November 11 () –
For the first time it has been shown, in biological systems with a single species, that unpredictable chaos-like dynamics can emerge under completely constant external conditions.
Such dynamics, for example, fluctuations in population density, they occur even without interactions with the environment or with other species.
This may explain why such an enormous diversity of species has evolved on our planet. If, contrary to previous assumptions, different species and evolutionary lineages are subject to irregular chaotic dynamics in themselves, they never encounter the same number of individuals at the same time. Since direct competition between species becomes rare, they can coexist and evolve for much longer periods of time.
The study, carried out by scientists from the universities of Cologne and Osnabruck, has appeared in Proceedings of the National Academy of Sciences (PNAS).
Biodiversity refers to the variety of life at all levels, from genes to entire ecosystems. It encompasses evolutionary, ecological and cultural processes. It is not just about species that we consider rare, threatened or endangered, but about all living things, from humans to organisms we know little about, such as microorganisms, fungi and small invertebrates.
Biodiversity is an essential part of our lives. In addition to maintaining the stability of our own habitat, it also contributes to the satisfaction of many basic human needs, including as food, and serves as a provider of energy or as a basis for medicines. Furthermore, biodiversity is important for pollination and seed dispersal and for the control of agricultural pests.
High biodiversity is a prerequisite for climate regulation. Nutrient cycling and the purification of drinking water and wastewater also require a high diversity of organisms. Humanity is currently destroying biodiversity at an alarming rate. A quarter of all species are considered threatened.
This study, which involved the research group of Professor Dr. Hartmut Arndt, at the Institute of Zoology at the University of Cologne, investigated the mechanisms that have led to the diversity of species on our planet and what we need to consider to ensure that these mechanisms continue to be effective. Arndt and his team have been studying the dynamic processes of species coexistence. as the basis for evolutionary processes in model organisms for many years.
Using laboratory experiments and modeling data, scientists have shown for the first time that unequal dynamics in the number of individuals in a population can significantly affect species coexistence even at the level of a single cell type without external drives. The importance of fluctuations in population densities and deterministic chaos (seemingly chaotic behavior even though the underlying conditions seem predictable) it has been discussed for several decades as an important factor in species diversity in natural biological systems.
The two doctoral researchers Johannes Werner and Tobias Pietsch from Arndt’s team have now shown that, contrary to expectations, the evolutions of single-species systems in a continuous flow of nutrient medium exhibit dynamics that are not simple, even showing characteristics of deterministic chaos. .
That is, unpredictable fluctuations in the number of individuals occur even under fairly constant conditions and without interactions between different species or fluctuating environmental conditions. These data were supplemented by a modeling study conducted with the theorist Frank Hilker at the University of Osnabrück. “The fairly simple and general model that we developed for the analysis of the cell division cycle exhibits a remarkable range of dynamic behavior“, He says it’s a statement Johannes Werner, first author of the study.
The observed phenomenon has fundamental consequences for understanding evolutionary processes because the potential coexistence of competing species or cell lineages in changing abundance it is an important foundation for high biodiversity on Earth.
“Allowing for these fluctuations is essential to protect biodiversity and its functions. Nature reserves, for example, must be large enough so that natural ups and downs in the number of individuals of a species do not lead to complete extinction and ensure survival. of the species, even in extreme weather conditions“, explained Hartmut Arndt.
