Species Extinction
Species extinction refers to the permanent disappearance of a species from the Earth. This process occurs through two primary pathways: deterministic and stochastic processes.
Deterministic and Stochastic Processes
- Deterministic processes have specific causes and predictable effects. These include phenomena such as glaciations or human-induced changes like deforestation, which directly lead to habitat loss or species decline. On the other hand, stochastic processes involve chance and randomness. These include unpredictable changes such as sudden shifts in weather patterns, food shortages, outbreaks of disease, or unexpected increases in predator or parasite populations. These processes may act alone or alongside deterministic effects to cause extinction.
Vulnerability to Extinction
- Certain traits increase a species’ susceptibility to extinction. These include low population numbers, poor ability to disperse, ecological specialization, unstable population dynamics, and a position at higher trophic levels. Carnivores, for instance, are generally fewer in number and therefore more vulnerable. Additionally, low survival rates, low reproductive capacity, and dependence on specific diets or body sizes can also increase extinction risk.
Natural Extinctions
- Throughout Earth’s history, species have gone extinct due to natural causes such as continental drift, climate change, tectonic shifts, and volcanic activity. For example, the Late Ordovician glaciation event around 439 million years ago and the mass extinction during the Late Cretaceous period, which is thought to be caused by an asteroid impact, are notable instances of natural extinctions. In many cases, plant extinction has occurred gradually due to evolutionary processes or environmental changes.
Artificial Extinction
- Artificial extinction is largely the result of human activities and occurs at a rate much higher than natural extinction. Species face extinction due to direct human actions like hunting, poaching, and capturing. Indirectly, human activities such as habitat destruction, pollution, and the introduction of invasive species further accelerate the process. While natural extinction is a slow and gradual event, artificial extinction is rapid and often irreversible.