Migrants’ role in Conservation and Management

The One-Migrant-per-Generation Rule in Conservation and Management

L. Scott Mills, Fred W. Allendor

Biological conservation

As a man who is in to Nilgiri tahr conservation, habitat fragmentation and connectivity between populations is of great interest to me. The small isolated populations on the Western Ghats are still a source of worry. I found this 2002 paper very interesting and useful against this backdrop.

The optimal level of connectivity between populations has taken centre stage in conservation biology amidst continuing habitat fragmentation and isolation.

The common rule of thumb is that one migrant per generation into a subpopulation is sufficient to minimize the loss of polymorphism and heterozygosity within subpopulations while allowing for divergence in allele frequencies among subpopulations.

In this paper the researchers examine the conceptual and theoretical basis of the rule and consider both genetic and nongenetic factors that influence the desired level of connectivity among subpopulations. They conclude that one migrant per generation is a desirable minimum, but it may be inadequate for many natural populations.

The researchers signs off with the suggestion “a minimum of 1 and a maximum of 10 migrants per generation would be an appropriate general rule of thumb for genetic purposes, bearing in mind that factors other than genetics may further influence the ideal level of connectivity”.

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Have wonderful weekend. The next update will be on Monday or Tuesday