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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] Background extinction rates have not remained constant, although changes are measured over geological time, covering millions of years. [2] [3] [4]
Operant extinction differs from forgetting in that the latter refers to a decrease in the strength of a behavior over time when it has not been emitted. [6] For example, a child who climbs under his desk, a response which has been reinforced by attention, is subsequently ignored until the attention-seeking behavior no longer
Permian–Triassic extinction event 252 Ma Large igneous province (LIP) eruptions [ 23 ] from the Siberian Traps , [ 24 ] an impact event (the Wilkes Land Crater ), [ 25 ] an Anoxic event , [ 26 ] an Ice age , [ 27 ] or other possible causes
More significantly, the current rate of global species extinctions is estimated as 100 to 1,000 times "background" rates (the average extinction rates in the evolutionary time scale of planet Earth), [71] [72] faster than at any other time in human history, [73] [74] while future rates are likely 10,000 times higher. [72]
For example, in an article published in 2004, Otso Ovaskainen and Ilkka Hanski explained with an empirical example that when factors such as Allee effect or Rescue effect were included in modeling the extinction threshold, there were unexpected extinctions in a high number of species. A more complex model came up with different results, and in ...
"Behavioral sink" is a term invented by ethologist John B. Calhoun to describe a collapse in behavior that can result from overpopulation.The term and concept derive from a series of over-population experiments Calhoun conducted on Norway rats between 1958 and 1962. [1]
In a landmark paper published in 1982, Jack Sepkoski and David M. Raup identified five particular geological intervals with excessive diversity loss. [2] They were originally identified as outliers on a general trend of decreasing extinction rates during the Phanerozoic, [3] but as more stringent statistical tests have been applied to the accumulating data, it has been established that in the ...
The quasi-extinction threshold, or sometimes called the quasi-extinction risk is the population size below which a species is considered to be at extreme risk of quasi-extinction. [5] This threshold varies by species and is influenced by several factors, including reproductive rates, habitat requirements, and genetic diversity.