Geographic pattern of genetic diversity in natural populations of Rosewood (Aniba rosaeodora), in the Central Amazonia

Abstract

Rosewood (Aniba rosaeodora Ducke, lauraceae) is an amazonian evergreen tree and a source of the purest linalool, the main component of its essential oil, which is very valuable in the international perfumery market. after decades of over-exploitation it is currently considered as threatened. We evaluated the genetic diversity and its distribution in four populations in Central amazonia. thirty-five reliable RaPD markers were generated, of which 32 were polymorphic (91.4%). variation was higher within the populations (76.5%; p < 0.0001) and geographic distribution contributed to population differentiation (23.4%; p < 0.0001). the amazon River had a small influence on gene flow (3.3%; p < 0.0001), but we identified evidence of gene flow across the river. there were significant differences in marker frequencies (p < 0.05), in agreement with the low gene flow (Nm = 2.02). the correlation between genetic distance and gene flow was -0.95 (p = 0.06) and between geographic distance and gene flow was -0.78 (p = 0.12). there was a geographic cline of variability across an east-West axis, influenced as well by the amazon River, suggesting the river could be a barrier to gene flow. although threatened, these Rosewood populations retain high diversity, with the highest levels in the manaus population, which has been protected for over 42 years in a Reserve.Keywords: RaPD, linalool, gene flow, amazon Rainforest.Padrão geográfico de diversidade genética em populações naturais de Pau-rosa (Aniba rosaeodora), na Amazônia Central resumo o Pau-rosa (Aniba rosaeodora Ducke, lauraceae) é uma árvore amazônica fonte do mais puro linalol, o qual é o principal componente do seu óleo essencial e muito valioso no mercado internacional de perfumaria. após várias décadas de intensa exploração, a espécie foi levada à categoria de ameaçada de extinção. Quatro populações naturais distribuídas na bacia amazônia Central foram avaliadas quanto ao nível e a distribuição da diversidade genética. trinta e cinco marcadores RaPD reprodutíveis foram gerados, dos quais 32 foram polimórficos (91,4%). a diversidade foi maior dentro das populações (76,5%; p < 0,0001) e a distribuição geográfica contribuiu para a diferenciação entre as populações (23,4%; p < 0,0001). a amova indicou que pode haver uma influência parcial do Rio amazonas no fluxo gênico (3,3%; p < 0,0001), mas foram identificadas evidências de fluxo gênico atravessando o rio. Houve diferenças significativas nas freqüências dos marcadores (p < 0,05) e o fluxo gênico estimado foi relativamente baixo (Nm = 2,02). a correlação entre a distância genética e o fluxo gênico foi de -0,95 (p = 0,06) e para a distância geográfica e o fluxo gênico foi de -0,78 (p = 0,12). Houve um padrão geográfico de variabilidade ao longo do eixo leste -oeste, influenciado também pelo Rio amazonas, o que sugere que o rio poderia funcionar como uma barreira para o fluxo gênico. apesar de ameaçadas, estas populações de Pau-rosa possuem alta diversidade, com o maior valor na população de manaus, que vem sendo prot...

Genetic diversity in rosewood saplings (Aniba rosaeodora ducke, Lauraceae): an ecological approach

“…In the current study planted Rosewood trees had a high seed removal rate, promoted by seed dispersal agents, and in native population a very high gene flow among the subgroups . This also corroborates to high RAPD diversity in natural adults populations of Rosewood (Santos et al, 2008), as well high polymorphism identified in Rosewood´s microsatellites locis (Angrizani et al, 2008). These results imply that seed removals might play an important role in gene movement in native Rosewood population, but we were unable to assess its total contribution since rates of gene flow via pollen flow were not evaluated.…”

“…As a result, its population has decreased to the point where the species is at risk of extinction (IBAMA, 1992). Nonetheless, high RAPD diversity in exploited natural populations of Rosewood was showed recently by Santos et al (2008). Has the low population densities of Rosewood in exploited forests have resulted in reduced seed set?…”

Gene dispersal via seeds and pollen and their effects on genetic structure in the facultative-apomictic Neotropical tree Aspidosperma polyneuron

“…These studies are keys to developing strategies for conservation genetics of the remaining populations of endangered species. Genetics studies based on genetic markers, such as microsatellite markers, can help to illuminate such ecological and genetic processes in plant populations (Burczyk et al, 2004;Ashley, 2010). To assess these ecological and genetic processes using genetic markers, samples from adults, open-pollinated seeds, and/or regenerants (seedlings and juveniles) of the focus species must be used along with techniques such as parentage analysis (Burczyk et al, 2004).…”

“…Genetics studies based on genetic markers, such as microsatellite markers, can help to illuminate such ecological and genetic processes in plant populations (Burczyk et al, 2004;Ashley, 2010). To assess these ecological and genetic processes using genetic markers, samples from adults, open-pollinated seeds, and/or regenerants (seedlings and juveniles) of the focus species must be used along with techniques such as parentage analysis (Burczyk et al, 2004). Paternity analysis based on open-pollinated seeds enables the investigation of effective pollen flow and dispersal patterns, while maternity and paternity analysis based on regenerants enables the investigation of realized pollen and seed flow and dispersal patterns (Burczyk et al, 2004;Ashley, 2010).…”

“…To assess these ecological and genetic processes using genetic markers, samples from adults, open-pollinated seeds, and/or regenerants (seedlings and juveniles) of the focus species must be used along with techniques such as parentage analysis (Burczyk et al, 2004). Paternity analysis based on open-pollinated seeds enables the investigation of effective pollen flow and dispersal patterns, while maternity and paternity analysis based on regenerants enables the investigation of realized pollen and seed flow and dispersal patterns (Burczyk et al, 2004;Ashley, 2010). Furthermore, genetics studies in forest remnants can help provide insight into the mechanisms that maintain apomictic populations, such as A. polyneuron.…”