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Extinctions are a normal part of the evolutionary process, and the background extinction rate is a measurement of "how often" they naturally occur. Normal extinction rates are often used as a comparison to present day extinction rates, to illustrate the higher frequency of extinction today than in all periods of non-extinction events before it. [1]
The dominant account of extinction involves associative models. However, there is debate over whether extinction involves simply "unlearning" the unconditional stimulus (US) – Conditional stimulus (CS) association (e.g., the Rescorla–Wagner account) or, alternatively, a "new learning" of an inhibitory association that masks the original excitatory association (e.g., Konorski, Pearce and ...
In ecology, extinction is sometimes used informally to refer to local extinction, in which a species ceases to exist in the chosen area of study, despite still existing elsewhere. Local extinctions may be made good by the reintroduction of individuals of that species taken from other locations; wolf reintroduction is an example
A different culprit, however, does explain several smaller extinction episodes and at least two mass extinctions, including the largest on record. Apocalyptic volcanoes that caused global warming
Red list categories of the IUCN Demonstrator against biodiversity loss, at Extinction Rebellion (2018).. The current rate of global biodiversity loss is estimated to be 100 to 1000 times higher than the (naturally occurring) background extinction rate, faster than at any other time in human history, [25] [26] and is expected to grow in the upcoming years.
An ecological cascade effect is a series of secondary extinctions that are triggered by the primary extinction of a key species in an ecosystem.Secondary extinctions are likely to occur when the threatened species are: dependent on a few specific food sources, mutualistic (dependent on the key species in some way), or forced to coexist with an invasive species that is introduced to the ecosystem.
An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth.Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms.
Already threatened by the advancement in special effects that create computer-generate crowds, the background acting community is bracing for possible extinction in the wake of COVID-19.