Genetic variation in Costa Rican populations of the tropical timber species Cedrela odorata L., assessed using RAPDs

Abstract

Cedrela odorata L. (Spanish cedar), an economically important timber species native to the American tropics, is the focus of increasing conservation concern due to high rates of deforestation within its native range. To assess the extent of the genetic diversity within and between populations of this species, samples were obtained from 10 widely dispersed populations within Costa Rica and analysed for random amplified polymorphic DNA (RAPD) variation. Fourteen 10‐mer primers were used to generate 97 polymorphic RAPD bands. Presence/absence data for all bands were subjected to a pairwise genetic distance analysis, according to Jaccard's coefficient, then neighbour‐joining cluster analysis was performed on these distances, as was an analysis of molecular variance (AMOVA), to assess levels of differentiation between populations and regions, and Shannon's Diversity Index was used to quantify levels of diversity within and between populations. Results indicated highly significant genetic differentiation (P < 0.004, AMOVA) between populations originating from the North Pacific and Atlantic/South Pacific regions of Costa Rica, with 35.3% of the total variation attributable to a difference between these areas. Little differentiation was recorded between populations from within the same region (P= 0.757, AMOVA), and 65.1% of the total variance was attributable to variation within populations. Estimated values for within‐population diversity, calculated as Hpop/Hsp by means of Shannon's Diversity Index, were found to vary greatly between primers, but the overall within‐population component of genetic diversity was 0.45. Possible reasons for the high degree of intraspecific genetic variation within this species are discussed and the implications of these results for the conservation and use of its genetic resources are described.

Genetic structure of natural Eugenia dysenterica DC (Myrtaceae) populations in northeastern Goiás, Brazil, accessed by morphological traits and RAPD markers

“…The analysis of molecular variance indicated a total variance of 0.43456. This value is similar to that obtained by Gillies et al (1997) who analyzed Cedrela odorata populations in Costa Rica, with the same type of marker. High levels of total variance are also reported for temperate climate species (Yeh et al, 1995;Liao and Hsiao, 1998).…”

Genetic differentiation and diversity analysis of medicinal tree Syzygium cumini (Myrtaceae) from ecologically different regions of India

“…28.8 in Pinus chiapensis and Syzygium travancoricum. Our results of polymorphism in primers (50-100 %) matched with earlier studies (Gillies et al, 1997;Kant et al, 2006) and showed that species diversity was not low and it should be able to fit in the environmental variation (Fu et al, 2003). Primer 3 and 5 gave single band, which might be explained as RAPD markers tag specific regions in the genome.…”

Diversidade genética de acessos do banco de germoplasma de mangaba em Sergipe

“…Esses valores podem ser atribuídos à fragmentação das áreas em que foram obtidos, com forte pressão de seleção antrópica. A comparação com o índice de Shannon encontrado em outros estudos é limitada, pois abordagens diferentes podem ter sido utilizadas para calculá-lo (Gillies et al, 1997). Assim, os resultados observados, neste trabalho, podem contribuir para grupos de pesquisa que utilizem padrões similares.…”