A new index for estimating genetic recombination from chiasma distribution data
Chiasma frequency and position are good estimators of genetic recombination in a population. Darlington proposed a recombination index that consisted of the sum of the haploid number [n] and the average chiasma number per nucleus (x); this index (n+x) represents the average number of elements that s...
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_0018067X_v69_n5_p412_Colombo |
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todo:paper_0018067X_v69_n5_p412_Colombo2023-10-03T14:15:23Z A new index for estimating genetic recombination from chiasma distribution data Colombo, P.C. Chiasma distribution Genetic variability Recombination index Chiasma frequency and position are good estimators of genetic recombination in a population. Darlington proposed a recombination index that consisted of the sum of the haploid number [n] and the average chiasma number per nucleus (x); this index (n+x) represents the average number of elements that segregate independently, so that the number of possible gametes equals 2(n+x). Here a more accurate approach is intended by proposing an index that takes into account: (a) the proportional length of chromosomes and (b) the accurate position of chiasmata. (a) Let G be the product of 2(n)(Li), where L¡ is the proportional length of each chromosome; if every chromosome has the same length (L1 =L2 =… =Ln), then Li = 1/n, and G = 2n is the number of possible gametes. (a) Let G' be the product of 2(n +x)(Li); where L, here is the length of each one of the n+x chromosome regions that segregate independently. Note that if L1 = L2 =… = Ln and chiasmata are sited in the middle of each chromosome, Li = l/(n+x), G' = 2(n+x) is the possible number of gametes, and lg2G' = (n+x) is the Darlington index. It is then proposed that Ir = lg2G' is a more general index of recombination that represents something like an effective number of independently segregating units, weighted by their proportional lengths. A further improvement to this index (I'r) that renders less dispersed values is also worked out. The development of simulation programs and the study of real cases (v.gr. Leptysma argentina) demonstrated that the index of Darlington (a special case of Ir and I’r) is always an overestimation of the recombination level of a population. Hence indexes Ir and I’r are proposed for organisms that allow a reasonably accurate measurement of chiasma distribution. © The Genetical Society of Great Britain. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0018067X_v69_n5_p412_Colombo |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Chiasma distribution Genetic variability Recombination index |
| spellingShingle |
Chiasma distribution Genetic variability Recombination index Colombo, P.C. A new index for estimating genetic recombination from chiasma distribution data |
| topic_facet |
Chiasma distribution Genetic variability Recombination index |
| description |
Chiasma frequency and position are good estimators of genetic recombination in a population. Darlington proposed a recombination index that consisted of the sum of the haploid number [n] and the average chiasma number per nucleus (x); this index (n+x) represents the average number of elements that segregate independently, so that the number of possible gametes equals 2(n+x). Here a more accurate approach is intended by proposing an index that takes into account: (a) the proportional length of chromosomes and (b) the accurate position of chiasmata. (a) Let G be the product of 2(n)(Li), where L¡ is the proportional length of each chromosome; if every chromosome has the same length (L1 =L2 =… =Ln), then Li = 1/n, and G = 2n is the number of possible gametes. (a) Let G' be the product of 2(n +x)(Li); where L, here is the length of each one of the n+x chromosome regions that segregate independently. Note that if L1 = L2 =… = Ln and chiasmata are sited in the middle of each chromosome, Li = l/(n+x), G' = 2(n+x) is the possible number of gametes, and lg2G' = (n+x) is the Darlington index. It is then proposed that Ir = lg2G' is a more general index of recombination that represents something like an effective number of independently segregating units, weighted by their proportional lengths. A further improvement to this index (I'r) that renders less dispersed values is also worked out. The development of simulation programs and the study of real cases (v.gr. Leptysma argentina) demonstrated that the index of Darlington (a special case of Ir and I’r) is always an overestimation of the recombination level of a population. Hence indexes Ir and I’r are proposed for organisms that allow a reasonably accurate measurement of chiasma distribution. © The Genetical Society of Great Britain. |
| format |
JOUR |
| author |
Colombo, P.C. |
| author_facet |
Colombo, P.C. |
| author_sort |
Colombo, P.C. |
| title |
A new index for estimating genetic recombination from chiasma distribution data |
| title_short |
A new index for estimating genetic recombination from chiasma distribution data |
| title_full |
A new index for estimating genetic recombination from chiasma distribution data |
| title_fullStr |
A new index for estimating genetic recombination from chiasma distribution data |
| title_full_unstemmed |
A new index for estimating genetic recombination from chiasma distribution data |
| title_sort |
new index for estimating genetic recombination from chiasma distribution data |
| url |
http://hdl.handle.net/20.500.12110/paper_0018067X_v69_n5_p412_Colombo |
| work_keys_str_mv |
AT colombopc anewindexforestimatinggeneticrecombinationfromchiasmadistributiondata AT colombopc newindexforestimatinggeneticrecombinationfromchiasmadistributiondata |
| _version_ |
1807318450955091968 |