Cryptic species and phylogeographical structure in the tree Cedrela odorata L. throughout the Neotropics (original) (raw)
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Forest Ecology and Management, 2008
Cedrela odorata L., one of the most important neotropical timber species, is threatened by deforestation and unsustainable logging in many parts of its natural range. Information on patterns of genetic variation is useful in informing both reforestation and genetic conservation activities. However, to date, no such information is available in Peru or elsewhere in South America. In the present study, genetic diversity between and within nine Peruvian populations of the species, based on amplified fragment length polymorphism (AFLP) markers, is reported. Overall diversity level was high (Ht = 0.22), as expected for a widespread, long-lived tropical species, and consistent with previous studies carried out in Central America. Levels of intrapopulation diversity were higher than those previously reported for the species (Hs = 0.13–0.21). Analysis of molecular variation revealed genetic differences between two population groups located on different rivers and between populations located on the same rivers. Differences between groups were greater than those within groups. Genetic and geographical distances were significantly correlated. The relatively strong genetic differences between populations may be related to the riparian, essentially one-dimensional spatial distribution pattern of the populations studied. No difference was found in percentage of polymorphic loci between relatively undisturbed and logged populations. The existence of appreciable genetic differentiation over a relatively small part of the species range in the Peruvian Amazon suggests the need for caution in use of seed outside its zone of origin. For genetic conservation purposes, it would probably be prudent to sample (ex situ) or conserve (in situ) populations in each of the major watersheds of the Peruvian Amazon.
Phytotaxa
A new Cedrela (Meliaceae) species, Cedrela angusticarpa, is described through a combination of taxonomic, morphological, and molecular analyses. Cedrela kuelapensis, originally described as an endemic species of northern Peru, is also reported here as a new record for Ecuador. Cedrela angusticarpa has oblong or oblong-lanceolate glabrous leaflets, rounded at the base. Inflorescences are up to 70 cm long, and flowers present a cupuliform calyx with five regular teeth. Fruits are narrowly obovoid capsules. Through molecular analyses using nine microsatellite loci, it is evident that samples from C. angusticarpa form their own genetic cluster when compared to the most morphologically similar species, C. odorata, suggesting that they belong to a new separate species. Additionally, here we report that C. angusticarpa has a very narrow geographic range, recorded between 550 and 1300 m in elevation, and restricted to the relatively small areas of northwestern Ecuador. Climatic niche modell...
Tropical Plant Biology, 2010
Big-leaf mahogany (Swietenia macrophylla King) is one of the most valuable and overharvested timber trees of tropical America. In order to better characterize geographic patterns of genetic variation, we performed a phylogeographic analysis of S. macrophylla based on six polymorphic chloroplast genome simple sequence repeat loci (cpSSRs) analyzed in 16 populations (N = 245 individuals) distributed across Central America and the Brazilian Amazon. Of the 31 total cpDNA haplotypes identified, 16 occurred in Central America and 15 in Amazonia with no single haplotype shared between the two regions. Populations from Central America showed moderate differentiation (F ST = 0.36) while within population genetic diversity was generally high (mean Nei’s H E = 0.639). In contrast, the Amazonian populations were strongly differentiated (F ST = 0.91) and contained relatively low genetic diversity (mean H E = 0.176), except for one highly diverse population (H E = 0.925) from eastern Amazonia. Spatial analysis of molecular variance (SAMOVA) identified a single Central American phylogroup and four Amazonian phylogroups, indicating stronger phylogeographic structure within Amazonia. The results demonstrate distinctive regional patterns of S. macrophylla differentiation, and the first evidence of a strong phylogeographic break between Central American and South American mahogany populations. We suggest that the frequent occurrence of hurricanes in Central America, the differences in the glacial histories and in the duration and intensity of anthropogenic disturbance during the late Holocene may have played important roles in the geographic structuring of cpDNA lineages in the two regions. The high private haplotype diversity in Brazilian populations suggests that cpSSRs can be used as DNA barcodes for regional timber certification.