Dr. Rafał Zwolak, a professor in the Department of Biology, Adam Mickiewicz University in Poznań, Poland, discusses his paper, “Animal personalities and seed dispersal: A conceptual review”, as well as his favorite research project and his opinions on the best and worst parts about being an ecologist.

Dr. Rafał Zwolak
Dr. Rafał Zwolak

About the paper

What’s your paper about?

Yellow-necked mouse. These rodents and their interactions with masting trees such as beech and oak are one of the main study subjects in dr. Zwolak’s lab. Photo Credit: Julia & Staszek Pagacz.
Yellow-necked mouse. These rodents and their interactions with masting trees such as beech and oak are one of the main study subjects in dr. Zwolak’s lab. Photo Credit: Julia & Staszek Pagacz.

We outline diverse ways in which behavioural types might affect seed dispersal, and discuss potential ramifications for plant recruitment. Even within species, animals differ in tendencies for particular behaviours, and these tendencies typically occur in predictable associations. For example, highly aggressive individuals usually also have a high level of locomotory activity, a high propensity to take risks when foraging, and are slow to adjust their behaviour to changes in the environment relatively to less aggressive individuals. The phenomenon of behavioural types, also known as “animal personalities”, has been the focus of intense research for the last couple of decades. Scientists found that behavioural types influence important ecological phenomena, such as predator-prey interactions and biological invasions. However, the role of behavioural types in animal-mediated seed dispersal has been largely overlooked. This is surprising, because the number and fate of the disseminated seeds is determined by the behaviour of animal dispersers – and now we know this behaviour is shaped and constrained by personalities.

What are the key messages of your article?

Beech seedling. Photo Credit: Julia & Staszek Pagacz.
Beech seedling. Photo Credit: Julia & Staszek Pagacz.

We argue that examining behavioural differences between individuals allows for more complete understanding of the mechanisms and consequences of seed dispersal by animals. Traditionally, seed dispersal has been examined at the species level. So, researchers would usually ask how a particular tree or shrub species interacts with a particular monkey or bird species. More recently, this has been complemented by a coarser approach of functional groups. An example of this method would be to search for patterns in seed dispersal by large- vs. small-bodied mammals. This is of course valuable and important, but some of the variance in the dynamics and outcomes of seed dispersal can only be explained at the lower level – the level of individual.

About the Author

What project/article are you most proud of?

My favourite research projects are those that I carried out in mountains – maybe because I live in the flattest part of Poland. As a part of my PhD research, I examined the impact of seed predation by deer mice on seedling establishment in burned and unburned forest in Montana. It turns out that forest fires create great conditions for seedling germination, but mice, which are very abundant in burned forests and are voracious seed predators, completely obliterate this effect. I used a typical design with tree seeds sown in rodent exclosures (small wire cages) and controls (cages with holes). In the unburned forest, few seeds germinated into seedlings, regardless of treatment. In the burned forest, there were plenty of seedlings in mouse exclosures, but none, not even a single one, in control cages. I have never seen more clearcut results.

Bieszczady Mountains. Photo Credit: Julia & Staszek Pagacz. Bieszczady Mountains. Photo Credit: Julia & Staszek Pagacz.
Bieszczady Mountains. Photo Credit: Julia & Staszek Pagacz.

More recently, in Polish Bieszczady mountains, we had an opportunity to observe the impact of mast seeding on small mammals. After masting, forest small mammals capitalized on the extra food, increased in abundance and spilled over above the treeline, into mountain meadows. I expected negative, competition-driven effects of this spillover on the abundance of meadow rodents. Instead, the influx of forest rodents triggered an increase in the meadow ones, probably because the sudden bounty of prey temporarily overwhelmed predator ability to control rodent populations.

Beech forest in Bieszczady Mountains. Photo Credit: Julia & Staszek Pagacz.
Beech forest in Bieszczady Mountains. Photo Credit: Julia & Staszek Pagacz.

What is the best thing about being an ecologist?

I simply enjoy learning things about stuff that I find interesting. So, I’m lucky that my job boils down to acquiring information about the living world. Creating new knowledge in primary research is important and rewording, but I also genuinely like reading publications and learning about other people’s research. This might explain why quite a few of my articles are reviews and meta-analyses.

What is the worst thing about being an ecologist?

Well, researchers are expected to strive for excellence on so many fronts. You have to conduct high-quality research (naturally), but also be an engaging teacher, inspiring mentor, find ingenious ways to disseminate your results, and so on. All of that while maintaining healthy work-life balance, of course. And countless blog entries and articles will tell you that you really need to put more effort in this or that. Otherwise you are hurting your career or not fulfilling your moral obligations. This can be overwhelming and it is helps to remember that sometimes you don’t need to outrun the bear, just the slowest person.

What do you do in your spare time?

I spend most of my free time doing all kinds of pull-ups, cleans, and deadlifts. I’m quite compulsive about it.

Read the paper in full here.