Session 5:
Molecular tools to assess genetic diversity: Examples for temperate and tropical forests
Reiner Finkeldey
Forest Genetics and Forest Tree Breeding, Göttingen University, Germany
The development of sound strategies for the conservation of genetic resources requires an
understanding of the spatial distribution of genetic variation. The investigation of molecular
genetic markers considerably advanced our knowledge about the spatial organisation of
genetic diversity of forest tree species, but the applicability of genetic inventories in a
conservation context is hampered by at least two factors: Even though the types and numbers
of genetic markers rapidly increased during the past decades, most of the observed variation is
likely to be selectively neutral and not related to the variation in adaptive traits or traits of
economic interest, which are of prime importance for the selection and design of genetic
resources. Furthermore, most population studies have been focussed on a comparatively small
number of species which are often widespread and not endangered while the genetic resources
of many tree species facing global or regional extinction are completely unexplored.
New opportunities to investigate the genetic basis of adaptive variation arise from
technological advances resulting in an exponentially growing availability of ‘genomic
resources’. The life history traits of (common) forest trees and preliminary evidence suggest
the possibility to associate genetic variation and adaptive traits even in natural populations, but
single gene effects may be small and difficult to detect at least as long as the observation of
variation is limited to a low number of candidate genes. ‘Population genomic’ approaches
require considerable resources and hence a focus on a few model taxa which are rarely prime
targets for conservation. On the other hand, genetic diversity of endangered taxa is likely to be
irreversibly lost before preliminary investigations have been conducted in particular in tropical
forests.
Three examples illustrate that the knowledge of genetic variation patterns at ‘neutral’ markers
is useful to guide conservation activities: The distinction of hybridizing oaks (Quercus spp.)
in a species-rich forest in Rumania, an assessment of genetic diversity patterns in Hagenia
abyssinica, a valuable tree species now threatened by extinction in Ethiopia, and an
assessment of variation of a West-African multi-purpose tree species, Blighia sapida, in
natural forests and agroforestry plantations in Benin.
Conservation-oriented research is by definition an applied activity. The problems to be
addressed must not be self-imposed but should reflect urgent societal needs and contribute to
secure threatened resources. In this context, it is important to recall that changing land-use
patterns in particular in the tropics continue to be the most significant causes of declining
global biodiversity including forest genetic resources.
Finkeldey, Reiner, Göttingen University, Forest Genetics and Forest Tree Breeding,
Büsgenweg 2, 37077 Göttingen, Germany, tel. +49 551 393536, fax +49 551 398367, email:
rfinkel@gwdg.de