Syngameon
From Wikipedia, the free encyclopedia
Syngameon refers to groups of taxa that frequently engage in natural hybridization and lack strong reproductive barriers that prevent interbreeding.[1][2] Syngameons are more common in plants than animals, with approximately 25% of plant species and 10% of animal species producing natural hybrids.[3] The most well known syngameons include irises of the California Pacific Coast and white oaks of the Eastern United States.[2][4] Hybridization within a syngameon is typically not equally distributed among species and few species often dominate patterns of hybridization.[3]
The term syngameon comes from the root word syngamy coined by Edward Bagnall Poulton to define groups that freely interbreed.[5] He also coined the word asyngamy referring to groups that do not freely interbreed (with the substantive noun forms Syngamy and Asyngamy).[5] The term syngameon was first used by Johannes Paulus Lotsy, who used it to describe a habitually interbreeding community that was reproductively isolated from other habitually interbreeding communities.[6] Syngameon was used interchangeably with the term species to describe groups of closely related individuals that interbreed to varying degrees.[5] A more specific definition of syngameon has been given to groups of taxa that frequently engage in natural hybridization and lack strong morphological differences that could be used to define them.[1][2] Taxa in syngameons may have separate species names, but evolutionary biologists often suggest they should be treated as a single species.[1] Variation among species within a syngameon can be due to a number of factors related to their biogeography, ecology, phylogeny, reproductive biology, and genetics.[3]
Coenospecies
The terms coenospecies and syngameons are both used to describe clusters of lineages that are morphologically distinct and lack strong isolation mechanisms.[1] Coenospecies, first coined by Göte Turesson in 1922,[7] refers to the total sum of possible combinations in a genotype compound, which includes hybridization that occurs both naturally and artificially.[7] Coenospecies is often used to describe lineages that can be crossed under cultivation and only a few species pairs are found to form natural hybrids, whereas syngameons refer to species where extensive evidence of natural hybridization occurs.[8][2] In this sense, definitions of syngameon and coenospecies correspond to the two different definitions of the Biological Species Concept proposed by Ernst Mayr; syngameon is consistent with “actually” interbreeding species, while coenospecies is consistent with “actually or potentially” interbreeding species.[1] The term ecospecies is considered a subdivision of coenospecies that refers to the genotypes within a coenospecies that hybridize and produce viable, fertile offspring.[7]