Reference: “The effect of dilution on eco-evolutionary dynamics of experimental microbial communities” by Thomas Scheuerl and Veijo Kaitala, 7 September 2021, Ecology and Evolution.The interaction between a consumer (such as, a predator or a parasitoid) and a resource (such as, a prey or a host) forms an integral motif in ecological food webs, and has been modeled since the early 20 th century starting from the seminal work of Lotka and Volterra. How exactly the fluctuations can be explained will be the subject of future research. The point in time at which the experiment was started seemed to play a role, i.e., in which position the predator and prey curves were located. The researchers realized that these were oscillations that occurred when the system was pushed out of equilibrium. Only after inserting an error rate, such a fluctuating dynamic could be simulated. In the observations these were seen and predator-prey cycles were mentioned as a possible explanation, but these were not visible in the theoretical model. Fluctuations in the signalįurthermore, Scheuerl and Kaitala observed that the equilibrium state in the population dynamics of the original experiment did not appear as a constant signal, but fluctuated up and down, which continued in the next generations.

The result: co-evolution had to take place under almost all applied conditions. The theoretical model created in this way made it possible to test how stable the process of co-evolution had to be, allowing a wide range of other assumptions. This is the only way the observed population dynamics and the specific equilibrium state,” says Thomas Scheuerl. “We conclude that predators also had to evolve, i.e., co-evolve, depending on prey. The observed dynamic was reproduced mathematically only when co-evolution of predators and prey was included as a factor. A purely ecological model could not reproduce these observations, when calibrated with parameters taken from the observations. However, both the number of predators and that of prey settled into an equilibrium in the experiment. They found that in a purely ecological process, predator densities should be much lower and even extinction of ciliates should follow. This experiment was the basis of a theoretical study by Thomas Scheuerl of the Research Department for Limnology at the University of Innsbruck in Mondsee and Veijo Kaitala of the University of Helsinki.

In fact, the bacteria had undergone an evolutionary change and had formed an efficient defense trait, presumably by clumping their cells together, making them too large prey for the ciliates. There seemed to be an additional factor that influenced the dynamics.

After a certain point, the number of bacteria did not decrease. They studied microscopic ciliates as predators and bacteria as prey. Defense through evolutionįinnish scientists discovered in 2018 that such theoretical predictions cannot be applied literally to nature. However, predator-prey relationships are also an important cause of evolutionary adaptation. This model only represents ecological dynamics. Thus, when prey is depleted by the predator, an overall population collapse occurs. Increased predation pressure reduces prey densities, which causes predator densities to decrease until prey recovers. Predators find abundant food and also become more abundant. SonntagĬlassical predator-prey models assume that prey organisms evolve unaffected until a predator arrives and decimates the prey.

Predator prey