Nucleotide divergence between populations of trembling aspen (Populus tremuloides) estimated with RAPDs

Abstract

In the present study, a total of 142 trees sampled from five populations of trembling aspen (Populus tremuloides Michx.) in Alberta was analyzed by the polymerase chain reaction (PCR) with five random oligonucleotide primers. Null-allele frequencies of 28 putative RAPD loci were estimated using the given departure from Hardy-Weinberg equilibrium (F1S) previously estimated with isozyme markers for the same population. Nucleotide divergence between populations was then estimated in a fashion similar to restriction-fragment data, but considering the dominance of the RAPDs. The average of nucleotide divergence between populations was in the order of 0.0005 and nucleotide divergence were found to be highly correlated with geographic distance. The results suggest that isolation by distance may be an important factor in the genetic differentiation of trembling aspen.

Empirical assessment of allozyme and RAPD variation in Pinus sylvestris (L.) using haploid tissue analysis

“…It has been suggested that because of the generally neutral character of allozyme and RAPD markers potential deviations from HWE should affect both types of markers in a similar way (Chong et al, 1994). Results of the present study provide the first empirical evidence for this suggestion.…”

“…In plants, RAPDs generally show similar or higher levels of polymorphism than other types of markers (Liu & Fumier, 1993;Chong et al, 1994;Wu et al, 1995). Our present measurements of genetic variability based on the direct RAPD frequencies are concordant with these results.…”

“…In this approach it is assumed that the population under study is in a Hardy-Weinberg equilibrium (HWE). When data for codominant markers are available, the estimated RAPD allele frequency can be corrected for potential deviations from HWE (Chong et a!., 1994). Studies employing allozymes suggest that wind-pollinated conifers, including Pinus sylvestris (L.), generally show only modest departures from HWE for this type of marker (Szmidt & Muona, 1985;Plessas & Strauss, 1986).…”

“…Another issue addressed in several recent studies on RAPD variation is the relative merit of RAPD data as compared to other types of genetic markers such as allozymes and RFLPs (Liu & Fumier, 1993;Chong et a!., 1994;Thormann et a!., 1994;Wu et a!., 1995). For instance, it has been suggested that RAPDs may be more useful for detecting population differentiation than allozymes (Wu et a!., 1995).…”

Diversidade genética de cultivares de alho avaliada por marcadores RAPD

“…Considerando que o presente trabalho buscou estimar a diverdidade genética entre indivíduos com sistema reprodutivo assexuado e, portanto, sem capacidade para recombinação genética, tal polimorfismo pode ser considerado alto se comparado com os relatados em alguns trabalhos utilizando marcadores RAPD: 3,0 para Araucária angustifólia (STEFENON, 2003); 1,8 para Pinus palustris (KUBISIAK et al, 1995) e 3,0 para Lycopersicon esculentum (RUS-KORTEKAAS et al, 1994). Entretanto, é baixo quando comparado com outras espécies: 4,2 para Eucalyptus urophylla (PIGATO & LOPES, 2001); 5,0 para Picea abies (BUCCI & MENOZZI, 1995) e 5,6 para Populus tremuloides (CHONG et al, 1994). Tal superioridade no grau de polimorfismo é compreensível, uma vez que estas espécies são férteis, predominando na sua maioria um sistema reprodutivo com fecundação cruzada, o que possibilita um maior nível de heterozigose nessas plantas.…”