Rescue of Endangered Populations
Rescue from extinction can take three main forms.
Demographic rescue - when population size is increased by immigration sufficiently to buffer the population against stochastic fluctuations
Genetic rescue – when immigrants prevent extinction by providing additional genetic variation on which selection can act.
Evolutionary rescue – when populations harbor enough standing genetic variation can avoid extinction via adaptation without input of immigrants
Our goal is to determine the ability of demographic inputs, genetic inputs, and rapid adaptive evolution without immigration to rescue small populations in a challenging environment from extinction. We approach this by pairing a model biological system (Tribolium flour beetles) with quantitative models that extend our previous work to better understand the context of both extinction and rescue.
The research will be mentored by Ruth Hufbauer (Bioagricultural Sciences & Pest Management), Mike Antolin (Biology) and Simon Tavener (Mathematics) are recruiting for spring 2014.
We will perform experiments on Tribolium mesocosms which are especially well suited to teasing apart the factors that determine whether and how small populations can be rescued from extinction. We control the life history of T. castaneum to mimic a seasonally breeding organism with discrete generations and an adult dispersal phase. This life history is widespread among animals and plants. Populations will be maintained in 4 by 4 cm enclosures partly filled with flour, modeling an isolated habitat, at 31ºC. Using this model system, we will implement mutliple treatments, gathering complete census data on every population every generation, running the experiment for 10-15 generations. Complementary data will include variation at microsatellite loci to track introgression as well as levels of inbreeding.
We will first develop a model for the system in the form of a parametrized deterministic map and determine its stability using the SENSAI software that was developed as a result of a previous FEScUE project. The results of the experimental study will be used to estimate parameters in the model. Small population numbers may make a stochastic modeling approach more appropriate and we will develop and test a stochastic model during the second summer of research. The goal of this modeling effort is to both make and test hypothesis outside the experimental system as well as to guide future experiments.
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