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1.
Philos Trans R Soc Lond B Biol Sci ; 370(1660): 20130382, 2015 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-25487333

RESUMO

We compared DNA, pollen and macrofossil data obtained from Weichselian interstadial (age more than 40 kyr) and Holocene (maximum age 8400 cal yr BP) peat sediments from northern Europe and used them to reconstruct contemporary floristic compositions at two sites. The majority of the samples provided plant DNA sequences of good quality with success amplification rates depending on age. DNA and sequencing analysis provided five plant taxa from the older site and nine taxa from the younger site, corresponding to 7% and 15% of the total number of taxa identified by the three proxies together. At both sites, pollen analysis detected the largest (54) and DNA the lowest (10) number of taxa, but five of the DNA taxa were not detected by pollen and macrofossils. The finding of a larger overlap between DNA and pollen than between DNA and macrofossils proxies seems to go against our previous suggestion based on lacustrine sediments that DNA originates principally from plant tissues and less from pollen. At both sites, we also detected Quercus spp. DNA, but few pollen grains were found in the record, and these are normally interpreted as long-distance dispersal. We confirm that in palaeoecological investigations, sedimentary DNA analysis is less comprehensive than classical morphological analysis, but is a complementary and important tool to obtain a more complete picture of past flora.


Assuntos
DNA de Plantas/genética , Fósseis , Sedimentos Geológicos/química , Pólen/genética , Solo/química , Sequência de Bases , DNA de Plantas/classificação , DNA de Plantas/história , Finlândia , História Antiga , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Multiplex , Federação Russa , Análise de Sequência de DNA/métodos
2.
Mol Ecol ; 22(13): 3511-24, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23587049

RESUMO

Plant and animal biodiversity can be studied by obtaining DNA directly from the environment. This new approach in combination with the use of generic barcoding primers (metabarcoding) has been suggested as complementary or alternative to traditional biodiversity monitoring in ancient soil sediments. However, the extent to which metabarcoding truly reflects plant composition remains unclear, as does its power to identify species with no pollen or macrofossil evidence. Here, we compared pollen-based and metabarcoding approaches to explore the Holocene plant composition around two lakes in central Scandinavia. At one site, we also compared barcoding results with those obtained in earlier studies with species-specific primers. The pollen analyses revealed a larger number of taxa (46), of which the majority (78%) was not identified by metabarcoding. The metabarcoding identified 14 taxa (MTUs), but allowed identification to a lower taxonomical level. The combined analyses identified 52 taxa. The barcoding primers may favour amplification of certain taxa, as they did not detect taxa previously identified with species-specific primers. Taphonomy and selectiveness of the primers are likely the major factors influencing these results. We conclude that metabarcoding from lake sediments provides a complementary, but not an alternative, tool to pollen analysis for investigating past flora. In the absence of other fossil evidence, metabarcoding gives a local and important signal from the vegetation, but the resulting assemblages show limited capacity to detect all taxa, regardless of their abundance around the lake. We suggest that metabarcoding is followed by pollen analysis and the use of species-specific primers to provide the most comprehensive signal from the environment.


Assuntos
Sedimentos Geológicos/análise , Lagos/análise , Plantas/genética , Pólen/química , Biodiversidade , Clonagem Molecular , Código de Barras de DNA Taxonômico , Primers do DNA , DNA de Plantas/análise , DNA de Plantas/genética , Fósseis , Plantas/classificação , Países Escandinavos e Nórdicos , Alinhamento de Sequência , Especificidade da Espécie
3.
Science ; 335(6072): 1083-6, 2012 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-22383845

RESUMO

It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west-an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trøndelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andøya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.


Assuntos
Ecossistema , Fósseis , Camada de Gelo , Picea , Pinus , Sequência de Bases , DNA de Cloroplastos/genética , DNA Mitocondrial/genética , Europa (Continente) , Sedimentos Geológicos , Haplótipos , Dados de Sequência Molecular , Mutação , Noruega , Picea/genética , Pinus/genética , Países Escandinavos e Nórdicos , Tempo
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