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Directional Selection Alanna, Hailey, Sam Table of Contents What is Directional Selection? Examples The Results What is Artificial Breeding? Examples Pros & Cons Conclusion What is it? A form of Natural Selection A phenotype of a species that is favored over the others Through natural selection the species’ generation will inherit this enhanced trait Eventually this trait will be consistently expressed in this species and onto offspring Examples of Directional Selection: Giraffes Moths Horses The Result A shift in the average range of a species phenotype Artificial Breeding Directional Selection commonly used with Artificial Breeding Humans are the directional breeders Used to produce more breeds and genetic variation in plants and animals Allows for domestication Species has a higher chance of being selected Proves that variety in species nowadays traces back to ancestral relatives Example of Artificial Breeding Ex. wolves vs. dogs: Dogs are referred to as being direct descendants of wolves, and therefore considered a subspecies. Pros Reproductive success Adds genetic diversity Favored Species seen as greater (enhanced and advanced) • Connects to beneficial mutation • • • • Cons • Traits or alleles in species become eliminated • Loss of biodiversity • No guarantee that all crossbreeding attempts will work • Population vulnerable to disease • Limited to genetic variability • Produce heritable changes Conclusion If Directional Selection continues, a species won’t have genetic variation Characteristics from the favored P-generation will carry on to the F1 Generation (their offspring) and the F2 Generation (their offspring) until the entire species has the same trait Any Questions?
