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Documented examples are found in a wide range of organisms: both vertebrates and invertebrates, fungi, and plants. The secondary contact of originally separated incipient species (the initial stage of speciation) is increasing due to human activities such as the introduction of invasive species or the modification of natural habitats . [ 6 ]
Shifting balance theory aims to explain how this may be possible. The shifting balance theory is a theory of evolution proposed in 1932 by Sewall Wright , suggesting that adaptive evolution may proceed most quickly when a population divides into subpopulations with restricted gene flow .
The search space is only part of an evolutionary landscape. The final component is the "y-axis", which is usually fitness. Each value along the search space can result in a high or low fitness for the entity. [1] If small movements through search space cause changes in fitness that are relatively small, then the landscape is considered smooth.
At the most fundamental level, Charles Darwin's theory of evolution states that organisms evolve and adapt to their environment by an iterative process. This process can be conceived as an evolutionary algorithm that searches the space of possible forms (the fitness landscape) for the ones that are best adapted. The process has three components:
Aristotle considered whether different forms could have appeared, only the useful ones surviving.. Several philosophers of the classical era, including Empedocles [1] and his intellectual successor, the Roman poet Lucretius, [2] expressed the idea that nature produces a huge variety of creatures, randomly, and that only those creatures that manage to provide for themselves and reproduce ...
Evolution can be extremely rapid, as shown in the creation of domesticated animals and plants in a very short geological space of time, spanning only a few tens of thousands of years. Maize ( Zea mays ), for instance, was created in Mexico in only a few thousand years, starting about 7,000 to 12,000 years ago. [ 88 ]
The semi-antagonistic relationship is best illustrated using the corridor model, whereby stabilizing selection forms barriers in phenotype space that only allow the system to move towards the optimum along a single path. This allows directional selection to act and inch the system closer to optimum through this evolutionary corridor.
Neutral networks are a subset of the sequences in sequence space that have equivalent function, and so form a wide, flat plateau in a fitness landscape. Neutral evolution can therefore be visualised as a population diffusing from one set of sequence nodes, through the neutral network, to another cluster of sequence nodes.