Biology Reference
In-Depth Information
In an idealized panmictic population at Hardy-Weinberg equilibrium,
population size is infi nite with no selection, mutation, immigration or
emigration. Such populations should experience no changes in gene or
genotype frequencies through time. However, real populations violate
the above conditions in different ways, and NEWGARDEN examines
how changes in gene and genotype frequencies occur in populations that
grow over generations from initially low numbers of founders introduced
in different geometric patterns. Although Hardy-Weinberg modeling has
often been used from different perspectives to examine genetic variation
change in small and establishing populations, NEWGARDEN combines
those principles with the effects of spatial constraints of both establishment
and interactions with potential mates across species that differ in life
history characteristics, yielding results that often diverge somewhat from
Hardy-Weinberg predictions derived from infi nite populations lacking
such spatial or other infl uences. NEWGARDEN analyses can be used to
explore very small to small populations (usually < 50,000 individuals) and
thus are expected to differ from models based on infi nite populations. In
examples given below we demonstrate comparative NEWGARDEN trials
in which all factors are held constant except for the spatial arrangement
of founders producing populations with different population genetic
characteristics. These examples suggest that colonization models that
arrive at one population genetics solution for a given number of founders
are not complete. Could it be that some explanations forwarded to explain
empirical population genetics observations might be improved by taking
into consideration spatial effects on developing populations? These results
call for experimentation to document whether such processes can actually
occur in experimental and natural populations.
We remind any user that because the initial conditions, infl uencing
factors, assumptions, and algorithmic data manipulations used in
NEWGARDEN modeling are extremely simplifi ed, any results produced
are not meant to provide exact predictions. However, we do hope that
NEWGARDEN will contribute both to improved understanding of
evolutionary processes in colonizing populations and to more informed
decisions concerning the best ways to introduce species into communities
where they are currently absent, or improved biodiversity conservation
practices.
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