Directional Selection Alanna, Hailey, Sam

Table of Contents What is Directional Selection? Examples The Results What is Artificial Breeding? 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 phenotype A shift in the average range of a species

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 Cons Reproductive success Adds genetic diversity Favored Species seen as greater (enhanced and advanced) Connects to beneficial mutation 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 Any Questions? 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?