Aplicación de la Regla de Un‐Migrante‐por‐Generación en Conservación y Gestión

  Endangered species are commonly found in several (partially) isolated populations dispersed on different fragments of a habitat, natural reserve, or zoo. A certain level of connectivity among such populations is essential for maintaining genetic variation within and between populations to allow local and global adaptation and for preventing inbreeding depression. A rule of thumb widely accepted by the conservation community is that one migrant per generation (OMPG) into a population is the appropriate level of gene flow. This rule is based on Wright's study of his island model under a long list of simplifying assumptions. I examined the robustness of the OMPG rule to the violation of each of the many assumptions, quantifying the effect with population genetics theory. I showed that, when interpreted as one effective migrant per generation, OMPG is generally valid for real populations departing from the ideal model in the discrepancies of actual ( N ) and effective (  N e   ) population sizes and actual ( m ) and effective ( m e   ) migration rates. I also addressed the issue of converting the effective number of migrants (  M e = N e m e   ) into the actual number of migrants ( M = Nm  ) of a certain age and sex. In particular, N e < N , a case common for natural populations, did not necessarily require M > M e to maintain a certain level of differentiation among populations. Rather, translating the elusive M e into the manageable M depends on the specific causes (e.g., biased sex ratio, reproductive skew) that lead to N e < N .