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No, founder effects are basically sampling bias. You can still have people that are genetically distant reproducing (and in fact, the popularizer of this partic

No, founder effects are basically sampling bias. You can still have people that are genetically distant reproducing (and in fact, the popularizer of this particular vein of theories in Brazil, Francis Black suggested mandating exactly this to much criticism), but the overall population diversity will remain low. However, founder effects can be associated with inbreeding if it's a sufficiently small population. I'd imagine this probably wasn't a major factor for early Americans, as the effective population size (note, not actual population size!) was on the order of thousands.

s1artibartfast 6y ago
Thanks for the explanation, but I'm still not sure I follow how they are different. Does it not count as inbreeding if mating is occurring between distant relations which have low genetic differences due to low variability in the total population?
- AlotOfReading 6y ago
  Imagine that the base population has alleles A-Z, all at equal frequency. A small population splits from the base population and becomes isolated. Because they're a small sample of the whole, they only have alleles A-M. This is the founder effect. Inbreeding would be A-A pairings (which may be more likely depending on population structure, frequencies, and size), but is not necessary. In practice, there's a huge array of complications on top of all this that affect frequencies. That's the basic idea though.
  - s1artibartfast 6y ago
    Thanks for explaining it to me this way, I think it helps. My understanding from your post is that inbreeding is typically viewed as a more extreme reduction in available alleles and there is a blurry distinction. A founding or bottlenecked population have only A alleles present, but this would generally not be described as inbreeding. The implication seems to be that to be termed inbreeding, there has to be access to more diverse pairings which for whatever reasons are not occurring.
    - AlotOfReading 6y ago
      A founder effect population would still have some genetic variance left (Alleles A through M), but it would have less than the base population (A through Z). This is a shift in allele frequencies in the population as a whole due to sampling bias. Inbreeding is reproduction by two people that are closely related (i.e. have similar alleles). Since people only have one allele in our example, that only occurs when two people with the same allele (e.g. A-A) reproduce. A-B, B-C, or any other dissimilar combination would not be inbreeding because their alleles are different, i.e. the "coefficient of inbreeding" is low. Hopefully that clarifies how they're distinct.

s1artibartfast 6y ago

Thanks for the explanation, but I'm still not sure I follow how they are different. Does it not count as inbreeding if mating is occurring between distant relations which have low genetic differences due to low variability in the total population?

AlotOfReading 6y ago
Imagine that the base population has alleles A-Z, all at equal frequency. A small population splits from the base population and becomes isolated. Because they're a small sample of the whole, they only have alleles A-M. This is the founder effect. Inbreeding would be A-A pairings (which may be more likely depending on population structure, frequencies, and size), but is not necessary. In practice, there's a huge array of complications on top of all this that affect frequencies. That's the basic idea though.
- s1artibartfast 6y ago
  Thanks for explaining it to me this way, I think it helps. My understanding from your post is that inbreeding is typically viewed as a more extreme reduction in available alleles and there is a blurry distinction. A founding or bottlenecked population have only A alleles present, but this would generally not be described as inbreeding. The implication seems to be that to be termed inbreeding, there has to be access to more diverse pairings which for whatever reasons are not occurring.
  - AlotOfReading 6y ago
    A founder effect population would still have some genetic variance left (Alleles A through M), but it would have less than the base population (A through Z). This is a shift in allele frequencies in the population as a whole due to sampling bias. Inbreeding is reproduction by two people that are closely related (i.e. have similar alleles). Since people only have one allele in our example, that only occurs when two people with the same allele (e.g. A-A) reproduce. A-B, B-C, or any other dissimilar combination would not be inbreeding because their alleles are different, i.e. the "coefficient of inbreeding" is low. Hopefully that clarifies how they're distinct.