Tectonic plate movements influence biodiversity

A study reveals that the movements of Earth's tectonic plates indirectly trigger biodiversity explosions in cycles of 36 million years by forcing sea levels to rise and fall.

Structure of Earth's lithosphere

The lithosphere is divided into several plates that float and move slowly over the asthenosphere, a layer of partially molten rock located below. There are a dozen major plates, such as the Eurasian plate, the African plate, or the North American plate, as well as minor plates.

Types of plate boundaries

All are composed of the Earth's crust and the upper part of the mantle. These plates being mobile, it is natural that they sometimes meet. These meeting points are called "plate boundaries." There are three main types: Convergent boundaries, where the plates move toward each other.

Effects of convergent boundaries

When two continental plates collide, they form mountain ranges. If an oceanic plate collides with a continental plate, it subducts beneath the continental plate in a process called subduction, forming oceanic trenches and volcanic chains.

Divergent and transform boundaries

Divergent boundaries, where the plates move away from each other. This generally occurs in the oceans where magma rises through cracks, forming new oceanic crust and oceanic ridges. Transform boundaries, where the plates slide horizontally relative to each other. This creates transform faults such as the famous San Andreas Fault in California.

Geological events and marine habitats

Researchers from the University of Sydney have discovered that these geological events provide new habitats for marine life to flourish. As water levels rise and fall, different habitats on continental shelves and in shallow seas expand and contract.

Impact on marine biodiversity

When sea levels rise and coasts are flooded, this can create pockets of shallow seas that may eventually give rise to new species particularly adapted to these newly formed habitats. The study, published in the Proceedings of the National Academy of Sciences, provides additional evidence that global sea level changes driven by Earth's geological processes influence the biodiversity of marine life.

Long-term geological cycles

Researchers believe that these geological cycles of sea level changes have had a significant impact on marine species diversity for at least 250 million years. Their analysis also revealed that tectonic changes leading to shallower sea levels within and around continents occurred every 36 million years.

Correlation with biodiversity

These cycles were correlated with periods of great biodiversity in the fossil records recorded approximately six to eight million years later. According to the cycle, Earth is currently at a low point in sea level, which would therefore correspond to low marine biodiversity, if we only considered changes induced by tectonics.

Human influence on sea levels

However, the movement of tectonic plates is not the only thing that can modify sea levels and, therefore, ocean biodiversity. Human-induced climate change is indeed warming ocean temperatures, melting glaciers, thus contributing to a global rise in sea levels.

Influence on terrestrial ecosystems

Furthermore, tectonic cycles do not only influence marine biodiversity. They also have a marked influence on terrestrial ecosystems by shaping continents and creating new habitats. For example, the formation of mountain ranges and high plateaus, resulting from collisions between tectonic plates, modifies local precipitation and temperatures, thereby promoting the development of diverse ecological zones.

Creation of unique habitats

These regions can host endemic species that specialize in unique environments, thus enriching terrestrial biodiversity.