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Publication
Genetic diversity of two evergreen oaks (Quercus suber L. and Q (ilex) rotundifolia Lam.) in Portugal using AFLP markers
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Advisor(s)
Abstract(s)
The genetic variability of cork oak (Quercus suber, L.)
in Portugal was evaluated by AFLP using five primer
combinations. Three hundred and thirteen trees from
three geographically contrasting regions exhibited a
high level of genetic variation. The genetic profile of
each individual is composed of 291 loci, randomly positioned
in the genome and consists of monomorphic and
polymorphic fragments. Similarities and dissimilarities
among the individuals were quantitatively evaluated by
numerical taxonomy. The overall sample shows a proportion
of AFLP polymorphic markers of 71%, denoting
a high level of variability. Ninety percent of the polymorphic
markers identified in cork oak genotypes are uniformly
distributed throughout the cork oak populations
of Algarve, Alentejo and Trás-os-Montes regions. The
coefficients of genetic similarity vary from 0.61 to 0.88
implying that 60% of fragments found are common. A
sample of 52 holm oak [Quercus ilex subsp. rotundifolia
(Lam.)] trees from overlapping areas was also analysed
by AFLP with the same five primer combinations. However
the codification of markers together with those
selected on cork oak profiles was feasible with only one
primer combination due to an apparent much higher
polymorphism. AFLP and numerical taxonomy analysis
enabled to differentiate the taxa and showed that the
level of similarity observed between the profiles of the
individuals from holm oak species was lower than that
observed in cork oak, implying that apparently the
degree of polymorphism is higher in Q. ilex subsp. rotundifolia
than that quantified in Q. suber.
A Bayesian approach was used to assess Q. suber total
genetic diversity (Ht = 0.2534, P < 0.001) of which 1.7%
(Fst = 0.0172, P < 0.001) was assigned to differences
among populations. Analysis of molecular variance
(AMOVA) showed that most genetic variation is comprised
within populations (96%) while 3.6% is among
populations (Φst = 0.036, P < 0.001). Differences among
populations within geographic regions account for 2.6%
(Φsc = 0.026, P < 0.001) of the total variation and only
1.3% (Φct = 0.013, P = 0.007) is attributed to variation
among regions denoting little differentiation of populations
over a range of 700 km.
Description
Keywords
AFLP Genetic diversity Genetic introgression Quercus suber (L.) Quercus ilex subsp. rotundifolia (Lam.)
Citation
Coelho, A. C.; Lima, M. B.; Neves, D.; Cravador, Alfredo. Genetic diversity of two evergreen oaks (Quercus suber L. and Q (ilex) rotundifolia Lam.) in Portugal using AFLP markers. Silvae Genetica, 55, 3, 105-118, 2006.