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More than 99 percent of all species, amounting to over five billion species, [7] that ever lived on Earth are estimated to be extinct. [8] [9] Estimates on the number of Earth's current species range from 10 million to 14 million, [10] of which about 1.2 million have been documented and over 86 percent have not yet been described. [11]
Species distribution, or species dispersion, [1] is the manner in which a biological taxon is spatially arranged. [2] The geographic limits of a particular taxon's distribution is its range , often represented as shaded areas on a map.
Darwin argued that species evolved through natural selection from variations within population which he termed as 'varieties'. [ 32 ] Later on, through a series of experiments, Turresson studied the effect of the environment on heritable plant variation and came up with the term 'ecotype' to denote differences between groups occupying distinct ...
Data from about 76,000 butterfly surveys conducted by various groups documenting millions of the insects representing 554 species showed that their numbers dropped by 22% from 2000 to 2
Meanwhile, only 3% of species showed population increases. One of the most striking examples is the monarch butterfly. In December 2024, ...
In a population, carrying capacity is known as the maximum population size of the species that the environment can sustain, which is determined by resources available. In many classic population models, r is represented as the intrinsic growth rate, where K is the carrying capacity, and N0 is the initial population size. [5]
Insects make up the vast majority of animal species. [14]Chapman, 2005 and 2009 [9] has attempted to compile perhaps the most comprehensive recent statistics on numbers of extant species, drawing on a range of published and unpublished sources, and has come up with a figure of approximately 1.9 million estimated described taxa, as against possibly a total of between 11 and 12 million ...
The species concept is further weakened by the existence of microspecies, groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates. [96] For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case ...