Genetic Modification

Genetic Manipulation (selection)

Genetic modification of organisms has been occurring through human manipulation since the beginning of agriculture. Humans selectively bred crops and livestock to propagate desirable traits in a process termed artificial selection. The original grass that gave rise to domesticated corn called teosinte hardly resembles what we think of when imagining modern maize.

Maize-teosinte
Teosinte, the progenitor of maize. Corn came about due to selective breeding.

Variation: Crop domestication

Selective breeding can yield a variety of features even within the same species. Below is selection of vegetables of the species Brassica oleracea that have been developed into different varieties over the course of agricultural history.

Starr 070730-7852 Brassica oleracea var. capitata
Cabbage: Brassica oleracea var. capitata
Brocoli 02
Broccoli: Brassica oleracea var. italica
Chou-rave 01
Kohlrabi: Brassica oleracea var. gongylodes
Romanesco Brassica oleracea Richard Bartz
Romanesco: Brassica oleracea var. botrytis

Variation: Animal domestication

Collage of Nine DogsDog morphological variation
Companion animals like dogs underwent thousands of years of domestication and selection for traits that were desirable for different circumstances. A high degree of morphological diversity exists between dog breeds and their ancestral grey wolf progenitor.

Genetic Manipulation (engineered)

Artificial selection takes multiple generations over a long period of time. With the advent of recombinant DNA and biotechnology, scientists can now genetically modify organisms through introduction of foreign genes to provide desirable characteristics within one generation. This process does not require traits to naturally arise in a species.

GloFish

Zebrafish
GloFish are transgenic zebra fish (Danio rerio) expressing variants of GFP. Bottom features a wild-type fish.
GloFish® are novelty pets that have the insertion of various cnidarian fluorescent protein genes into the genome. These fish were released in the United States in 2003 and have subsequently been developed in red, orange, and blue varieties. Black tetras and tiger barbs are also now available.

GloFish Electric Green Tetra
Black tetra (Gymnocorymbus ternetzi) GloFish
BlackTetraCloseUp
Wild-type Black Tetra

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