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Panmixia (or panmixis) means random mating.[1][2]
A panmictic population is one where all individuals are potential partners. This assumes that there are no mating restrictions, neither genetic nor behavioural, upon the population, and that therefore all recombination is possible. The Wahlund effect assumes that the overall population is panmictic.[3]
In genetics, random mating[4] involves the mating of individuals regardless of any physical, genetic, or social preference. In other words, the mating between two organisms is not influenced by any environmental, hereditary, or social interaction. Hence, potential mates have an equal chance of being selected. Random mating is a factor assumed in the Hardy-Weinberg principle and is distinct from lack of natural selection: in viability selection for instance, selection occurs before mating.
Contents
1Description
2Background information
3Panmictic species
4Related experiments and species
5See also
6References
Description
In simple terms, panmixia (or panmicticism) is the ability of individuals in a population to interbreed without restrictions; individuals are able to move about freely within their habitat, possibly over a range of hundreds to thousands of miles, and thus breed with other members of the population.
To signify the importance of this, imagine several different finite populations of the same species (for example: a grazing herbivore), isolated from each other by some physical characteristic of the environment (dense forest areas separating grazing lands). As time progresses, natural selection and genetic drift will slowly move each population toward genetic differentiation that would make each population genetically unique (that could eventually lead to speciation events or extirpation).
However, if the separating factor is removed before this happens (e.g. a road is cut through the forest), and the individuals are allowed to move about freely, the individual populations will still be able to interbreed. As the species's populations interbreed over time, they become more genetically uniform, functioning again as a single panmictic population.
In attempting to describe the mathematical properties of structured populations, Sewall Wright proposed a "factor of Panmixia" (P) to include in the equations describing the gene frequencies in a population, and accounting for a population's tendency towards panmixia, while a "factor of Fixation" (F) would account for a population's departure from the Hardy-Weinberg expectation, due to less than panmictic mating. In this formulation, the two quantities are complementary, i.e. P = 1 - F. From this factor of fixation, he later developed the F statistics.
Background information
In a panmictic species, all of the individuals of a single species are potential partners, and the species gives no mating restrictions throughout the population.[5] Panmixia can also be referred to as random mating, referring to a population that randomly chooses their mate, rather than sorting between the adults of the population.[6]
Panmixia allows for species to reach genetic diversity through gene flow more efficiently than monandry species.[7] However, outside population factors, like drought and limited food sources, can affect the way any species will mate.[8] When scientist examine species mating to understand their mating style, they look at factors like genetic markers, genetic differentiation, and gene pool.[9]
Panmictic species
Pantala flavescens is considered as a global panmictic population.
A panmictic population of Monostroma latissimum, a marine green algae, shows sympatric speciation in southwest Japanese islands. Although panmictic, the population is diversifying.[10] Dawson's Burrowing bee, Amegilla dawsoni, may be forced to aggregate in common mating areas due to uneven resource distribution in its harsh desert environment.[11]Pantala flavescens should be considered as a global panmictic population.[12]
Related experiments and species
Anguilla rostrate, or the American eel, exhibits panmixia throughout the entire species. This allows the eel to have phenotypic variation in their offspring and survive in a wide range of environmental conditions[13]
In 2016, BMC Evolutionary Biology conducted a study on Pachygrapsus marmoratus, the marbled crab, marking them as panmictic species. The study claimed that the crabs' mating behavior is characterized by genetic differentiation due to geographic breaks across its distribution range and not panmixia[14]
In a heterogeneous environment such as the forests of Oregon, United States, Douglas squirrels (Tamiasciurus douglasii) exhibit local patterns of adaptation. In a study conducted by Chaves (2014) a population along an entire transect was found to be panmictic. Traits observed in this study included skull shape, fur color, etc.
Swordfish based in the Indian Ocean (Xiphias gladius) have been found to be a single panmictic population. Markers used in the study carried out by Muths et al (2013) found large spatial and temporal homogeneity in genetic structure satisfactory in order to consider the swordfish a singular panmictic population.
See also
Assortative mating (one form of non-random mating)
Population genetics
Monogamy: A mating system in which one male mates with just one female, and one female mates with just one male, in breeding season
Polygyny: A mating system in which a male fertilizes the eggs of several partners in breeding season
Sexual selection: A form of natural selection that occurs when individuals vary in their ability to compete with others for mates or to attract members of the opposite sex
Fitness: A measure of the genes contributed to the next generation by an individual, often stated in terms of the number of surviving offspring produced by the individual
References
^King C and Stanfield W.D. 1997. Dictionary of genetics. Oxford. "Panmixia (panmixis): random mating as contrasted with assortative mating."
^Merriam-Webster Medical Dictionary. "Panmixia: Random mating within a breeding population."
^Gayon, Jean; Cobb, Matthew (1998), Darwinism's Struggle for Survival: Heredity and the Hypothesis of Natural Selection, Cambridge University Press, p. 158, ISBN 978-0-521-56250-8
^Choudhuri, Supratim (2014-05-09). Bioinformatics for Beginners: Genes, Genomes, Molecular Evolution, Databases and Analytical Tools. ISBN 9780124105102.
^"Of Terms in Biology: Panmictic".
^"Welcome to NOAA | NOAA Fisheries".
^Beveridge, M.; Simmons, L. W. (2006). "Panmixia: An example from Dawson's burrowing bee (Amegilla dawsoni) (Hymenoptera: Anthophorini)". Molecular Ecology. 15 (4): 951–7. doi:10.1111/j.1365-294X.2006.02846.x. PMID 16599959.
^Beveridge, M.; Simmons, L. W. (2006). "Panmixia: An example from Dawson's burrowing bee (Amegilla dawsoni) (Hymenoptera: Anthophorini)". Molecular Ecology. 15 (4): 951–7. doi:10.1111/j.1365-294X.2006.02846.x. PMID 16599959.
^Pujolar, J. M. (2013). "Conclusive evidence for panmixia in the American eel". Molecular Ecology. 22 (7): 1761–2. doi:10.1111/mec.12143. PMID 23620904.
^Bast, Felix; Kubota, Satoshi; Okuda, Kazuo (11 November 2014). "Phylogeographic assessment of panmictic Monostroma species from Kuroshio Coast, Japan, reveals sympatric speciation". Journal of Applied Phycology. 27 (4): 1725–1735. doi:10.1007/s10811-014-0452-x.
^Beveridge, Maxine; Simmons, Leigh W. (2006-04-01). "Panmixia: an example from Dawson's burrowing bee (Amegilla dawsoni) (Hymenoptera: Anthophorini)". Molecular Ecology. 15 (4): 951–957. doi:10.1111/j.1365-294X.2006.02846.x. ISSN 1365-294X. PMID 16599959.
^Daniel Troast, Frank Suhling, Hiroshi Jinguji, Göran Sahlén, Jessica Ware (2016). "A Global Population Genetic Study of Pantala flavescens". PLOS ONE. 11 (3): e0148949. Bibcode:2016PLoSO..1148949T. doi:10.1371/journal.pone.0148949. PMC 4775058. PMID 26934181.CS1 maint: Uses authors parameter (link)
^Côté, Caroline L.; Castonguay, Martin; Kalujnaia, Mcwilliam; Cramb, Gordon; Bernatchez, Louis (2014). "In absence of local adaptation, plasticity and spatially varying selection rule: A view from genomic reaction norms in a panmictic species (Anguilla rostrata)". BMC Genomics. 15: 403. doi:10.1186/1471-2164-15-403. PMC 4229938. PMID 24884429.
^Fratini, Sara; Ragionieri, Lapo; Deli, Temim; Harrer, Alexandra; Marino, Ilaria A. M.; Cannicci, Stefano; Zane, Lorenzo; Schubart, Christoph D. (2016). "Unravelling population genetic structure with mitochondrial DNA in a notional panmictic coastal crab species: Sample size makes the difference". BMC Evolutionary Biology. 16: 150. doi:10.1186/s12862-016-0720-2. PMC 4960869. PMID 27455997.
Elio. "Of Terms in Biology: Panmictic". Small Things Considered.
"Random Mating". NOAA.
Pujolar (2013). "Conclusive evidence for panmixia in the American eel". Mol Ecol. 22 (7): 1761–2. doi:10.1111/mec.12143. PMID 23620904.
Beveridge, Simmons (2006). "Panmixia: an example from Dawson's burrowing bee (Amegilla dawsoni) (Hymenoptera: Anthophorini". Mol Ecol. 15 (3): 951–7. doi:10.1111/j.1365-294X.2006.02846.x. PMID 16599959.
Muths, D., Le Couls, S., Evano, H., Grewe, P., & Bourjea, J. (2013). "Multi-Genetic Marker Approach and Spatio-Temporal Analysis Suggest There Is a Single Panmictic Population of Swordfish Xiphias gladius in the Indian Ocean". PLOS One. 8 (5): e63558. Bibcode:2013PLoSO...863558M. doi:10.1371/journal.pone.0063558. PMC 3661515. PMID 23717447.CS1 maint: Multiple names: authors list (link)
Fratini, S., Ragionieri, L., Deli, T., Harrer, A., Marino, I. A. M., Cannicci, S., … Schubart, C. D. (2016). "Unravelling population genetic structure with mitochondrial DNA in a notional panmictic coastal crab species: sample size makes the difference". BMC Evolutionary Biology. 16: 150. doi:10.1186/s12862-016-0720-2. PMC 4960869. PMID 27455997.CS1 maint: Multiple names: authors list (link)
Côté, C. L., Castonguay, M., Kalujnaia, M. S., Cramb, G., & Bernatchez, L. (2014). "In absence of local adaptation, plasticity and spatially varying selection rule: a view from genomic reaction norms in a panmictic species (Anguilla rostrata)". BMC Genomics. 15: 403. doi:10.1186/1471-2164-15-403. PMC 4229938. PMID 24884429.CS1 maint: Multiple names: authors list (link)
Chavez, A. S., & Kenagy, G. J. (2014). "Clinal colour variation within a panmictic population of tree squirrels, Tamiasciurus douglasii ( Rodentia: Sciuridae), across an ecological gradient". Biological Journal of the Linnean Society. 113 (2): 536. doi:10.1111/bij.12361.CS1 maint: Multiple names: authors list (link)
English Journal
High levels of interspecific gene flow in an endemic cichlid fish adaptive radiation from an extreme lake environment.
Ford AG1, Dasmahapatra KK2, Rüber L3, Gharbi K4, Cezard T4, Day JJ1.
Molecular ecology.Mol Ecol.2015 May 20. doi: 10.1111/mec.13247. [Epub ahead of print]
Studying recent adaptive radiations in isolated insular systems avoids complicating causal events and thus may offer clearer insight into mechanisms generating biological diversity. Here we investigate evolutionary relationships and genomic differentiation within the recent radiation of Alcolapia ci
Genomics.Genomics.2015 Apr;105(4):237-41. doi: 10.1016/j.ygeno.2015.01.002. Epub 2015 Jan 23.
Runs of homozygosity are common in European populations and are indicative of consanguinity, restricted population size and recessively inherited traits. Here, we map runs of homozygosity (ROHs) in an Irish case-control cohort for amyotrophic lateral sclerosis (ALS), a devastating neurological condi
Geographical segregation of Cryptosporidium parvum multilocus genotypes in Europe.
Cacciò SM1, de Waele V2, Widmer G3.
Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases.Infect Genet Evol.2015 Apr;31:245-9. doi: 10.1016/j.meegid.2015.02.008. Epub 2015 Feb 14.
Cryptosporidium parvum is a common enteric protozoan pathogen of humans and livestock. Multilocus genotyping based on simple sequence repeat polymorphisms has been used extensively to identify transmission cycles and to investigate the structure of C. parvum populations and of the related pathogen C
… The sub-structuring observed, along with the lack of panmixia in the populations, could have been due to low transmission levels at the time of sampling. …
Identification of the Male Parents of Half-sib Progeny from Japanese Black Pine (Pinus thunbergii Parl.) Clonal Seed Orchard using RAPD Markers
Goto Susumu,Miyahara Fumihiko,Ide Yuji
Breeding science 52(2), 71-77, 2002-06-00
… Mating with the clone deviated significantly from panmixia. … Deviations from panmixia have been caused by a difference in the distance between clones, variation in the amounts of pollen, and phenological synchrony between clones. …
Panmixia, Porto. 787 likes · 5 talking about this. Nasceu em 2003 como resultado das cumplicidades entre diversos criadores e agentes culturais da região do Porto (Amélia Lopes, Francisco Beja, José Carretas, Margarida ...
pan·mix·i·a / pænˈmɪk si ə / Show Spelled [pan-mik-see-uh] Show IPA noun Animal Behavior. random mating of individuals within a population, the breeding individuals showing no tendency to choose partners with particular traits. ...