What does bioturbation refer to?

Bioturbation refers specifically to the disturbance of sedimentary deposits by living organisms. This process occurs when organisms, such as burrowing animals, worms, and microbes, move through sediment layers, mixing and redistributing the material. This activity can significantly alter the physical and chemical properties of sediments, affecting their composition and structure. Bioturbation plays a crucial role in various ecological processes and can influence nutrient cycling, sediment stability, and habitat complexity.

The other options relate to different concepts in ecology and evolution. For instance, the movement of organisms across ecosystems addresses migration and dispersal but does not capture the specific sediment interaction characteristic of bioturbation. Natural selection impacting genetic variation pertains to evolutionary biology and the mechanisms of evolution, while the evolution of cooperative behaviors is a distinct topic concerning social biology. None of these options accurately define the specific actions and implications of bioturbation as it pertains to sediment disturbance.