Introduction - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 6

to be constructed, are some corridor geometries more effective than others
in preserving genetic variation? If restoration ecologists could predict that
certain phases of the establishment process were more sensitive in terms
of optimizing genetic variation retention, then they could concentrate their
manipulation efforts more economically on those phases.
Effects of Life History Characteristics
What makes these issues more complex is that the life history characteristics
of species are likely to infl uence the population genetics outcomes of
different patterns of introduction. For example, in evaluating the geometry
of introduction, to what degree need we also consider whether a species
is hermaphroditic or dioecious? How might varying levels of selfi ng alter
population expansion and genetic diversity under different introduction
geometry scenarios, and what steps could be taken to attenuate potential
negative effects of inbreeding? How do distance and/or pattern of gamete
or propagule dispersal interact with founder positioning geometry? The
populations of different species, or even of one species, can grow at very
different rates. Some species are monocarpic-semelparous (e.g., annuals
and many biennials reproduce once and die), while others are polycarpic-
iteroparous (e.g., perennials grow to different sizes and ages and reproduce
more than once). When does variation in the interactions of these and
other life history features, and in their interactions with the geometry of
introduction, have a substantial impact on population growth and genetic
dynamics? What do fi ndings on the relationships of introduction geometry
with various life history characteristics imply for the types of biological
information needed to optimize the preservation of genetic diversity when
introducing a particular species? If, say, inbreeding rates or mortality rates
at certain ages prove to be especially important to the retention of genetic
diversity, then management efforts can be focused on optimizing such
factors.
Measuring Genetic Diversity
The retention of genetic diversity can be assessed in different ways. Are
different measures of population genetic diversity affected by alterations
of introduction conditions in the same ways, or to the same degrees? If
not, which measures are more important in making decisions regarding
the numbers and geometric placement of introduced plants in restoration
projects, or in analyzing evolutionary processes in natural populations? Are
there tradeoffs in contrasting measures of genetic diversity that must be
considered in conservation planning? For example, must we, in choosing