try to understand the major points of the chapter.The students are supposed to underline the difficult words or structures and raise their questions concerning any difficulties their may have in their understanding of the text,the teacher is responsible for helping them resolve the above problems. Discussion organization(ten minutes) Organize a group discussion among students to talk about Adjacent but non-overlapping distributions In individuals with a high degree of heterozygosity,many of the genes are represented by different alleles (polymorphism):the individuals are often vigorous (heterotic).After several generations of inbreeding.individuals are usually homozygous at most loci. Genotypic variation within a population depends on the breeding systems of the organisms present,founder effects,immigration,bottlenecks and natural selection.The genotypic variation in populations may produce patterns of variation called ecotypes or ecoclines,although ofien the variation appears random. Organisms can pass genes on to their offspring by different breeding systems:by outcrossing.self-fertilisation,seed apomixis.parthenogenesis and vegetative (or asexual reproduction. The degree of heterozygosity within an individual depends on the breeding systems of its parents.In individuals with a high degree of heterozygosity,many of the genes are represented by different alleles (polymorphism):the individuals are often vigorous (heterotic).After several generations of inbreeding.individuals are usually homozygous at most loci