13-1: Changing the Living World Biology 2

Have you ever seen a dog show? Breeds are a result of genetic variation Introduction

Human created different breeds to do different jobs SELECTIVE BREEDING: method of breeding that allows only those individual organisms with desired characteristics to produce the next generation – By choosing which breeds we want to use, we can create different breeds Selective Breeding

Human created different breeds of dogs to do different jobs Humans use selective breeding to take advantage of natural genetic variations Almost all domestic animals are produces by selective breeding – Horses, cats, farm animals, and plants Selective Breeding

HYBRIDIZATION: breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms Some plants can be created by crossing 2 different “types” of parents – For example: crossing a disease- resistant parent with a fast- growing parent gives offspring plants both traits Selective Breeding

To help maintain traits, some breeders use inbreeding INBREEDING: continued breeding of individuals with similar characteristics to maintain the desired characteristics of a line of organisms Inbreeding helps to make sure that traits for specific species are maintained – Can cause genetic defects such as: blindness, joint problems, etc… Selective Breeding

Selective breeding is near impossible without variations Breeders can increase variations by causing mutations With the right items (radiation/chemicals) breeders can produce mutants with good mutations – Some may not be found in the normal population Increasing Variation

Causing mutations has been useful with bacteria – Increases chances of producing a useful mutation Have been able to develop hundreds of useful bacteria! Some mutant bacteria can digest oil These bacteria have been used in oil spills Increasing Variation

Drugs that prevent chromosome separation during meiosis have been useful in plant breeding Sometimes produce plants that have 2x or 3x normal chromosome numbers – Called Polyploidy (extra chromosomes) Can produce bigger stronger plants than normal plants – Bananas and Citrus! Increasing Variation