Section 15.1 Notes 2015

Revised on 1/28/15

Basic Vocab

Species – a group of organisms that can breed together and produce fertile offspring

Population – all of the individuals of a species that live in a certain area, at a certain time

Gene Pool – all of the genes, including all of the different alleles for each gene, that are present in a population

Selective Breeding

Selective breeding (also called artificial selection) is a way in which humans manipulate the gene pools of populations

Selective breeding – when humans select which organisms will reproduce/pass their genes to the next generation

Selective Breeding

• Human uses of selective breeding -making new varieties of cultivated plants -domestication of animals

Examples of Selective Breeding• Modern day corn is descended from a grass

called teosinte*Taken from http://evolution.berkeley.edu/evolibrary/news/070201_corn

Examples of Selective Breeding

• Dog Breeds – all breeds of dogs are descended from wolf-like ancestor *taken from http://visual.merriam-webster.com/animal-kingdom/carnivorous-mammals/dog-

breeds_1.php

Selective Breeding

• Hybridization -crossing dissimilar individuals to bring together the best of both organisms -the offspring are often hardier than the parents -many hybrids combined the disease resistance of one plant with the food- producing capacity of another

Selective Breeding

• Inbreeding -the continued breeding of individuals with similar characteristics -inbreeding is used to maintain the desirable characteristics in a line of organisms -can be a risky practice because it increases the chances that offspring will have two recessive alleles for a genetic defect

Increasing variation

• Biotechnology – the application of a technological process, invention, or method to living organisms

• Selective breeding is considered a type of biotechnology

• However, sometimes breeders want more variation than can be achieved through selective breeding

Increasing Variation

• Mutations – heritable changes in DNA• Mutations occur spontaneously in nature• Breeders can increase the mutation rate of an

organism by using radiation or chemicals• Mutations are usually harmful to the organism

but sometimes breeders can create mutations in organisms that are useful to humans

Increasing variation

• The application of radiation or chemicals to create useful mutations has been very successful with bacteria

• This technique has allowed scientists to develop hundreds of useful bacterial strains

Polyploid plants

• Polyploid – organisms that contain more than two sets of chromosomes

• Polyploidy in plants can naturally occur (it is rare in animals and if it does occur is usually fatal)

• Drugs that prevent the separation of chromosomes during meiosis are very useful in plant breeding. These drugs can produce cells that have many times the normal number of chromosomes

Polyploid Plants

• Polyploidy can quickly produce new species of plants that are larger and stronger than their diploid relatives.

• Several important crop plants such as bananas and some citrus fruits have been produced this way

Polyploid Plants