Integrate genetic and population processes

Ecology of Infectious Diseases

Collaborative Research: Field and Modeling Studies in Support of
Understanding Disease Resistance in Estuarine Populations and Response to Climate Change

The genetic structure of marine populations might play an import role in its response to disease. Especially important would be the genes that contain alleles associated with some specific phenotypic traits, such as reproduction or disease resistance. A number of factors, including mutation, migration, genetic drift and natural selection, can alter the frequency of alleles in a population.

We used a genetics model combined with an oyster population model to investigate the role of immigrants into an oyster population, with particular interest in migrants that contain a benefit to the population, such as disease resistance alleles.

The individual-based model simulates the genetic structure of an oyster population. It is run for 100 generations (100 years) with new immigrants being added after 50 years. Increased fitness is modeled as increased longevity.

The effect of introducing immigrants depends on whether they are larvae (=natural dispersal) or adults (=transplants), on the fraction of the receiving population that they represent, and on whether their immigration is continuous or episodic.

Preliminary results indicate that for continuous immigration, even without any selective benefit, a new allele can become dominant with an immigration rate as low as 0.1% of the receiving population. An allele introduced by episodic immigration can persist, but at a much lower frequency than an allele continuously added. For both continuous and episodic immigration, larvae with beneficial alleles are more likely to establish dominant alleles than are transplanted adults with the same beneficial alleles.

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