Abstract
Efforts to sustain the earth’s biodiversity will include the establishment and manipulation of isolated rescue populations, derived either via in situ fragmentation, or under ex situ circumstances. For target species, especially those with limited propagation resources, major goals of such projects include both the optimization of population size and the preservation of genetic diversity. Such rescue populations will be founded in a variety of ways, but little is known about how the geometric patterning of founders can affect population growth and genetic diversity retention. We have developed a computer program, NEWGARDEN, to investigate this issue for plant species that vary in life history characteristics. To use NEWGARDEN, input files are created that specify the size and structure of the preserve, the positioning and genetic diversity of the founders, and life history characteristics of the species (e.g., age-specific reproduction and mortality; gene dispersal distances; rates of selfing, etc.). The program conducts matings with consequent offspring establishment such that the virtual population develops through generations as constrained by the input. Output statistics allow comparisons of population development for populations that differ in one or more input conditions. Here, with NEWGARDEN analyses modeling a triennial species, we show that rescue population project managers will often have to carefully consider the geometric placement of founders to minimize effort expended while maximizing population growth and conservation of genetic diversity, such considerations being heavily dependent on the life history characteristics of particular species.
Highlights
The current biodiversity crisis [1] involves accelerating rates of species extinction, and includes intraspecific population losses, fragmentation, isolation, and size reductions [2]
We have developed a computer program, NEWGARDEN [5], which allows users to create virtual populations that develop from matings through generations conditioned by initial input specifications regarding the nature and structure of the preserve, founder number, geometric placement, genetic diversity, and life history characteristics
If one is making a choice between planting restoration introducees in pattern B versus C, if the only concern is maintaining genetic diversity rather than rate of population growth, pattern C offers the advantage of “bet hedging” [5], whereby one population might persist if the other is attacked by a pathogen, is destroyed by fire, or is otherwise locally negatively affected
Summary
The current biodiversity crisis [1] involves accelerating rates of species extinction, and includes intraspecific population losses, fragmentation, isolation, and size reductions [2] With such population decline and attenuation of interpopulation gene flow, populations can suffer increased losses of fitness due to elevated inbreeding and reduction of evolutionary potential due to the loss of genetic variation via random genetic drift, both potentially hastening the demise of local stands [3]. If these anthropogenic trends continue, efforts to sustain species and their population diversity will increasingly include the establishment of in situ and ex situ rescue and conservation populations [4]. There is a need to develop technologies that facilitate the success of such rescue-conservation projects
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