Assessment of genetic diversity using RAPD analysis in a germplasm collection of sea buckthorn

Random amplified polymorphic DNA (RAPD) markers were used to characterize a part of a sea buckthorn gene bank collected for plant breeding purposes. Molecular markers were generated in 55 cultivars and accessions, representing five subspecies of Hippophae rhamnoides L. and intraspecific hybrids between different subspecies. Sixty-three markers were used to generate a Dice's similarity coefficient matrix of pairwise comparisons between individual RAPD profiles. Cluster (UPGMA) and principal co-ordinate analyses, based on this matrix, revealed clustering of plants into groups which generally correspond to their taxonomic classification or geographic origin. The analysis of molecular variance (AMOVA) was found useful for estimating components of genetic variation between and within taxonomic and geographic groups of accessions and cultivars. Whereas both alternatives for grouping the material (taxonomic or geographic origin) resulted in significant between-group variation, the major part of molecular variance (approximately 75%) was still attributed to variation within groups. We conclude that the RAPD analysis is useful for clarification of taxonomic and geographic origin of accessions and cultivars of sea buckthorn.RAPD (Random amplified polymorphic DNA)-markkerien avulla kuvailtiin osaa tyrnin geenipankista, joka oli koottu jalostustarkoituksiin. Molekyylimarkkereita monistettiin 55 näytteestä, jotka edustivat viittä tyrnin (Hippophae rhamnoides L.) alalajia ja eri alalajien välisiä hybridejä. Kuudenkymmenenkolmen markkerin avulla laskettiin Dicen samankaltaisuus-kerroinmatriisi (Dice's similarity coefficient matrix) yksittäisten RAPD profiilien parittaisista vertailuista. Matriisiin perustuvien analyysien (UPGMA- and principal co-ordinate analyses) avulla kasvit jakautuivat ryhmiin, jotka vastaavat niiden taksonomistaluokkaa ja maantieteellistä alkuperää. AMOVA-analyysi (analysis of molecular variance) todettiin käyttökelpoiseksi menetelmäksi arvioitaessa näytteiden taksonomisten ja maantieteellisten ryhmien välisiä ja sisäisiä geneettisen muuntelun osatekijöitä. Vaikka molemmista aineiston ryhmittelyvaihtoehdoista (taksonominen ja maantieteellinen alkuperä) paljastui ryhmien välistä muuntelua, pääosa molekyylivarianssista (arviolta 75 %) luettiin yhä ryhmien sisäisen muuntelun aiheuttamaksi. Yhteenvetona toteamme, että RAPD analyysi on käyttökelpoinen menetelmä tyrninäytteiden taksonomisen ja maantieteellisen alkuperän selvittämiseen

Assessment of genetic diversity using RAPD analysis in a germplasm collection of sea buckthorn

Random amplified polymorphic DNA (RAPD) markers were used to characterize a part of a sea buckthorn gene bank collected for plant breeding purposes. Molecular markers were generated in 55 cultivars and accessions, representing five subspecies of Hippophae rhamnoides L. and intraspecific hybrids between different subspecies. Sixty-three markers were used to generate a Dice's similarity coefficient matrix of pairwise comparisons between individual RAPD profiles. Cluster (UPGMA) and principal co-ordinate analyses, based on this matrix, revealed clustering of plants into groups which generally correspond to their taxonomic classification or geographic origin. The analysis of molecular variance (AMOVA) was found useful for estimating components of genetic variation between and within taxonomic and geographic groups of accessions and cultivars. Whereas both alternatives for grouping the material (taxonomic or geographic origin) resulted in significant between-group variation, the major part of molecular variance (approximately 75%) was still attributed to variation within groups. We conclude that the RAPD analysis is useful for clarification of taxonomic and geographic origin of accessions and cultivars of sea buckthorn

Phylogenetic relationships among New Caledonian Sapotaceae (Ericales): molecular evidence for generic polyphyly and repeated dispersal

The phylogeny of a representative group of genera and species from the Sapotaceae tribe Chrysophylleae, mainly from Australia and New Caledonia, was studied by jackknife analyses of sequences of nuclear ribosomal DNA. The phylogeny conflicts with current opinions on generic delimitation in Sapotaceae. Pouteria and Niemeyera, as presently circumscribed, are both shown to be nonmonophyletic. In contrast, all species currently assigned to these and other segregate genera confined to Australia, New Caledonia. or neighboring islands, form a Supported clade. Earlier classifications in which more genera are recognized may better reflect relationships among New Caledonian taxa. Hence, there is need for a revision of generic boundaries in Chrysophylleae, and particularly within the Pouteria complex, including Leptostylis, Niemeyera, Pichoniet, Pouteria pro parte (the main part of section Oligotheca), and Pycnandra. Section Oligotheca have been recognized as the separate genus Planchonella, a monophyletic group that needs to be resurrected. Three clades with strong support in our jackknife analysis have one Australian species that is sister to a relatively large group of New Caledonian endemics, suggesting Multiple dispersal events between this small and isolated tropical island and Australia. The phylogeny also suggests an interesting case of a relatively recent and rapid radiation of several lineages of Sapotaceae within New Caledonia

Disparate relatives: Life histories vary more in genera occupying intermediate environments

Species within clades are commonly assumed to share similar life history traits, but within a given region some clades show much greater variability in traits than others. Are variable clades older, allowing more time for trait diversification? Or do they occupy particular environments, providing a wider range of abiotic or biotic opportunities for the establishment and maintenance of diverse trait attributes? Does environmental opportunity increase trait variability across all species, or is it specific to species belonging to the same clade, increasing only within-clade trait variability? We studied the variability of six life-history traits (initiation of flowering, duration of flowering, plant life span, seed mass, stress tolerance, type of reproduction) within 383 angiosperm genera from Central Europe distributed along six abiotic gradients. We compared patterns of within-genus variability to those present in the entire dataset, independent of genus membership. We found that trait variability differed strongly between genera, but did not depend on their age. Trait variability was higher within genera occupying intermediate positions along regional abiotic environmental gradients, compared with patterns across the entire dataset (and unbiased by geographical sampling, family membership or species richness). Increasing trait variability within genera reflected increasing independence of traits from the abiotic environment. We conclude that intermediate abiotic environments play an important role in maintaining and possibly generating the striking diversity of life history traits present within certain clades. They may do so by relaxing the abiotic constraints on the evolution and maintenance of species traits within clades

Species pools along contemporary environmental gradients represent different levels of diversification

Aim - Within a region, different habitat types are characterized by different species and some habitat types have higher species diversities than others. Different habitat types are also characterized by different phylogenetic clades. However, it is not known whether – within a given region – some habitat types have species pools that are more phylogenetically diversified than others. We investigated whether species pools in contemporary habitat types represent different levels of diversification of angiosperms and, if so, whether these differences correlate with particular environmental factors. We tested these relationships in a region of recent geological origin possessing a comparatively young flora, and compared the result with standard analyses of species diversity. Location The Netherlands. Methods - We studied angiosperms across the full range of habitat types present in the Netherlands. We characterized levels of diversification represented in species pools within each of these habitat types with respect to (1) taxonomic diversification, i.e. the rate of increase of richness across taxonomic ranks (relative to a null expectation for a given species richness), and (2) cladogenic diversification, i.e. the average cladogenic distance of species from the root of a phylogenetic tree of the species pool within a given region. Results - Species pools of different habitat types represented different levels of taxonomic and cladogenic diversification. These differences were strongly correlated with the environmental characteristics of the habitat type. Greater levels of taxonomic diversification were represented in the species pools of relatively dry and open habitat types. Greater levels of cladogenic diversification were represented in habitats with both dry and weakly acidic soils. The relationship between environmental factors and taxonomic and cladogenic diversification (r2 = 0.88 and 0.76, respectively) was stronger than that between environmental factors and species richness (r2 = 0.34). Main conclusions - Within a region, species resulting from particularly high rates of diversification accumulated in particular habitat types. These habitat types represent specific contemporary abiotic environments and have a tighter relationship with levels of diversification than with species richness