The document discusses different types of hybridization including single cross, double cross, three-way cross, and triple cross hybrids. It provides examples of hybrid animals like mules, ligers, and wholphins. Plant hybridization is more common than animal hybridization due to differences in pollination and chromosome doubling. The document notes that hybridization can threaten extinction if a population becomes entirely hybridized, and conservationists disagree on how to manage hybrid and pure populations.