2. Molecular Genetics and the Conservation of Diversity
31
historical component of diversity, it will be important to protect each of the major
rainforest areas, with particular emphasis on those in the north. One notable feature is that the increasing population isolation towards the north applies to both dry
and mesic adapted species, so that protection of these mesotherm outliers should
extend beyond rainforests to adjacent areas of wet and dry sclerophyll habitats.
There has not yet been a formal evaluation of the correspondence between priorities
derived from the species and genetic data for SEQ. However, the general recommendations from the latter seem consistent with the presence of locally endemic
species of herpetofauna in the rainforest areas (see McGuigan et al. 1998) and the
presence of distinctive combinations of bird species in both wet and dry forests in
the mesotherm isolates to the north (Nix 1993).
5 Future Challenges
The brief review of evidence from the Wet Tropics and SEQ fauna serve to illustrate the application of key concepts - the separation of genetic diversity due to
historical isolation from that due to adaptation and the extension of the ESU approach to species assemblages - and also point the way to combining conservation
assessment of genetic diversity with other hierarchical levels; species and ecosystems. Rather than debating which of these is most important, we should seek to
consider all three in prioritising and implementing management for conservation.
Many questions remain to be answered before the strategy outlined here can be
implemented in any general sense. These include:
• To what extent can modelling of environmental conditions, both current and
historical, predict the broad geographic pattern of historical isolation among
populations within species? The correspondance between the paleoclimate
modelling of rainforest and the area history inferred from phylogeography of
Wet Tropics vertebrates and that between the current mesotherm distribution
and patterns of genetic diversity in SEQ are encouraging. However, more
sophisticated modelling and further molecular analysis arc needed before we
can use environmental data as a surrogate for this aspect of genetic diversity.
• To what extent do historically structured communities exist in other biomes,
particularly those in more topographically uniform or recently colonised areas
(e.g., papers on comparative phylogeography in Molecular Ecology 7(3), 1998)?
•
How does natural selection operate across heterogeneous environments and
what landscape and metapopulation structures are necessary to maintain this
process?
•
Does genetic diversity within populations limit the response to selection, especially in stressful or ecologically marginal environments?
Answers to these questions, as well as further refinement of a statistical framework
and algorithms for explicitly incorporating measures of genetic diversity into area
planning will enhance our efforts to conserve biological diversity in a manner that
recognises the dynamics of the evolutionary process.
31
historical component of diversity, it will be important to protect each of the major
rainforest areas, with particular emphasis on those in the north. One notable feature is that the increasing population isolation towards the north applies to both dry
and mesic adapted species, so that protection of these mesotherm outliers should
extend beyond rainforests to adjacent areas of wet and dry sclerophyll habitats.
There has not yet been a formal evaluation of the correspondence between priorities
derived from the species and genetic data for SEQ. However, the general recommendations from the latter seem consistent with the presence of locally endemic
species of herpetofauna in the rainforest areas (see McGuigan et al. 1998) and the
presence of distinctive combinations of bird species in both wet and dry forests in
the mesotherm isolates to the north (Nix 1993).
5 Future Challenges
The brief review of evidence from the Wet Tropics and SEQ fauna serve to illustrate the application of key concepts - the separation of genetic diversity due to
historical isolation from that due to adaptation and the extension of the ESU approach to species assemblages - and also point the way to combining conservation
assessment of genetic diversity with other hierarchical levels; species and ecosystems. Rather than debating which of these is most important, we should seek to
consider all three in prioritising and implementing management for conservation.
Many questions remain to be answered before the strategy outlined here can be
implemented in any general sense. These include:
• To what extent can modelling of environmental conditions, both current and
historical, predict the broad geographic pattern of historical isolation among
populations within species? The correspondance between the paleoclimate
modelling of rainforest and the area history inferred from phylogeography of
Wet Tropics vertebrates and that between the current mesotherm distribution
and patterns of genetic diversity in SEQ are encouraging. However, more
sophisticated modelling and further molecular analysis arc needed before we
can use environmental data as a surrogate for this aspect of genetic diversity.
• To what extent do historically structured communities exist in other biomes,
particularly those in more topographically uniform or recently colonised areas
(e.g., papers on comparative phylogeography in Molecular Ecology 7(3), 1998)?
•
How does natural selection operate across heterogeneous environments and
what landscape and metapopulation structures are necessary to maintain this
process?
•
Does genetic diversity within populations limit the response to selection, especially in stressful or ecologically marginal environments?
Answers to these questions, as well as further refinement of a statistical framework
and algorithms for explicitly incorporating measures of genetic diversity into area
planning will enhance our efforts to conserve biological diversity in a manner that
recognises the dynamics of the evolutionary process.