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Sympatric speciation is the formation of two or more descendant species from a single ancestral species all occupying the same geographic location. Often-cited examples of sympatric speciation are found in insects that become dependent on different host plants in the same area. [38] [39]
Controversy exists as to whether Charles Darwin recognized a true geographical-based model of speciation in his publication On the Origin of Species. [5] In chapter 11, "Geographical Distribution", Darwin discusses geographic barriers to migration, stating for example that "barriers of any kind, or obstacles to free migration, are related in a close and important manner to the differences ...
A rare example of sympatric speciation in animals is the divergence of "resident" and "transient" orca forms in the northeast Pacific. [26] Resident and transient orcas inhabit the same waters, but avoid each other and do not interbreed. The two forms hunt different prey species and have different diets, vocal behaviour, and social structures.
In animals, ecotypes owe their differing characteristics to the effects of a very local environment which has been hypothesized to lead to speciation through the emergence of reproductive barriers. [ 12 ] [ 13 ] [ 14 ] Therefore, ecotypes have no taxonomic rank .
Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other' and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model [1]: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. [1] An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation .
Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. According to modern evolutionary biology, all living beings could be descendants of a unique ancestor commonly referred to as the last universal common ancestor (LUCA) of all life on Earth. [1] [2] [3] [4]
However, there are numerous examples of closely related, ecologically similar species (e.g., Albinaria land snails on islands in the Mediterranean, [7] Batrachoseps salamanders from California, [8] and certain crickets [9] and damselflies [10]), which is a pattern consistent with the possibility of nonecological speciation.