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Role of inbreeding depression and purging in captive breeding and…

- - - - Highly deleterious alleles are successfully purged then the fitness of inbreeding population is expected to recover after initial decline. (Complete purging)
      - Highly deleterious alleles are successfully purged but slightly deleterious alleles become fixed through drift. (Partial purging)
      - Inefficient purging is expected where inbreeding depression was due to overdominance or many slightly deleterious alleles. (No purging)
- - - - High inbreeding rates which in small populations
        
        Experience high rates of genetic drift which interfere with selective changes in allele frequencies
        
        Only highly deleterious or lethal recessives are likely to be purged
      - Slow inbreeding rates which in large populations
        
        It will purge genetic load of deleterious recessive alleles more efficiently than rapid inbreeding
        
        Resulted an efficient selection toward deleterious recessives alleles
        
        Allow populations to retain environmental responsiveness than more intense inbreeding
    - - Reduced population size which cause genetic drift to occur
      - Mating between relatives occur based on chance alone
    - - Purging by drift is effective under narrow range of conditions compare to a systematic matching scheme
      - Purging under systematic inbreeding in more effective in large populations compare to the small ones. In contrast, purging is possible in which the alleles were highly deleterious.
  - - - Short bottlenecks is more common in captive breeding and reintroduction programmes than prolonged periods of small population sizes, N.
      - Brief (only few generations) bottlenecks provide potential opportunity for purging
      - Short inbreeding periods is sufficient to purge highly deleterious recessives while minimize fixation
        
        Populations that experienced bottlenecks in the past will exhibit reduced inbreeding depression which is less sensitive to future inbreeding
        
        Small and isolated population with significance inbreeding levels suggested that little purging occurred
        
        Fitness of a populations declined with additional inbreeding which had a possibility that genetic load remained after purging occurred due to bottlenecks effects. The occurrence is not subjected to additional purging in subsequent generations.
- - - - Bottlenecks might reduce effects of inbreeding on population vibility
      - Reasonable means to examine effects of purging in vertebrates is not clear due to large brood sizes (may increase viability of population when purging)
    - - To study the influence of purging to population to population viability of fish
      - Using method to explain how purging effect the growth and population viability