Biology Reference
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may be initiated very early on in the development of such populations
that will be detectable even once both populations have saturated their
environments. As seen in many of the comparative trials, the intensity of
such founding geometry effects can also depend on variation in life history
characteristics. Increasing or decreasing trends in diversity maintenance,
and even reversal of trends, can likely occur along intraspecifi c gradients
of change in some of the life history characteristics that can be used in
NEWGARDEN modeling.
Differences in the spationumeric arrangement of the same number
of founders in different populations are often driven by “random” forces
(e.g., differences in the spatial distribution of available “safe sites” for
establishment, wind direction or the water availability at safe sites at a
particular time of offspring or pollen dispersal). The consequent patterns
of population and genetic diversity retention dynamics are not caused by
natural selection, but rather stem from forms of neutral non-Darwinian
evolutionary forces. To our knowledge, the ability to explore spationumeric
variation of founding as a non-Darwinian evolutionary force on population
growth and genetic diversity dynamics in establishing isolated plant
populations has not been previously available in a program similar to
NEWGARDEN.
Discussion: NEWGARDEN, Evolutionary Theory and
Conservation Practices
When conservation restorationists or evolutionary biologists grapple with
the evolutionary processes occurring in newly founded, small, isolated
populations, they have available a beautiful array of modeling approaches.
Most of these models are elegant and often reduce to a greater simplicity
the ways in which population genetic diversity can be affected by various
evolutionary pressures. However, in their elegance, most such models are
rather simplistic, modeling the interactive behavior of only a few of those
pressures (e.g., loss of heterozygosity or unique alleles with decreasing
Ne; effects of several kinds of selection pressure; effects of different levels
of inbreeding). Our approach is much more complex in that numerous
factors can interact at once, and rather than reductive modeling via a few
equations, we try to recreate the directions in which populations develop
when numerous factors interact in a wide variety of ways. Although we
are painfully aware that the NEWGARDEN program does not in any way
cover all the population phenomena that exist, we hope the examples
given in this topic demonstrate that such incomplete approaches can reveal
complex interactions of many of the evolutionary forces at work in novel
ways. Further, while more reductive modeling clarifi es the interaction of
particular conditions, it often does not give a clear sense of the variance
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