ordóñez-Parra
Carlos (he/him) is a Colombian seed ecologist currently doing his PhD at Universidade Federal de Minas Gerais (Belo Horizonte, Brazil) and working as a Science Editor at Botany One and a Communications Officer at the International Society for Seed Science. You can follow him on BlueSky at @caordonezparra.
