Contrasting Quantitative Traits and Neutral Genetic Markers for Genetic Resource Assessment of Mesoamerican Cedrela Odorata

We compared within-population variability and degree
of population differentiation for neutral genetic markers
(RAPDS) and eight quantitative traits in Central American
populations of the endangered tree, Cedrela odorata.
Whilst population genetic diversity for neutral markers
(Shannon index) and quantitative traits (heritability,
coefficient of additive genetic variation) were uncorrelated,
both marker types revealed strong differentiation
between populations from the Atlantic coast of Costa
Rica and the rest of the species’ distribution. The degree
of interpopulation differentiation was higher for RAPD
markers (FST = 0.67 for the sampled Mesoamerican
range) than for quantitative traits (QST = 0.30). Hence,
the divergence in quantitative traits was lower than
could have been achieved by genetic drift alone, suggesting
that balancing selection for similar phenotypes in
different populations of this species. Nevertheless, a
comparison of pair-wise estimates of population differentiation in neutral genetic markers and quantitative
traits revealed a strong positive correlation (r = 0.66)
suggesting that, for C. odorata, neutral marker divergence
could be used as a surrogate for adaptive gene
divergence for conservation planning. The utility of this
finding and suggested further work are discussed.