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Species go extinct constantly as environments change, as organisms compete for environmental niches, and as genetic mutation leads to the rise of new species from older ones. At long irregular intervals, Earth's biosphere suffers a catastrophic die-off, a mass extinction , [ 9 ] often comprising an accumulation of smaller extinction events over ...
[1]: 229 However, a biozone may vary in age from one location or another. For example, a given taxon may migrate, so its first appearance varies from place to place. In particular, facies-controlled organisms (organisms that lived in a particular sedimentary environment ) are not well suited for biochronology because they move with their ...
Variation is a major part of what LHT studies, because every organism has its own life history strategy. Differences between strategies can be minimal or great. [5] For example, one organism may have a single offspring while another may have hundreds. Some species may live for only a few hours, and some may live for decades.
Land plants evolved from a group of freshwater green algae, perhaps as early as 850 mya, [3] but algae-like plants might have evolved as early as 1 billion years ago. [2] The closest living relatives of land plants are the charophytes, specifically Charales; if modern Charales are similar to the distant ancestors they share with land plants, this means that the land plants evolved from a ...
On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (1st ed.). London: John Murray. ISBN 978-1-4353-9386-8. Darwin, Charles (1872). The Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (6th ed.). London: John Murray.
Adaptation – Process that fits organisms to their environment; Adaptive radiation – A process in which organisms diversify rapidly from an ancestral species; Coevolution – Two or more species influencing each other's evolution; Concerted evolution; Convergent evolution – Independent evolution of similar features
[26] [27] Organisms are merely the outcome of variations that succeed or fail, dependent upon the environmental conditions at the time. Rapid environmental changes typically cause extinctions. [28] Of all species that have existed on Earth, 99.9 percent are now extinct. [29]
At the same time, Sahara is green with rivers, lakes, cattle, crocodiles and monsoons. At 8 ka, Common (Bread) wheat (Triticum aestivum) originates in southwest Asia due to hybridisation of emmer wheat with a goat-grass, Aegilops tauschii. At 6.5 ka, two rice species are domesticated: Asian rice, Oryza sativa, and African rice Oryza glaberrima.