BIO120H1 Lecture Notes - Lecture 6: Mating System, Plant Reproduction, Eichhornia Crassipes
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BIO120H1 Full Course Notes
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Document Summary
Bio120 - lecture 6: sex, reproductive systems, and evolution. Cost of producing male (when asexual reproduction is available) Sexual female 50% genes to next generation compared to asexual female. Short term benefit - benefits of genetic variation in variable environment. Tangled bank hypothesis - spatially heterogeneous environments. Theory predicts it facilitates evolution of sex, no data yet. Red queen hypothesis - temporally heterogeneous environments. Bring together favourable traits, eliminate deleterious mutations. Asexual reproduction does not allow enough time. Common in plants, though few species are exclusively asexual. Long term evolutionary potential low due to lack of genetic variation. Allele frequency changes (alleles are there but just in different genotypes) Heterozygosity reduced 50% per generation with self-fertilization. Decreases at different rates depending on mating patterns, population size. Homozygosity for deleterious recessive alleles inbreeding depression. Strong inbreeding depression favours survival of outbred offspring, outcrossed mating system. Dioecy only occurs in 7% of flowering plants.
