At the origin of biodiversity

Ecosystems, and all their elements, are closely related to the entire biosphere and the mechanisms that make up the Earth system. A recent study has highlighted the intricate relationship between geological changes, biodiversity and the formation of ecosystems. The scientists Boulila and Müller, from the Sorbonne University of Paris and the University of Sydney respectively, have identified a geological cycle in tectonic plate movements that they think may have influenced the development of marine biodiversity. The cycle has a duration of about 36 million years and would have started 250 million years ago.

Researchers point out that biodiversity levels of marine animal fossils show an almost cyclical trend over time scales spanning tens of millions of years. These trends have been correlated with similar trends observed in sea levels and tectonic plate movements, suggesting that marine biodiversity, over the long term, has been influenced by cycles of rising and falling waters, in turn driven by geological mechanisms. Variability in biodiversity would thus be linked to periodic flooding or drying up of land, causing a contraction (or vice versa a dilation) of ecological niches in coastal areas.

The research focused on the Queensland area in the central region of Australia. The researchers cite in particular the Winton Formation, a deposit of sedimentary rocks formed in the basin left by the Eromanga Inland Sea, which over the geological eras covered the land at least four times. Sediments were carried by large, winding rivers, swampy forests, inlets and estuaries, which have now disappeared, until the entire area previously occupied by the sea was covered 95 million years ago. Because of its nature, the Winton Formation is one of the most important fossil sources in Australia, fossils used to assess precisely the variability of the biodiversity of marine animal species that once inhabited the area.

The earth's crust, together with the uppermost part of the mantle below, forms the lithosphere. This is divided into 20 major tectonic plates and many micro plates. The tectonic plates are never stationary, but move due to the slow and regular convective movements of the underlying fluid mantle. According to the theory of plate tectonics, the heat from the Earth's centre provides the energy to heat the magma, which then rises upwards: in the upper layers it cools down again and then falls back down into the depths, generating the convective movements.

Geological cycles would thus be a kind of pendulum of biodiversity. The movements of tectonic plates have led to alterations of the seabed and the transfer of water and biological material to the inner layers of the earth's crust. The resulting fluctuation of sea levels saw "periods when the seas were wide and shallow, perfect for the growth of biodiversity," explains the article's co-author Dietmar Müller. The change in habitats means new opportunities for organisms to evolve and reproduce, giving rise to new speciation events.

According to some, however, the software used in the study would not take into account several variables, including the Milankovic cycles, which are the set of cyclical variations on the Earth's climate due to the planet's rotation in orbit and its axial tilt, which are fundamental for glaciation phenomena in particular. For the authors of the study, however, these cycles would be less impactful than the identified geological cycles. Moreover, it is questioned whether animal species could actually have adapted to habitat changes so abruptly, considering the very slow mechanisms that drive the emergence of new organisms. Buolila and Müller do, however, appeal to the numerous data analysed by the fossil record, which show clear signs of biodiversity explosions in certain geological eras.

The study of geological mechanisms must be deepened in order to perfect computer models and understand how they can influence ecosystems and what the origins of biodiversity are, reminding us of how each phenomenon on our planet cannot be considered in isolation, but must be seen within a complex network. Biogeochemical fluxes, i.e. the closed path followed by a particular chemical element within the ecosphere, make it clear how atmosphere, hydrosphere, lithosphere and biosphere are closely and inextricably linked.

It is evident how much the characteristics and health of a given habitat influence the species that inhabit it. By habitat is meant, in fact, the set of physical and chemical (but also geological, climatic and geographical) environmental conditions that are optimal for the development of a specific species. Habitats are thus a fundamental component of biodiversity. The UN Convention on Biological Diversity defines, in fact, biodiversity as the variety and variability of living organisms and their ecological systems, highlighting, among others, also the ecosystem level: this describes the number and abundance of habitats and living communities that, through a complex network of relationships, form the functional unity of the ecosystem. The safeguarding of biodiversity must, therefore, necessarily pass through actions of regeneration of natural and urban habitats, such as those promoted by 3Bee with the Oases of Biodiversity.

Among the main causes of biodiversity loss, a key role is played by the destruction and fragmentation of natural habitats. While some changes in the habitats of certain species can be traced back to natural phenomena, such as the tectonic cycles illustrated in the article, to date the loss of habitats is almost entirely due to anthropogenic action, with the expansion of the human population and its activity, supported by massive land consumption. Pollution and habitat destruction are assuming massive proportions: according to the EU, three quarters of marshes and bogs and almost half of lakes, rivers and coastlines are in danger of disappearing, bringing with them a disastrous loss of animal and plant species.

3Bee places the regeneration of habitats and biodiversity at the centre of its action. Through the use of advanced technologies, such as Flora, developed in collaboration with ESA, 3Bee is able to monitor habitats and estimate their potential biodiversity, boundary conditions and their suitability to host and nurture pollinators. In the Oases of Biodiversity, innovative technologies are put at the service of the regeneration of natural and urban ecosystems. One of 3Bee's goals is to create Europe's largest ecological corridor for pollinator insects: green areas to connect habitat zones fragmented by human action. Join 3Bee to help protect biodiversity through technology.



Article edited by Sabina Sacchetti