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Charismatic species are often used as flagship species in conservation programs, as they are supposed to affect people's feelings more. [2] However, being charismatic does not protect species against extinction; all of the 10 most charismatic species are currently endangered, and only the giant panda shows a demographic growth from an extremely small population.
Carcinisation (American English: carcinization) is a form of convergent evolution in which non-crab crustaceans evolve a crab-like body plan. The term was introduced into evolutionary biology by L. A. Borradaile, who described it as "the many attempts of Nature to evolve a crab". [2]
Mosaic evolution – Evolution of characters at various rates both within and between species; Parallel evolution – Similar evolution in distinct species; Quantum evolution – Evolution where transitional forms are particularly unstable and do not last long; Recurrent evolution – The repeated evolution of a particular character
The word evolved in a modern sense was first used in 1826 in an anonymous paper published in Robert Jameson's journal and evolution was a relative late-comer which can be seen in Herbert Spencer's Social Statics of 1851, [a] and at least one earlier example, but was not in general use until about 1865–70.
The second is the notion of branching evolution, implying the common descent of all species of living things on earth from a single unique origin." [11] Additionally, "Darwin further noted that evolution must be gradual, with no major breaks or discontinuities. Finally, he reasoned that the mechanism of evolution was natural selection." [11]
If a species integral to an ecosystem has been lost due to extinction, a related species will be placed to fulfil the same role and re-establish the ecosystem function. These typically range from a related sub-species to another species within the same genus. [1] An example of such is the ecological services herbivores provide.
There are over 800 described species, and according to estimates, there could be well over 1,600 species in the region. Their evolution is cited as an example of both natural and sexual selection. [40] [41] A 2008 study suggests that sympatric speciation has occurred in Tennessee cave salamanders. [42]
The tree of life or universal tree of life is a metaphor, conceptual model, and research tool used to explore the evolution of life and describe the relationships between organisms, both living and extinct, as described in a famous passage in Charles Darwin's On the Origin of Species (1859). [1]