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Introgression is an important source of genetic variation in natural populations and may contribute to adaptation and even adaptive radiation. [7] It can occur across hybrid zones due to chance, selection or hybrid zone movement. [8]
The proto-evolutionary thinkers of the 18th and early 19th century had to invent terms to label their ideas, but it was first Joseph Gottlieb Kölreuter who used the term "transmutation" to refer to species who have had biological changes through hybridization. [3]
A study of four mammalian genera: Hyopsodus, Pelycodus, Haplomylus (three from the Eocene), and Plesiadapis (from the Paleocene) found that—through a large number of stratigraphic layers and specimen sampling—each group exhibited, "gradual phyletic evolution, overall size increase, iterative evolution of small species, and character ...
Rapid sympatric speciation can take place through polyploidy, such as by doubling of chromosome number; the result is progeny which are immediately reproductively isolated from the parent population. New species can also be created through hybridization, followed by reproductive isolation, if the hybrid is favoured by natural selection.
There is some evidence of adaptive evolution in genes linked to brain development, but some of these genes are often associated with diseases, e.g. microcephaly (see Table 2). However, there is a particular interest in the search for adaptive evolution in brain genes, despite the ethical issues surrounding such research.
Eukaryote hybrid genomes result from interspecific hybridization, where closely related species mate and produce offspring with admixed genomes.The advent of large-scale genomic sequencing has shown that hybridization is common, and that it may represent an important source of novel variation.
Fluorescence in situ hybridization (FISH) is a laboratory method used to detect and locate a DNA sequence, often on a particular chromosome. [4]In the 1960s, researchers Joseph Gall and Mary Lou Pardue found that molecular hybridization could be used to identify the position of DNA sequences in situ (i.e., in their natural positions within a chromosome).
The Baldwin effect compared to Lamarck's theory of evolution, Darwinian evolution, and Waddington's genetic assimilation. All the theories offer explanations of how organisms respond to a changed environment with adaptive inherited change. In evolutionary biology, the Baldwin effect describes an effect of learned behaviour on evolution.