Loss of genetic variation at microsatellite loci in hatchery produced abalone in Australia (Haliotis rubra) and South Africa (Haliotis midae)

Aquaculture ◽  
2004 ◽  
Vol 233 (1-4) ◽  
pp. 109-127 ◽  
Author(s):  
B. Evans ◽  
J. Bartlett ◽  
N. Sweijd ◽  
P. Cook ◽  
N.G. Elliott
Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 147-157 ◽  
Author(s):  
Arjun Sivasundar ◽  
Jody Hey

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.


Author(s):  
Carol Simon ◽  
Guillermo San Martín ◽  
Georgina Robinson

Two new species of South African Syllidae of the genusSyllisLamarck, 1818 are described.Syllis unzimasp. nov. is characterized by having unidentate compound chaetae with long spines on margin, a characteristic colour pattern and its reproduction by vivipary. Vivipary is not common among the polychaetes, but most representatives occur in the family Syllidae Grube, 1850 (in five otherSyllisspecies, two species ofDentatisyllisPerkins, 1981 and two species ofParexogoneMesnil & Caullery, 1818).Syllis unzimasp. nov. differs from the other viviparous species in having large broods (>44 juveniles) which develop synchronously. Development of the juveniles is similar to that of free-spawningSyllisspecies, but the appearance of the first pair of eyespots and the differentiation of the pharynx and proventricle occur later inS. unzima.Syllis amicarmillarissp. nov., is characterized by having an elongated body with relatively short, fusiform dorsal cirri and the presence of one or two pseudosimple chaeta on midbody parapodia by loss of blade and enlargement of shaft.Syllis unzimasp. nov. was found in high densities on culturedHolothuria scabraJaeger, 1833 with single specimens found on a culturedCrassostrea gigasThunberg, 1793 and on coralline algae, respectively, whileS. amicarmillariswas found mainly in sediment outside an abalone farm and less frequently on culturedHaliotis midaeLinnaeus, 1758. We discuss the possible benefits of the association withH. scabratoS. unzimasp. nov.


2010 ◽  
Vol 41 (3) ◽  
pp. 332-333 ◽  
Author(s):  
R. Slabbert ◽  
J. Hepple ◽  
A. Venter ◽  
S. Nel ◽  
L. Swart ◽  
...  

Author(s):  
J. Albertyn ◽  
K.M. Tajbhai ◽  
R.R. Bragg

Psittacine beak and feather disease (PBFD) is a common disease of the psittacine species and is caused by the psittacine beak and feather disease virus (PBFDV). In this study the occurrence of the disease in ring-neck parakeets and budgerigars in South Africa suffering from feathering problems, using polymerase chain reaction as a diagnostic test was investigated. The genetic variation between viral isolates was also studied. Results indicate that PBFDV can be attributed to being the cause of feathering problems in some of the ring-neck parakeets and budgerigars in South Africa. Genetic variation of isolates occurs between species and individuals. A cheap and easy to use method of blood sample collection on filter paper for diagnostic purposes was also evaluated. It proved to be less stressful to the birds and did not inhibit further processes.


Aquaculture ◽  
2011 ◽  
Vol 315 (3-4) ◽  
pp. 187-195 ◽  
Author(s):  
B.M. Macey ◽  
K.W. Christison ◽  
A. Mouton
Keyword(s):  

2019 ◽  
pp. 289-293
Author(s):  
Svetlana Gorislavets ◽  
Vitalii Volodin ◽  
Gennadii Spotar ◽  
Valentina Risovannaya ◽  
Yakov Alekseev

Обязательными условиями успешного сохранения и использования различных сортов сельскохозяйственных культур является идентификация и контроль генетической изменчивости сортов, для изучения которой используются различные методы, в том числе методы молекулярно-генетического анализа. В связи с быстрым развитием селекции, ежегодно появляются десятки новых сортов винограда, требующих паспортизации. Молекулярные маркеры могут способствовать подбору родительских пар для скрещивания, повышению точности и ускорению селекционного процесса, так как идентификация исходного материала с использованием молекулярных маркеров и анализ результатов скрещивания могут быть выполнены в достаточно короткий период. К наиболее информативным молекулярным маркерам относятся микросателлитные маркеры, основанные на анализе простых повторяющихся повторов (simple sequence repeats, SSR). Анализ полиморфизма SSR локусов позволяет изучить генетическую изменчивость сельскохозяйственных культур на уровне генома. Цель нашего исследования - генотипирование, оценка аллельного разнообразия и ДНК-паспортизация ряда сортов винограда селекции Института «Магарач» на основе SSR анализа. Основной метод, использованный в работе, - полимеразная цепная реакция (ПЦР) и фрагментный анализ продуктов ПЦР на генетическом анализаторе ABI 3130. В результате фрагментного анализа были генотипированы 8 селекционных сортов Института «Магарач» по 9 ядерным микросателлитным локусам (nSSR). Размеры аллелей оценены с помощью программы Gene Mapper v. 4.0. Полиморфизм микросателлитных локусов и генетическое разнообразие рассчитано с использованием программы Popgene (v. 1.32). Сравнительный анализ nSSR профилей ДНК изученных сортов позволил установить, что все сорта имеют уникальные профили. Всего идентифицировано 69 аллелей, среднее число аллелей - 7,67 аллелей/локус. На основании размеров аллелей составлены индивидуальные молекулярно-генетические паспорта в соответствии с международными стандартами.Identification and control of genetic variation of different varieties of agricultural crops enter as prerequisites for their efficient conservation and use. Genetic variation is investigated by means of a wide set of methods, including those relying on molecular-genetic analysis. Every year, dozens of new breedings of grapevine come into being, and their passportization is necessary. Molecular markets can promote selection of parent pairs for crossing, improve efficiency of breeding and accelerate the process as enable both identification of the initial material and analysis of crossing results to be done in a sufficiently short period of time. The highest information value is associated with microsatellite markers consisting of simple sequence repeats (SSR). Analysis of polymorphism of SSR loci allows to investigate genetic variation of agricultural crops at the level of genome. The goals of the study were to conduct genotyping of a number of grape breedings developed by the Institute Magarach, to assess their allelic diversity and to achieve DNA passportization based on SSR analysis. Polymerase chain reaction (PCR) and fragment analysis of PCR products with the use of a genetic analizer ABI 3130 were the main methods the study relied upon. As a result of the aforesaid analysis, eight new breedings of the Institute were genotyped for nine nuclear microsatellite loci (nSSR). The sizes of alleles were assessed using Gene Mapper v. 4.0 software. Popgene (v. 1.32) software was used to calculate polymorphism of microsatellite loci and genetic diversity. A comparative nSSR-analysis of DNA-profiles of the study varieties indicated that all of them had unique profiles. A total of 69 alleles were identified, with 7.67 alleles per locus on an average. Based on the sizes of the alleles, individual molecular-genetic passports of the varieties were made, in accordance with international standards.


The Condor ◽  
2007 ◽  
Vol 109 (4) ◽  
pp. 954-962
Author(s):  
Robert C. Fleischer ◽  
Beth Slikas ◽  
Jon Beadell ◽  
Colm Atkins ◽  
Carl E. McINTOSH ◽  
...  

Abstract The Millerbird (Acrocephalus familiaris) is an endemic Northwestern Hawaiian Islands reed warbler that existed until about 1923 on Laysan Island (A. f. familiaris) and currently occurs in a small population on Nihoa Island (A. f. kingi). The two populations are described as separate subspecies or species on the basis of size and plumage differences. We assessed genetic variation in blood samples from 15 individuals in the modern Nihoa population using approximately 3000 base pairs (bp) of mitochondrial DNA (mtDNA) sequence and 14 microsatellite loci. We also obtained up to 1028 bp of mtDNA sequence from the fragmented DNA of museum specimens of three birds collected on Nihoa in 1923 and five birds collected on Laysan in 1902 and 1911 (ancient samples). Genetic variation in both marker types was extremely low in the modern Nihoa population (nucleotide diversity [π]  =  0.00005 for mtDNA sequences; observed heterozygosity was 7.2% for the microsatellite loci). In contrast, we found three mtDNA haplotypes among the five Laysan individuals (π  =  0.0023), indicating substantially greater genetic variation. The Nihoa and Laysan taxa differed by 1.7% uncorrected mtDNA sequence divergence, a magnitude that would support designation at the subspecies, and perhaps species, level relative to other closely related Acrocephalus species pairs. However, in light of strong ecological similarity between the two taxa, and a need to have additional populations to prevent extinction from stochastic effects and catastrophes, we believe these genetic differences should not deter a potential translocation of individuals from Nihoa to Laysan.


2015 ◽  
Vol 53 (4) ◽  
pp. 447-453 ◽  
Author(s):  
Steffen Heelemann ◽  
Veronika Bäuerlein ◽  
Cornelia B. Krug ◽  
Karen J. Esler ◽  
Peter Poschlod ◽  
...  

2003 ◽  
Vol 38 (1) ◽  
pp. 109-117 ◽  
Author(s):  
Mosa G.A. Lesia ◽  
Margaretha D. Hofmeyr ◽  
Maria E. D΄Amato

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