1,721,084 research outputs found
Genetic heterogeneity, reproductive isolation and host preferences in mealy aphids of the Hyalopterus pruni complex (Homoptera, Aphidoidea).
No full textThree taxa were detected by allozyme markers within the mealy aphids of the Hyalopterus pruni complex, having different cultivated Prunus species as main primary hosts. The genetically closer H. pruni and H. amygdali A (DNei= 0.10) never share primary hosts, whereas H. amygdali A and B (DNei= 0.32) may occasionally share them, producing few F1 hybrids. The three species proved reproductively isolated in the field, with no gene exchange. Their speciation seem to have occurred long before the agricultural revolution, crop colonization representing a host range expansion rather than a host shift, as in sympatric speciatio
Interspecific hybridization as a source of new species in orchids of the genus Dactylorhiza
No full textThe Palaearctic genus Dactylorhiza includes 8 diploid,10 autotetraploid,and about 40 allopolyploid species. Most of the latter derived by multiple crosses in space and time between the diploid (2n=40) D.saccifera s.l. and either D.incarnata s.l. or D.euxina; they have 4x=80 and reproduce sexually (Allotetraploid Marsh Orchids,AMOs). AMO species are differentiated morphologically, ecologically and genetically, have distinct ranges and show different combinations of alleles from local races of their parental species. Hybridization between D.saccifera s.l. and D.incarnata s.l. also gave origin to a few allotriploid taxa, as yet undescribed, with apomictic reproduction and clonal structure. Other Dactylorhiza hybrid species originated from crosses between the diploid (2n=40) D.romana and D.sambucina. They include: 1) the apomictic allotriploid D.insularis (3x=60), which combines two genomes of D.romana and one of D.sambucina, and had a single origin in an Iberian hybrid zone; 2) the sexual allotetraploid D.cantabrica, which combines two genomes of each parental species, and had a single quite recent origin, as indicated by its very restricted range, much smaller than that of D.insularis. The ecological and evolutionary success of Dactylorhiza hybrid species is considered, with particular regard to their mode of reproduction, environmental adaptations, and competitive success
Genetic divergence between Dactylorhiza romana and D. saccifera (Orchidaceae), with description of their natural hybrid
No full textGenetic variation in Orchis papilionacea (Orchidaceae) from the Central Mediterranean region: taxonomic inferences at intraspecific level
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