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Role of inbreeding depression and purging in captive breeding and…

- - - - no significant effect of fouder relatedness on population size- pop founded with siblings < founded with nob siblings
- - - - 6 population experienced a bottleneck of a single pair of individuals
      - 6 population of offspring of fish maintained in a large out-bred stock that had experienced no bottleneck
        
        serial bottleneck treatment
        
        2 population will be used
        
        split to 12 mesocosms for 12 treatments
        
        10 extict
  - - - Fishes are exposed to be more complex environment than organisms in lab studies
      - offers an opportunity to examine responses of vertebrate population under similar conditions
    - - lack of many components of natural habitats
      - provide less control and replicability than lab studies
- - - - Environmental factors that decrease fitness of deleterious recessives homozygotes
        
        Purging more efficient
      - Stressful environment
        
        Severe inbreeding deprssion
      - Purging
        
        Successful under stressful or competitive condition
        
        Some alleles may only be effective in environment where purging has occured
        
        Alleles that become fixed in one environment
        
        Deleterious effect in other environments
    - - Slow inbreeding rate result in more efficient selection against deleterious resessive.
      - Small population
        
        High rate of inbreeding.
        
        High rate of drift
        
        result in fixation of deleterious allele
      - 1st case: Purging is due to drift
        
        mating occurs between relatives based on only chances
        
        effective
        
        under narrow range condition
        
        for lethal or highly deleterious allele
        
        ineffective
        
        at very large or small population
      - 2nd case: systematic mating scheme
        or systematic inbreeding
        
        only partially recessive allele can be purged.
        
        high effective in large population unless allele is highly deleterious
    - - Factors of purging, 1) Duration of bottleneck and 2) size of bottleneck
      - Short period in inbreeding more effective in purging for remove deleterious alleles compare to long period of breeding
      - Population in the isolated and exposed to previous bottleneck have potential to become good candidates for captive breeding or restoration programmes
        
        Low purging effect and low inbreeding depression
  - - - Having low founder population size
        
        Promote high inbreeding
        
        Similar or low percentage heterozygosity allele
    - - Having over large population size in captive
        
        Reduce inbreeding
        
        High percentage of heterozygosity allele
  - - - Purging can reduce population viability through genetic drift
    - - Bottleneck might reduced the effect of inbreeding population viability but not in all cases.
        
        Eg:Gambusia affinis
        
        Eg : Gambusia holbrooki
      - Mesocosms closer to vertebrates, high reproduction capacity, median brood size.