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BIO120 Lecture 6 (Costs of Sex (Attracting mates takes time and energy,…

- - - - Heavy potential
        
        Local population structure (proximity) enhances mating among relatives
        
        Hermaphroditic organisms
        
        Random mating in general (small populations) can also lead to inbreeding
      - Inbreeding avoidance
        
        Plants
        
        Large flowers attract pollinators
        
        Timing of male and female reproduction offset in hermaphrodites
        
        Self-recognition mechanisms to prevent pollen from self-fertilizing
        
        Animals
        
        Dispersal before mating
        
        Delayed maturation of offspring --> less likely to encounter relative when it's their turn to mate
        
        Extra pair copulation (birds pair up for reproduction with close relatives but can still reproduce with others)
        
        Kin recognition and avoidance
    - - Changed genotypic frequencies (polymorphism still exists but heterozygosity is reduced)
        
        Heterozygosity reduces by 50% per generation
        
        Homozygosity for deleterious recessive alleles results in inbreeding depression (reduced fitness)
        
        Reduced fitness characterized by reductions in viability and reproductive output --> depression favors survival of outbred offspring
    - - 2 seeds + 1 pollen = 3 genes (vs. outcrosser with 1 seed + 1 pollen) --> more likely to be represented in succeeding generation
      - Can spread via natural selection