- Inbreeding depression is considered one of the major selective forces for evolution of mating systems, generally favoring mating among unrelated individuals
- the cost of inbreeding avoidance must be weighed against the potenetial costs of inbreeding avoidance and the potential nongenetic and genetic benefits derived from breeding with related individuals
- when unrelated mating partner are scarce relative to related partners, the cost of inbreeding depression may be lower than the cost of forgoing mation
- the aritcles tests whether the tapeworm Schistocephalus solidus discriminates between related and unrelated mating partners and the fitness of the offspring
- two experiments were done to test this:
- worms were given choices between related and unrelated parnters and their choices were documented
- th e eggs and offspring produced from the various matings were exanimed
- the worms maing choices were: a sibling, a unrelated worm
- and selfing (self fertilization)
- it was found that despite the evidence for strong inbreeding depression mating preference was shown for close kin (the sibling)
- evidence for inbreeding depression: eggs produced by unrelated pairs hatched at a rate 3.5 times high then those produced by siblings, eggs produced by siblings hatched at a rate of 2.3 times higher then those resulting from selfing
- 3 possible resons for the benefit of breeding kin
- indirect fitness benefits of in breeding: increase in indirect fitness is large enough to outweigh the decrease in direct fitness due to inbreeding depression
- direct fitness benefits of inbreeding: direct benefits associated with incestuous breeding outweigh the cost of inbreeding
- lower extinction risk of inbreeding populations: populations in which individuals regularly inbreed are less likely to go extinct that populations in which inbreeding is avoided
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