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This contact allows for the potential for the exchange of genes, dependent on how reproductively isolated the two populations have become. There are several primary outcomes of secondary contact: extinction of one species, fusion of the two populations back into one, reinforcement , the formation of a hybrid zone , and the formation of a new ...
Direct reciprocity was proposed by Robert Trivers as a mechanism for the evolution of cooperation. [1] If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to "cooperate" or "defect", then a strategy of mutual cooperation may be favoured even if it pays each player, in the short term, to defect when the other cooperates.
In these examples, the source of selection on a trait coevolves with the trait itself, therefore causation is reciprocal and developmental processes potentially become relevant to evolutionary accounts. For instance, a peacock’s tail evolves through mating preferences in peahens, and those preferences coevolve with the male trait.
By stotting (also called pronking), a springbok (Antidorcas marsupialis) signals honestly to predators that it is young, fit, and not worth chasing.. Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals, both within species and across species.
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.
Invertebrates have several other types of specific junctions, for example septate junctions (a type of occluding junction) [4] or the C. elegans apical junction. In multicellular plants , the structural functions of cell junctions are instead provided for by cell walls .
The pygmy mammoth is an example of insular dwarfism, a case of Foster's rule, its unusually small body size an adaptation to the limited resources of its island home.. A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms.
Objections to evolution have been raised since evolutionary ideas came to prominence in the 19th century. When Charles Darwin published his 1859 book On the Origin of Species, his theory of evolution (the idea that species arose through descent with modification from a single common ancestor in a process driven by natural selection) initially met opposition from scientists with different ...