Conclusions and Discussion - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 338

Such analyses may indicate that certain restoration populations are more
in need of supplementation, or other management, than others. Further
analyses can then be conducted to examine the probable effect of differences
in supplementation or modification geometry on genetic diversity
maintenance post-management.
Lande (1988, 1993) and others have argued that demographic factors
(e.g., factors affecting population growth rate) rather than genetic factors
are probably the greatest risk for the loss of establishing populations.
While NEWGARDEN analyses can assist in exploring more optimal
spationumerical patterns of introduction that better promote population
growth, in the long term, and even in the short term, genetic diversity can be a
crucial contributor to the viability and evolutionary potential of populations
developing from a small number of founders, and NEWGARDEN trials
can assist in genetic diversity maintenance.
Concluding Remarks
Recent arguments have been proposed that perhaps most plant populations
develop by forms of non-Darwinian evolution rather than from adaptation
via natural selection (e.g., Lynch 2007, and references). The non-Darwinian
alterations in gene frequencies generated in newly establishing populations
founded in random spatial patterns as described in this topic are likely to
contribute to non-adaptive evolutionary processes in many cases.
Conservation and restoration of genetic diversity will take on increasing
importance in the future as habitats become more fragmented and modifi ed
through our actions. If rapid climate change persists, it will force range
changes for many species, generating a cascade of new founding events
and a decline of many previously established small populations. It may be
increasingly necessary to assist the colonization of species threatened by
such habitat pressures into highly fragmented landscapes (Hoegh-Guldberg
et al. 2008). NEWGARDEN analyses can contribute to making decisions
about improvements that certain founding strategies might bring about
in the degree to which population growth can be accelerated and genetic
diversity preserved in these and other types of species management
projects.
With increased transportation and exchange of agricultural and
other materials, invasive species are proliferating globally. Many of these
introductions begin with a series of small, isolated populations subject to a
number of forces, including the differing geometries of founding. How such
founding events might be involved in the establishment, proliferation, and
evolution of invasive species is only now coming under study (Prentis et
al. 2008). Comparative NEWGARDEN trials can be used to model patterns
of genetic diversity fl ux in invading populations.