Diferenzas entre revisións de «Radiación adaptativa»

== Identificación ==
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# Un antepasado común das especies compoñentes: especificamente un antepasado ''recente''. Nótese que isto non é o mesmo que unha [[monofilia]], na cal están incluídos ''todos'' os descendentes dun antepasado común.
# A common ancestry of component species: specifically a ''recent'' ancestry. Note that this is not the same as a [[monophyly]] in which ''all'' descendants of a common ancestor are included.
# Unha correlación fenotipo-ambiente: unha asociación ''significativa'' entre ambientes e os trazos morfolóxicos e fisiolóxicos usados para explotar eses ambientes.
# A phenotype-environment correlation: a ''significant'' association between environments and the morphological and physiological traits used to exploit those environments.
# Utilidade do trazo: as vantaxes de [[fitness (bioloxía)|fitness]] dos valores do trazo nos seus correspondentes ambientes.
# Trait utility: the performance or fitness advantages of trait values in their corresponding environments.
# Especiación rápida: presenza dunha ou máis ''explosións'' na emerxencia de novas especies no momento en que a diverxencia ecolóxica e fenotípica está comezando.
# Rapid speciation: presence of one or more ''bursts'' in the emergence of new species around the time that ecological and phenotypic divergence is underway.
== Causas ==
=== Innovación ===
The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible. A classic example is the evolution of a fourth cusp in the mammalian tooth. This trait permits a vast increase in the range of foodstuffs which can be fed on. Evolution of this character has thus increased the number of [[ecological niche]]s available to mammals. The trait arose a number of times in different groups during the [[Cenozoic]], and in each instance was immediately followed by an adaptive radiation.<ref name=Jernvall1996>{{Cite journal | first1 = J. | last1 = Jernvall | first2 = J. P. | last2 = Hunter | first3 = M. | last3 = Fortelius
| title = Molar Tooth Diversity, Disparity, and Ecology in Cenozoic Ungulate Radiations
[[Anolis]] lizards have been radiating widely in many different environments, including Central and South America, as well as the West Indies and experience great diversity of species just as the finches, cichlid fish, and silverswords. Studies have been done to determine whether radiations occur similarly for these lizards on the mainland as they do on the [[Caribbean islands]] or if differences can be observed in how they speciated. It has been observed that in fact, the radiations are very different, and ecological and morphological characteristics that these lizards developed as part of their speciation on the islands and on the mainland are unique.<ref>Irschick, Duncan J., et al. "A comparison of evolutionary radiations in mainland and Caribbean Anolis lizards." Ecology 78.7 (1997): 2191-2203.</ref> They have clearly evolved differently to the environments they inhabit. The environmental pressures on the Anolis lizards are not the same on the mainland as they are on the islands. There are significantly more [[predation|predators]] preying on the Anolis lizards on the mainland. This is but one environmental difference. Other factors play a role in what sort of adaptive radiation will develop. Among the Caribbean islands, a larger perch diameter correlates with longer forelimbs, larger body mass, longer tails, and longer hind limbs. However, on the mainland, a larger perch diameter correlates with shorter tails. This shows that these lizards adapted differently to their environment depending on whether they were located on the mainland or the islands. These differing characteristics reconfirm that most of the adaptive radiation between the mainland and the islands occurred independently. On the islands specifically, species have adapted to certain "microhabitats" in which they require different morphological traits to survive. Irschick (1997) divides these microhabitats into six groups: "trunk–ground, trunk–crown, grass–bush, crown–giant, twig, and trunk." Different groups of lizards would acquire traits for one of these particular areas that made them more specialized for survival in this microhabitat and not so much in others. Adaptive radiation allows species to acquire the traits they need to survive in these microhabitats and reduce competition to allow the survival of a greater number of organisms as seen in many of the examples before.
== Notas ==